James Hansen: Difference between revisions - Wikipedia
Article Images
Line 1:
{{Short description|American physicist (born 1941)}}
{{otherpersons}}
{{Other people|James Hansen}}
{{Infobox Scientist
{{Lead too short|date=April 2021}}
|box_width =
{{Use mdy dates|date=February 2020}}
|name = James E. Hansen
{{Infobox scientist
|image = James_E_Hansen.jpg
| name = James Hansen
|image_size =
| image = James Hansen profile (cropped).jpg
|caption = Hansen at the Our Opportunity student summit
| caption = Hansen in 2005
|organised by Energy Crossroads in Denmark, March 2009 (www.our-opportunity.com).
| image_size =
|birth_date = {{birth date and age|1941|03|29}}
| birth_name = James Edward Hansen
|birth_place = [[Denison, Iowa|Denison]], [[Iowa]]
| birth_date = {{birth date and age|1941|03|29}}
|death_date =
| birth_place = [[Denison, Iowa]], U.S.
|death_place =
| death_date =
|residence =
| death_place =
|citizenship =
| fields = [[Atmospheric physics]]
|nationality =
| workplaces = Currently [[Columbia University]];<br />NASA Goddard Institute for Space Studies 1967–2013
|ethnicity =
| alma_mater = [[University of Iowa]]
|fields = Atmospheric Physics
| thesis_title = The atmosphere of Venus : a dust insulation model
|workplaces = The [[NASA]] [[Goddard Institute for Space Studies]]
| thesis_url = http://www.worldcat.org/oclc/32152921
|alma_mater = [[University of Iowa]]
| thesis_year = 1967
|doctoral_advisor =
| doctoral_advisor = [[Satoshi Matsushima]]
|academic_advisors =
| doctoral_students =
| known_for = {{Plainlist|
|notable_students =
* [[Radiative transfer]]<ref>{{Cite journal | doi = 10.1029/96JD03436| title = Radiative forcing and climate response| journal = Journal of Geophysical Research| volume = 102| issue = D6| page = 6831| year = 1997| last1 = Hansen | first1 = J.| last2 = Sato | first2 = M.| last3 = Ruedy | first3 = R. | bibcode=1997JGR...102.6831H| doi-access = }}</ref>
|known_for = [[Radiative transfer]], [[Planetary atmospheres]], <br>[[Climate models]]
* [[Atmosphere|Planetary atmospheres]]<ref>{{Cite journal | doi = 10.1007/BF00168069| title = Light scattering in planetary atmospheres| journal = Space Science Reviews| volume = 16| issue = 4| pages = 527–610| year = 1974| last1 = Hansen | first1 = J. E. | last2 = Travis | first2 = L. D. | bibcode=1974SSRv...16..527H| s2cid = 122043532}}</ref>
|influences = [[James Van Allen]]
* [[Climate model]]s<ref>{{Cite journal
|influenced =
| pmid = 17842894
|awards = [[United States National Academy of Sciences]], <br>[[Carl-Gustaf Rossby Research Medal]]
|religion year = 1992
| last1 = Charlson
|signature = <!--(filename only)-->
|footnotes first1 = R. J.
| author-link=Robert Jay Charlson
| title = Climate forcing by anthropogenic aerosols
| journal = Science
| volume = 255
| issue = 5043
| pages = 423–30
| last2 = Schwartz
| first2 = S. E.
| last3 = Hales
| first3 = J. M.
| last4 = Cess
| first4 = R. D.
| last5 = Coakley Jr
| first5 = J. A.
| last6 = Hansen
| first6 = J. E.
| last7 = Hofmann
| first7 = D. J.
| doi = 10.1126/science.255.5043.423
| bibcode = 1992Sci...255..423C
| s2cid = 26740611
}}</ref>}}
| awards = {{Plainlist|
* [[Klopsteg Memorial Award]] {{small|(2011)}}
* Member of the [[National Academy of Sciences]]
* [[Carl-Gustaf Rossby Research Medal]]}}
[[BBVA Foundation Frontiers of Knowledge Award]] {{small|(2016)}}
[[Tang Prize]] {{small|(2018)}}
{{wrap}}[[Heinz Award]] in the Environment {{small|(2001)}}
| religion =
| signature = <!--(filename only)-->
| footnotes =
| website = {{URL|www.columbia.edu/~jeh1}}
}}
'''James Edward Hansen''' (born March 29, 1941) is an American [[adjunct professor]] directing the Program on Climate Science, Awareness and Solutions<ref>{{cite web|url=http://csas.ei.columbia.edu/|title=Climate Science, Awareness and Solutions Program home page|access-date=January 3, 2018}}</ref> of the [[The Earth Institute|Earth Institute]] at [[Columbia University]]. He is best known for his research in [[climatology]], his 1988 Congressional testimony on [[climate change]] that helped raise broad awareness of [[global warming]], and his advocacy of action to avoid dangerous climate change.<ref>{{Cite journal
'''James E. Hansen''' (born March 29, 1941 in [[Denison, Iowa|Denison]], [[Iowa]]) heads the [[NASA]] [[Goddard Institute for Space Studies]] in [[New York City]], a part of the [[Goddard Space Flight Center]] in [[Greenbelt, Maryland]], Earth Sciences Division. He has held this position since 1981. He is also an [[Professors in the United States#Adjunct professor|adjunct professor]] in the Department of Earth and Environmental Sciences at [[Columbia University]].
| pmid = 17741038
| year = 1989
| last1 = Kerr
| first1 = R. A.
| title = Hansen vs. The World on the Greenhouse Threat: Scientists like the attention the greenhouse effect is getting on Capitol Hill, but they shun the reputedly unscientific way their colleague James Hansen went about getting that attention
| journal = Science
| volume = 244
| issue = 4908
| pages = 1041–3
| doi = 10.1126/science.244.4908.1041
|bibcode = 1989Sci...244.1041K }}</ref><ref name=scopus>{{Scopus|id=7404334532}}</ref><ref>{{Cite journal
| last1 = Rockström | first1 = J.
| last2 = Steffen | first2 = W.
| last3 = Noone | first3 = K.
| last4 = Persson | first4 = Å.
| last5 = Chapin Fs | first5 = F. S.
| last6 = Lambin | first6 = E. F.
| last7 = Lenton | first7 = T. M.
| last8 = Scheffer | first8 = M.
| last9 = Folke | first9 = C.
| last10 = Schellnhuber
| doi = 10.1038/461472a | first10 = H. J.
| last11 = Nykvist | first11 = B. R.
| last12 = De Wit | first12 = C. A.
| last13 = Hughes | first13 = T.
| last14 = Van Der Leeuw | first14 = S.
| last15 = Rodhe | first15 = H.
| last16 = Sörlin | first16 = S.
| last17 = Snyder | first17 = P. K.
| last18 = Costanza | first18 = R.
| last19 = Svedin | first19 = U.
| last20 = Falkenmark | first20 = M.
| last21 = Karlberg | first21 = L.
| last22 = Corell | first22 = R. W.
| last23 = Fabry | first23 = V. J.
| last24 = Hansen | first24 = J.
| last25 = Walker | first25 = B.
| last26 = Liverman | first26 = D.
| last27 = Richardson | first27 = K.
| last28 = Crutzen | first28 = P.
| last29 = Foley | first29 = J. A.
| title = A safe operating space for humanity
| journal = Nature
| volume = 461
| issue = 7263
| pages = 472–475
| year = 2009
| pmid = 19779433
|bibcode = 2009Natur.461..472R | s2cid = 205049746
| doi-access = free
}}</ref> In recent years, he has become a climate [[Activism|activist]] to [[Mitigation of global warming|mitigate the effects of global warming]], on a few occasions leading to his arrest.<ref>{{cite web|url=http://www.foxnews.com/science/2013/02/13/top-nasa-climate-scientist-arrested-again-in-white-house-protest/|title=Top NASA scientist arrested (again) in White House protest|website=[[Fox News]] |date=2013-02-13|access-date=May 23, 2015}}</ref>
Hansen also proposed an alternative approach of [[global warming]], where the 0.7°C global mean temperature increase of the last 100 years can essentially be explained by the effect of [[Greenhouse gas|greenhouse gases]] other than [[carbon dioxide]] (such as [[methane]]).<ref>{{Cite journal |last1=Hansen |first1=James |last2=Sato |first2=Makiko |last3=Ruedy |first3=Reto |last4=Lacis |first4=Andrew |last5=Oinas |first5=Valdar |date=2000-08-29 |title=Global warming in the twenty-first century: An alternative scenario |journal=Proceedings of the National Academy of Sciences |language=en |volume=97 |issue=18 |pages=9875–9880 |doi=10.1073/pnas.170278997 |doi-access=free |issn=0027-8424 |pmc=27611 |pmid=10944197 |bibcode=2000PNAS...97.9875H }}</ref>
==Early life and education==
Hansen was born in [[Denison, Iowa|Denison]], [[Iowa]], to James Ivan Hansen and Gladys Ray Hansen.<ref>Charles Sherwin Shene and Donna Hansen Stene, ''The Hansen Family,'' Decorah, IA, 2009, 56-57.</ref> He was trained in physics and astronomy in the [[space science]] program of [[James Van Allen]] at the [[University of Iowa]]. He obtained a [[Bachelor of Arts|B.A.]] in physics and mathematics with highest distinction in 1963, an [[Master of Science|M.S.]] in astronomy in 1965 and a [[Doctor of Philosophy|Ph.D.]] in physics in 1967, all three degrees from the University of Iowa. He participated in the NASA graduate traineeship from 1962 to 1966 and, at the same time, between 1965 and 1966, he was a visiting student at the Institute of Astrophysics at [[Kyoto University]] and in the department of astronomy at the [[University of Tokyo]]. He then began work at the [[Goddard Institute for Space Studies]] in 1967.<ref name="Tracker">{{cite web |url=http://earthobservatory.nasa.gov/Features/GISSTemperature/ |title=Earth's Temperature Tracker
| author=David Herring
| date=November 5, 2007
| publisher=NASA
| work=Earth Observatory
| access-date=March 19, 2010}}</ref>
==Career==
After [[graduate school]], Hansen continued his work with [[Atmospheric radiative transfer codes|radiative transfer models]], attempting to understand the [[Atmosphere of Venus|Venusian atmosphere]]. He later applied and refined these models to understand the [[Earth's atmosphere]], and in particular, the effects that [[aerosols]] and [[trace gases]] have on Earth's climate. His development and use of [[global climate model]]s has contributed to the further understanding of the [[Earth's climate]]. In 2009, his first book, ''[[Storms of My Grandchildren]]'', was published.<ref>{{Cite journal | last = Kloor | first = Keith | title = The eye of the storm | journal = Nature Reports Climate Change | volume = 1 | issue = 912 | pages = 139–140 | date = November 26, 2009 | doi = 10.1038/climate.2009.124 | doi-access = free }}</ref> In 2012, he presented the [[TED Talk]] "Why I must speak out about climate change".<ref>{{cite web|url=http://www.ted.com/talks/james_hansen_why_i_must_speak_out_about_climate_change|title=Why I must speak out about climate change|date=March 7, 2012 }}</ref>
From 1981 to 2013, he was the director of the [[NASA]] Goddard Institute for Space Studies in [[New York City]], a part of the [[Goddard Space Flight Center]].
After graduate school, Hansen continued his work with [[Atmospheric radiative transfer codes|radiative transfer models]] and attempting to understand the [[Atmosphere of Venus|Venusian atmosphere]]. This naturally led to the same computer codes being used to understand the [[Earth's atmosphere]]. He used these codes to study the effects that aerosols and trace gases have on the climate. Hansen has also contributed to the further understanding of the Earth's climate through the development and use of [[global climate model]]s.
{{As of|2014}}, Hansen directs the Program on Climate Science, Awareness and Solutions at Columbia University's Earth Institute.<ref>{{cite web|url=https://www.science.org/content/article/hansens-climate-science-and-advocacy-project-under-way|title=Hansen's Climate Science and Advocacy Project Under Way|date=February 26, 2014}}</ref> The program is working to continue to "connect the dots" from advancing basic climate science to promoting public awareness to advocating policy actions.
Hansen is best known for his research in the field of [[climatology]], his testimony on [[climate change]] to congressional committees in 1988 that helped raise broad awareness of [[global warming]], and his advocacy of action to limit the impacts of climate change.
Hansen is representing his granddaughter as well as "future generations" as plaintiffs in the ''[[Juliana v. United States]]'' lawsuit, which is suing the United States government and some of its executive branch's positions for not protecting a stable climate system.
==Education==
Hansen was trained in physics and astronomy in the [[space science]] program of Dr. [[James Van Allen]] at the [[University of Iowa]]. He obtained a B.A. in Physics and Mathematics with highest distinction in 1963, an M.S. in Astronomy in 1965 and a Ph.D. in Physics, in 1967, all three degrees from the University of Iowa. He participated in the NASA graduate traineeship from 1962 to 1966 and, at the same time, between 1965 and 1966, he was a visiting student at the Institute of Astrophysics at the [[University of Kyoto]] and in the Department of Astronomy at the [[University of Tokyo]].
==Research and publications==
As a college student at the [[University of Iowa]], Hansen was attracted to science and the research done by James Van Allen's [[space science]] program in the physics and astronomy department. A decade later, hehis focus shifted to planetary research that involved trying to understand the climate change on earth that will result from [[Human impact on the environment|anthropogenic]] changes of the atmospheric composition.
Hansen has stated that one of his research interests is radiative transfer in planetary atmospheres, especially the interpretation of [[remote sensing]] of the Earth's atmosphere and surface from satellites. Because of the ability of satellites to monitor the entire globe, they may be one of the most effective ways to monitor and study global change. His other interests include the development of [[global circulation model]]s to help understand the observed climate trends, and diagnosing human impacts on climate.<ref name="hansenbio">{{cite web|url=http://www.giss.nasa.gov/staff/jhansen.html |title=Dr. James E. Hansen |publisher=NASA |work=Personnel Directory |accessdateaccess-date=02 February 2, 2009 |archive-url=https://web.archive.org/web/20041015153937/http://www.giss.nasa.gov/staff/jhansen.html |archive-date=October 15, 2004 }}</ref>
===AtmosphereStudies of Venus===
[[ImageFile:Venus-real color.jpg|right|thumb|Venus is surrounded by a [[Atmosphere of Venus|thick atmosphere]] composed mainly of carbon dioxide and nitrogen, and its clouds are sulfuric acid. The thickness of the atmosphere initially made it difficult to determine why the surface was so hot.]]
In the late 1960s and early 1970s, following his Ph.D. dissertation, Hansen published several papers on the planet [[Venus]] following his Ph.D. dissertation. Venus has a high [[brightness temperature]] in the radio frequencies compared to the infrared. HansenHe proposed that the hot surface was the result of aerosols trapping the internal energy of the planet.<ref name="dustmodel1967">{{cite journal |authordoi=Hansen,10.1086/149410 |last1=Hansen|first1=J.E., and |first2=S. |last2=Matsushima |date=1967 |title=The atmosphere and surface temperature of Venus: A dust insulation model |journal=[[Astrophys. J.]] |volume=150 |pages=1139-11571139–1157 |url=http://pubs.giss.nasa.gov/docs/1967/1967_Hansen_Matsushima.pdf |archive-url=https://web.archive.org/web/20111020165110/http://pubs.giss.nasa.gov/docs/1967/1967_Hansen_Matsushima.pdf |archive-date=2011-10-20 |bibcode=1967ApJ...150.1139H }}</ref> More recent studies have suggested that several billion years ago, [[Atmosphere of Venus|Venus's atmosphere]] was much more like Earth's than it is now, and that there were probably substantial quantities of liquid water on the surface, but a [[runaway greenhouse effect]] was caused by the evaporation of that original water, which generated a critical level of [[greenhouse gas]]es in its atmosphere.<ref name="kasting-greenhouse">{{cite journal | title = Runaway and moist greenhouse atmospheres and the evolution of earth and Venus | authorlast1 = Kasting |first1=J.F. | journal = [[Icarus (journal)|Icarus]] | volume = 74 | issue = 3 | pages = 472–494 | yeardate = 1988 | doi = 10.1016/0019-1035(88)90116-9 | pmid=11538226 | bibcode=1988Icar...74..472K| url = https://zenodo.org/record/1253896 | type = Submitted manuscript }}</ref>
Hansen continued his study of Venus by looking at the composition of its [[clouds]]. He looked at the near-infrared reflectivity of ice clouds, compared them to observations of Venus, and found that they qualitatively agreed.<ref name="venus1968">{{cite journal |authorlast1=Hansen, |first1=J.E., and H. |last2=Cheyney |datefirst2=1968H. |title=Near infrared reflectivity of Venus and ice clouds |journal=[[J. Atmos. Sci.]] |volume=25 |issue=4 |pages=629-633629–633 |doi=10.1175/1520-0469(1968)025<0629:NIROVA>2.0.CO;2 |url=http://pubs.giss.nasa.gov/docs/1968/1968_Hansen_Cheyney.pdf |archive-url=https://web.archive.org/web/20111020171901/http://pubs.giss.nasa.gov/docs/1968/1968_Hansen_Cheyney.pdf |archive-date=2011-10-20 |bibcode=1968JAtS...25..629H |year=1968 |hdl=2060/19680027730 |s2cid=123127374 |hdl-access=free }}</ref> He also was able to use a [[Atmospheric radiative transfer codes|radiative transfer model]] to establish an upper limit to the size of the ice particles if the clouds were actually made of ice.<ref name="venusclouds1968">{{cite journal |authordoi=Hansen,10.1029/JB073i018p06136 |last1=Hansen|first1=J.E., and |first2=H. |last2=Cheyney |date=1968 |title=Comments on the paper by D.G. Rea and B.T. O'Leary, "On the composition of the Venus clouds" |journal=[[J. Geophys. Res.]] | volume=73 |pagesissue=6136-613718 }}</ref> Evidence published in the early 1980s showed that the clouds consist mainly of [[sulfur dioxide]] and [[sulfuric acid]] droplets.<ref name="venus-clouds">{{cite journal| title pages=6136–6137 Chemical composition of the atmosphere of Venus| author bibcode= Krasnopolsky V1968JGR.A., Parshev V.A.73.6136H| journal hdl= Nature2060/19680013001| volume hdl-access= 292| issue =| pages = 610–613| year = 1981 | doi = 10.1038/292610a0free }}</ref>
By 1974, the composition of Venus' clouds had not yet been determined, with many scientists proposing a wide variety of compounds, including liquid water and aqueous solutions of ferrous chloride. Hansen and Hovenier used the polarization of sunlight reflected from the planet to establish that the clouds wherewere spherical, and had a [[refractive index]] and [[cloud drop effective radius]] which eliminated all of the proposed cloud types except sulfuric acid.<ref name="polarization1974">{{cite journal |authorlast1=Hansen, |first1=J.E., and |first2=J.W. Hovenier |datelast2=1974Hovenier |title=Interpretation of the polarization of Venus |journal=J. Atmos. Sci. |volume=31 |issue=4 |pages=1137-11601137–1160 |doi=10.1175/1520-0469(1974)031<1137:IOTPOV>2.0.CO;2 |url=http://pubs.giss.nasa.gov/docs/1974/1974_Hansen_Hovenier.pdf |archive-url=https://web.archive.org/web/20111022211738/http://pubs.giss.nasa.gov/docs/1974/1974_Hansen_Hovenier.pdf |archive-date=2011-10-22 |bibcode=1974JAtS...31.1137H |year=1974 }}</ref> [[Kiyoshi Kawabata]] and Hansen expanded upon this work by looking at the variation of polarization on Venus. They found that the visible clouds are a diffuse haze rather than a thick cloud, which confirmedconfirming the same results obtained from transits across the sun.<ref name="polarization1975">{{cite journal |authorauthor1=Kawabata, K., and |author2=J.E. Hansen |date=1975 |title=Interpretation of the variation of polarization over the disk of Venus |journal=J. Atmos. Sci. |volume=32 |issue=6 |pages=1133-11391133–1139 |doi=10.1175/1520-0469(1975)032<1133:IOTVOP>2.0.CO;2 |url=http://pubs.giss.nasa.gov/docs/1975/1975_Kawabata_Hansen.pdf |archive-url=https://web.archive.org/web/20111023015046/http://pubs.giss.nasa.gov/docs/1975/1975_Kawabata_Hansen.pdf |archive-date=2011-10-23 |bibcode=1975JAtS...32.1133K |year=1975 }}</ref>
The [[Pioneer Venus project]] was launched in May 1978 and reached Venus late that same year. Hansen collaborated with [[Larry Travis]] and other colleagues in a 1979 ''[[Science (journal)|Science]]'' article that reported on the development and variability of clouds in the ultraviolet spectrum. They concludeconcluded that there are at least three different cloud materials that contribute to the images: a thin haze layer, sulfuric acid clouds, and an unknown ultraviolet absorber below the sulfuric acid cloud layer.<ref name="travis-venus-1979">{{cite journal |authorlast1=Travis, |first1=L.D., |first2=D.L. |last2=Coffeen, |first3=A.D. |last3=Del Genio, |first4=J.E. |last4=Hansen, |first5=K. |last5=Kawabata, |first6=A.A. |last6=Lacis, |first7=W.A. |last7=Lane, |first8=S.A. |last8=Limaye, |first9=W.B. |last9=Rossow, and |first10=P.H. |last10=Stone |date=1979 |title=Cloud images from the Pioneer Venus orbiter |journal=Science |volume=205 |pages=74-7674–76 |doi=10.1126/science.205.4401.74 |url=http://pubs.giss.nasa.gov/docs/1979/1979_Travis_etal_1.pdf |archive-url=https://web.archive.org/web/20111021204331/http://pubs.giss.nasa.gov/docs/1979/1979_Travis_etal_1.pdf |archive-date=2011-10-21 |pmid=17778907 |issue=4401 |bibcode=1979Sci...205...74T |s2cid=43906539 }}</ref> The linear polarization data obtained from the same mission confirmed that the low- and mid-level clouds were [[sulfuric acid]] with radius of about 1 micrometer. Above the cloud layer was a layer of submicrometre haze.<ref name="kawabata-venus-polarimetry">{{cite journal |authordoi=Kawabata,10.1029/JA085iA13p08129 |last1=Kawabata|first1=K., |first2=D.L. |last2=Coffeen, |first3=J.E. |last3=Hansen, |first4=W.A. |last4=Lane, |first5=Mko. |last5=Sato, and |first6=L.D. |last6=Travis |date=1980 |title=Cloud and hazeHaze propertiesProperties from Pioneer Venus polarimetryPolarimetry |journal=J. Geophys. Res. |volume=85 |issue=A13 |pages=81298129–8140 |bibcode=1980JGR....85.8129K}}</ref> Evidence published in the early 1980s showed that the clouds consist mainly of [[sulfur dioxide]] and [[sulfuric acid]] droplets.<ref name="venus-8140clouds">{{cite journal| title = Chemical composition of the atmosphere of Venus|last1=Krasnopolsky|first1=V.A. |last2=Parshev|first2=V.A. | journal = [[Nature (journal)|Nature]] | volume = 292| issue =5824| pages = 610–613| date = 1981 | doi = 10.1038/292610a0| bibcode=1981Natur.292..610K|s2cid=4369293 }}</ref>
===Global temperature dataanalysis===
[[ImageFile:Peoria ASOS.jpg|left|thumb|A typical [[automated airport weather station]] which records the routine hourly weather observations of temperature, weather type, wind, sky condition, and visibility. These surface stations are located around the world, and are used to derive a [[global temperature]].]]
The first [[NASA]] Goddard Institute for Space Studies (GISS) global temperature dataanalysis was published in 19871981. Hansen and his co-author analyzed the surface air temperature at meteorological stations focusing on the years from 1880 to 1985. Temperatures for stations closer together than 1000 kilometers were shown to be highly correlated, especially in the mid-latitudes, which providedproviding a way to combine the station data to providedprovide accurate long-term variations. They concludeconcluded that global mean temperatures can be determined even though meteorological stations are typically in the Northern hemisphere and confined to continental regions. Warming in the past century was found to be {{nowrap |0.5-0.7 °C}}, with warming similar in both hemispheres.<ref name="temptrends-1987">{{cite journal |authordoi=10.1029/JD092iD11p13345 |author1=Hansen, J.E., and |author2=S. Lebedeff |date=1987 |title=Global trends of measured surface air temperature |journal=J. Geophys. Res. |volume=92 |issue=D11 |pages=13345-1337213345–13372 |url=http://pubs.giss.nasa.gov/docs/1987/1987_Hansen_Lebedeff.pdf |archive-url=https://web.archive.org/web/20111020211124/http://pubs.giss.nasa.gov/docs/1987/1987_Hansen_Lebedeff.pdf |archive-date=2011-10-20 |bibcode=1987JGR....9213345H |citeseerx=10.1.1.187.9839 }}</ref> When the analysis was updated in 1988, the four warmest years on record were all in the 1980s. The two warmest years were 1981 and 1987.<ref name="temptrends-1988">{{cite journal |authorauthor1=Hansen, J., and |author2=S. Lebedeff |date=1988 |title=Global surface air temperatures: Update through 1987 |journal=Geophys. Res. Lett. |volume=15 |issue=4 |pages=323-326323–326 |doi=10.1029/88GL02067GL015i004p00323 |bibcode=1988GeoRL..15..323H|url=https://zenodo.org/record/1231388 }}</ref> During a senate meeting on June 23, 1988, Hansen reported that he was ninety-nine percent certain the earth was warmer then than at any time in the history of instrumental measurements, there was a clear cause and effect relationship with the greenhouse effect and lastly that due to global warming, the likelihood of freak weather was steadily increasing.<ref>{{Cite web|url=http://climatechange.procon.org/sourcefiles/1988_Hansen_Senate_Testimony.pdf|title=Statement of Dr. James Hansen|date=June 23, 1988|website=Climate Change|archive-url=https://web.archive.org/web/20110822055700/http://climatechange.procon.org/sourcefiles/1988_Hansen_Senate_Testimony.pdf|archive-date=August 22, 2011}}</ref>
With the [[1991 eruption of Mount Pinatubo]], 1992 saw a cooling in the global temperatures. There was speculation that this would cause the next fewcouple of years to be cooler because of the large [[serial correlation]] in the global temperatures. Bassett and Lin found the statistical odds of a new temperature record to be small.<ref name="bassettandlin">{{cite journal |authorlast1=Bassett,G.W. Jr. and|first1=G.W |first2=Z. |last2=Lin |title=Breaking global temperature records after Mt. Pinatubo |journal=Climatic Change |volume=25 |number=2 |date=1993 |doi=10.1007/BF01661205 |pages=179179–184 |url=http://tigger.uic.edu/~gib/Breaking%20Global%20Temp%20Records.pdf |issue=2 |bibcode=1993ClCh...25..179B |s2cid=154503363 |access-184date=February 12, 2009 |archive-date=February 24, 2009 |archive-url=https://web.archive.org/web/20090224211315/http://tigger.uic.edu/~gib/Breaking%20Global%20Temp%20Records.pdf }}</ref> Hansen countered by saying that having insider information shiftsshifted the odds to those thatwho know the physics of the climate system, and that whether there is a new temperature record depends upon the particular data set used.<ref name="temptrends-1993">{{cite journal |authorlast1=Hansen, |first1=J., and |first2=H. |last2=Wilson |date=1993 |title=Commentary on the significance of global temperature records |journal=Climatic Change |volume=25 |issue=2 |pages=185-191185–191 |doi=10.1007/BF01661206 |url=http://pubs.giss.nasa.gov/docs/1993/1993_Hansen_Wilson.pdf |archive-url=https://web.archive.org/web/20111021020841/http://pubs.giss.nasa.gov/docs/1993/1993_Hansen_Wilson.pdf |archive-date=2011-10-21 |bibcode=1993ClCh...25..185H |s2cid=154848782 }}</ref>
The temperature data was updated in 1999 to report that 1998 was the warmest year since the instrumental data began in 1880. They also found that the rate of temperature change was larger than at any time in instrument history, and concludeconcluded that the recent [[El NinoNiño]] was not totallysolely responsible for the large temperature anomaly in 1998. In spite of this, the United States had seen a smaller degree of warming, and a region in the eastern U.S. and the western Atlantic Ocean had actually cooled slightly.<ref name="temptrends-1999">{{cite journal |authorlast1=Hansen, |first1=J., |first2=R. |last2=Ruedy, |first3=J. |last3=Glascoe, and |first4=Mki. |last4=Sato |date=1999 |title=GISS analysis of surface temperature change |journal=J. Geophys. Res. |volume=104 |issue=D24 |pages=30997-3102230997–31022 |doi=10.1029/1999JD900835 |url=http://pubs.giss.nasa.gov/docs/1999/1999_Hansen_etal.pdf |archive-url=https://web.archive.org/web/20111021151224/http://pubs.giss.nasa.gov/docs/1999/1999_Hansen_etal.pdf |archive-date=2011-10-21 |bibcode=1999JGR...10430997H |s2cid=13720294 }}</ref>
2001 saw a major update to how the temperature was calculated. It incorporated corrections due to the following reasons: time-of-observation bias,; station history changes,; classification of rural/urban stations,station; the urban adjustment based on satellite measurements of night light intensity, and relying more on rural station than urban. Evidence was found of local urban warming in urban, suburban and small-town records.<ref name="ustemptrends-2001">{{cite journal |authorlast1=Hansen, |first1=J.E., |first2=R. |last2=Ruedy, |first3=Mki. |last3=Sato, |first4=M. |last4=Imhoff, |first5=W. |last5=Lawrence, |first6=D. |last6=Easterling, |first7=T. |last7=Peterson, and |first8=T. |last8=Karl |date=2001 |title=A closer look at United States and global surface temperature change |journal=J. Geophys. Res. |volume=106 |issue=D20 |pages=23947-2396323947–23963 |doi=10.1029/2001JD000354 |urlbibcode=http://pubs2001JGR.giss.nasa.gov/docs/2001/2001_Hansen_etal.pdf10623947H |doi-access=free }}</ref>
The anomalously high global temperature in 1998 due to [[El Niño-Southern Oscillation|El Niño]] resulted in a brief drop in subsequent years. However, a 2001 Hansen report in the journal ''Science'' states that global warming continues, and that the increasing temperatures should stimulate discussions on how to slow global warming.<ref name="hansen2002science">{{cite journal |authorlast1=Hansen, |first1=J., |first2=R. |last2=Ruedy, |first3=Mki. |last3=Sato, and |first4=K. |last4=Lo |date=2002 |title=Global warming continues |journal=Science |volume=295 |pagesissue=5553 |page=275 |doi=10.1126/science.295.5553.275c |pmid=11789536 |s2cid=29762706 |url=http://pubs.giss.nasa.gov/docs/2002/2002_Hansen_etal_1.pdf |archive-url=https://web.archive.org/web/20111021155741/http://pubs.giss.nasa.gov/docs/2002/2002_Hansen_etal_1.pdf |archive-date=2011-10-21 }}</ref> The temperature data was updated in 2006 to report that temperatures are now {{nowrap | 0.8 °C}} warmer than a century ago, and concludeconcluded that the recent global warming is a real climate change and not an artifact from the [[urban heat island effect]]. The regional variation of warming, with more warming in the higher latitudes, is further evidence of warming that is anthropogenic in origin.<ref name="hansenPNAS2006">{{cite journal |authorlast1=Hansen, |first1=J., |first2=Mki. |last2=Sato, |first3=R. |last3=Ruedy, |first4=K. |last4=Lo, |first5=D.W. |last5=Lea, and |first6=M. |last6=Medina-Elizade |date=2006 |title=Global temperature change |journal=[[Proc. Natl. Acad. Sci.]] |volume=103 |pages=14288-1429314288–14293 |doi=10.1073/pnas.0606291103 |urlpmid=http://pubs17001018 |issue=39 |pmc=1576294 |bibcode=2006PNAS.giss.nasa.gov/docs/2006/2006_Hansen_etal_1.pdf10314288H |doi-access=free }}</ref>
In 2007, [[Stephen McIntyre]] notified [[GISS]] that many of the U.S. temperature records from the [[Global Historical Climatology Network|Historical Climatology Network]] (USHCN) displayed a discontinuity around the year 2000. NASA corrected the computer code used to process the data and credited McIntyre with pointing out the flaw.<ref>{{cite web |url=http://data.giss.nasa.gov/gistemp/updates/200708.html |archive-url=https://web.archive.org/web/20071012040739/http://data.giss.nasa.gov/gistemp/updates/200708.html |archive-date=2007-10-12 |work=GISS Surface Temperature Analysis |title=August 2007 update |accessdateaccess-date=06 February 6, 2009 |date=August 2007 }}</ref> Hansen indicated that he felt that several news organizations had overreacted to this mistake.<ref name= "usufruct">{{cite web |url=http://www.columbia.edu/~jeh1/mailings/20070816_realdeal.pdf |title=The Real Deal: Usufruct & the Gorilla | author=James Hansen |date=August 2007 |accessdateaccess-date=06 February 6, 2009 |archive-url=https://web.archive.org/web/20081218204605/http://www.columbia.edu/~jeh1/mailings/20070816_realdeal.pdf |archive-date=December 18, 2008 }}</ref><ref>{{cite news|author=Marc Kaufman|title=NASA Revisions Create a Stir in The Blogosphere|publishernewspaper=The Washington Post|date=August 15, 2007|page=A6|url=httphttps://www.washingtonpost.com/wp-dyn/content/article/2007/08/14/AR2007081401677.html |accessdateaccess-date=2007-09-25}}</ref> In 2010, Hansen published a paper entitled "Global Surface Temperature Change" describing current global temperature analysis.<ref name="Globalsurfacetemperaturechange-2010">{{cite journal |author1=J. Hansen |author2=R. Ruedy |author3=M. Sato |author4=K. Lo |date=2010 |issue=4 |pages=RG4004 |title=Global Surface Temperature Change |volume=48 |journal=[[Reviews of Geophysics]] | doi=10.1029/2010RG000345 |url=http://data.giss.nasa.gov/gistemp/paper/gistemp2010_draft0803.pdf |bibcode=2010RvGeo..48.4004H|doi-access=free }}</ref>
===Black carbon studies===
[[ImageFile:Fire above Snake River.jpg|right|thumb|The incomplete combustion of biomass during the [[Yellowstone fires of 1988]] near the Snake River introduced a large quantity of black carbon particles into the atmosphere.]]
Hansen has also contributed toward the understanding of [[black carbon]] on regional climate. In recent decades, northern China has experienced increased drought, and southern China has received increased summer rain resulting in a larger number of floods. Southern China has had a decrease in temperatures while most of the world has warmed. In a paper with Menon and colleagues, thoughthrough the use of observations and climate models results, they conclude that the black carbon heats the air, increases convection and precipitation, and leads to larger surface cooling than if the aerosols were sulfates.<ref name="menon2002">{{cite journal |authorlast1=Menon, |first1=S., |first2=J.E. |last2=Hansen, |first3=L. |last3=Nazarenko, and |first4=Y. |last4=Luo |date=2002 |title=Climate effects of black carbon aerosols in China and India |journal=Science |volume=297 |pages=2250-22532250–2253 |doi=10.1126/science.1075159 |url=http://pubs.giss.nasa.gov/docs/2002/2002_Menon_etal_2.pdf |archive-url=https://web.archive.org/web/20111021153209/http://pubs.giss.nasa.gov/docs/2002/2002_Menon_etal_2.pdf |archive-date=2011-10-21 |pmid=12351786 |issue=5590 |bibcode=2002Sci...297.2250M |s2cid=38570609 }}</ref>
A year later, Hansen teamed with [[Makiko Sato]] to publish a study on black carbon using the global network of [[AERONET]] sun photometers. While the location of the AERONET instruments did not represent a global sample, they could still be used to validate global aerosol climatologies. They found that most aerosol climatologies underestimated the amount of black carbon by a factor of at least 2.<ref name="novakov2004">{{cite journal |last1=Novakov|first1=T. |first2=J.E.|last2=Hansen |date=2004 |title=Black carbon emissions in the United Kingdom during the past four decades: An empirical analysis |journal=Atmos. Environ. |volume=38 |issue=25 |pages=4155–4163 |doi=10.1016/j.atmosenv.2004.04.031 |url=http://pubs.giss.nasa.gov/docs/2004/2004_Novakov_Hansen.pdf |archive-url=https://web.archive.org/web/20111020212415/http://pubs.giss.nasa.gov/docs/2004/2004_Novakov_Hansen.pdf |archive-date=2011-10-20 |bibcode=2004AtmEn..38.4155N |s2cid=27535845 }}</ref> This corresponds to an increase in the climate forcing of around {{nowrap | 1 W/m<sup>2</sup>}}, which they hypothesize is partially offset by the cooling of non-absorbing aerosols.<ref name="sato2003">{{cite journal |authorlast1=Sato, |first1=Mki., |first2=J. |last2=Hansen, |first3=D. |last3=Koch, |first4=A. |last4=Lacis, |first5=R. |last5=Ruedy, |first6=O. |last6=Dubovik, |first7=B. |last7=Holben, |first8=M. |last8=Chin, and|first9= T. |last9=Novakov |date=2003 |title=Global atmospheric black carbon inferred from AERONET |journal=Proc. Natl. Acad. Sci. |volume=100 |pages=6319-63246319–6324 |doi=10.1073/pnas.0731897100 |urlpmid=http://pubs12746494 |issue=11 |pmc=164444 |bibcode=2003PNAS.giss.nasa100.gov/docs/2003/2003_Sato_etal.pdf6319S |doi-access=free }}</ref>
Estimations of trends in black carbon emissions show that there was a rapid increase in the 1880s after the start of the [[Industrial Revolution]], and a leveling off from 1900- to 1950 as environmental laws were enacted. China and India have recently increased their emissions of black carbon corresponding to their rapid development.<ref name="novakov2003">{{cite journal |authorlast1=Novakov, |first1=T., |first2=V. |last2=Ramanathan, |first3=J.E. |last3=Hansen, |first4=T.W. |last4=Kirchstetter,| first5=Mki. |last5=Sato, |first6=J.E. |last6=Sinton, and |first7=J.A. |last7=Satahye |date=2003 |title=Large historical changes of fossil-fuel black carbon aerosols |journal=Geophys. Res. Lett. |volume=30 |number=6 |pagespage=1324 |doi=10.1029/2002GL016345 |url=http://pubs.giss.nasa.gov/docs/2003/2003_Novakov_etal.pdf |archive-url=https://web.archive.org/web/20111020163112/http://pubs.giss.nasa.gov/docs/2003/2003_Novakov_etal.pdf |archive-date=2011-10-20 |issue=6 |bibcode=2003GeoRL..30.1324N |citeseerx=10.1.1.526.3651 |s2cid=1934875 }}</ref> The emissions from the United Kingdom were estimated using a network of stations that measured black smoke and sulfur dioxide. They report that atmospheric black carbon concentrations have been decreasing since the beginning of the record in the 1960s, and that the decline was faster than the decline in black -carbon -producing fuel use. The current estimations of black carbon emissions are likely a factor of 2 lower than actual values.<ref name="novakov2004">{{cite journal |author=Novakov, T., and J.E. Hansen |date=2004 |title=Black carbon emissions in the United Kingdom during the past four decades: An empirical analysis |journal=Atmos. Environ. |volume=38 |pages=4155-4163 |doi=10.1016/j.atmosenv.2004.04.031 |url=http://pubs.giss.nasa.gov/docs/2004/2004_Novakov_Hansen.pdf }}</ref>
A 2007 paper used the GISS climate model in an attempt to determine the origin of black carbon in the arctic. Much of the arctic aerosol comes from south Asia. Countries such as the United States and Russia have a lower contribution thatthan previously assumed. <ref name="koch-2005">{{cite journal |authorlast1=Koch, |first1= D., and |first2=J. |last2=Hansen |date=2005 |title=Distant origins of Arctic black carbon: A Goddard Institute for Space Studies ModelE experiment |journal=J. Geophys. Res. |volume=110 |issue=D4 |pages=D04204 |doi=10.1029/2004JD005296 |urlbibcode=http://pubs 2005JGRD.giss.nasa110.gov/docs/2005/2005_Koch_Hansen.pdf4204K|doi-access=free }}</ref>
===Anthropogenic impact on climate===
===Dangerous anthropogenic interference===
[[File:Miamibeachnorth.jpg|left|thumb|Hansen has warned howthat low-lying coastal areas such as Florida (seen here), East Anglia, the Netherlands, oceanic islands and Bangladesh are vulnerable to sea levels rising.<ref>{{cite journal| url=http://www.nybooks.com/articles/19131 |volume=53 |number=12 |date=13 July 13, 2006 |title=The Threat to the Planet |author=Jim Hansen |journal=The New York Review of Books |issue=12 }}</ref>]]
The [[United Nations Framework Convention on Climate Change]] is an international environmental treaty that washas aimedthe atobjective of stabilizing greenhouse gas concentrations in the atmosphere at a level that would [[Avoiding dangerous climate change|prevent dangerous anthropogenic interference with the climate system]].
In 2000, Hansen advanced an alternative view of global warming over the last 100 years, arguing that during that time frame the negative forcing via aerosols and the positive forcing via carbon dioxide ({{CO2|link=yes}}) largely balanced each other out, and that the 0.74±0.18 °C net rise in average global temperatures could mostly be explained by [[greenhouse gases]] other than carbon dioxide, such as [[methane]] and [[chlorofluorocarbons]]. However, even then he wrote "the future balance of forcings is likely to shift toward dominance of CO<sub>2</sub> over aerosols".<ref>{{cite journal|title=Global warming in the twenty-first century: An alternative scenario|first1=James|last1=Hansen|first2=Makiko|last2=Sato|first3=Reto|last3=Ruedy|first4=Andrew|last4=Lacis|first5=Valdar|last5=Oinas|date=August 29, 2000|journal=PNAS|volume=97|issue=18|pages=9875–9880|doi=10.1073/pnas.170278997|pmid=10944197|pmc=27611|bibcode=2000PNAS...97.9875H|doi-access=free}}</ref>
In 2003 Hansen wrote a paper called ''Can We Defuse the Global Warming Time Bomb'' where he argues that human-caused forces on the climate are now greater than natural ones, and that this, over a long time period, can cause large climate changes.<ref>{{cite web| author = James Hansen | year = 2003 | url= http://pubs.giss.nasa.gov/docs/2003/2003_Hansen.pdf |title = Can We Defuse the Global Warming Time Bomb |format=PDF}} </ref> He further states that a lower limit on “dangerous anthropogenic interference” is set by the stability of the Greenland and Antarctic [[ice sheets]]. His view on actions to mitigate climate change is that "halting global warming requires urgent, unprecedented international cooperation, but the needed actions are feasible and have additional benefits for human health, agriculture and the environment."
In 2003, Hansen wrote a paper called "Can We Defuse the Global Warming Time Bomb?" in which he argued that human-caused forces on the climate are now greater than natural ones, and that this, over a long time period, can cause large climate changes.<ref>{{Cite web |last=Hansen |first=James |title=Can we defuse the global warming time bomb |website=NASA Goddard Institute for Space Studies |date=2003 |url=http://pubs.giss.nasa.gov/docs/2003/2003_Hansen_ha07900q.pdf}}</ref> He further stated that a lower limit on "dangerous anthropogenic interference" was set by the stability of the Greenland and Antarctic [[ice sheet]]s. His view on actions to mitigate climate change was that "halting global warming requires urgent, unprecedented international cooperation, but the needed actions are feasible and have additional benefits for human health, agriculture and the environment."
In a 2004 presentation at the University of Iowa, Hansen announced that he was told by high-ranking government officials not to talk about how anthropogenic influence could have a dangerous effect on climate because it's not understood what dangerous means, or how human are actually affecting climate. The human-made influences of global warming are smaller than natural regional climate fluctuations. This is partially because the effects of aerosol, which act to cool the surface, and mask the warming effects of greenhouse gases. He describes this as a [[Faustian bargain]] because atmospheric aerosols have health risks, and should be reduced, but doing so will effectively increase the warming effects from {{CO2}}.<ref name="Faustianbargain2004">{{cite web |url=http://www.columbia.edu/~jeh1/2004/dai_complete_20041026.pdf |title=Dangerous Anthropogenic Interference |author=James Hansen |date=26 October 2004 |accessdate=07 February 2009 |quote=Natural regional climate fluctuations remain larger today than human-made effects such as global warming. }}</ref>
In a 2004 presentation at the University of Iowa, Hansen announced that he was told by high-ranking government officials not to talk about how anthropogenic influence could have a dangerous effect on climate because it was not understood what 'dangerous' meant, or how humans were actually affecting climate. He described this as a [[deal with the Devil|Faustian bargain]] because atmospheric aerosols had health risks, and should be reduced, but doing so would effectively increase the warming effects from {{CO2}}.<ref name="Faustianbargain2004">{{cite web |url=http://www.columbia.edu/~jeh1/2004/dai_complete_20041026.pdf |title=Dangerous Anthropogenic Interference |author=James Hansen |date=October 26, 2004 |access-date=February 7, 2009 |quote=Natural regional climate fluctuations remain larger today than human-made effects such as global warming. }}</ref>
Hansen ''et al.'' propose that the global mean temperature is a good tool to diagnose dangerous anthropogenic interference with the climate system. Two elements are particularly important when discussing dangerous anthropogenic interference: sea level rise and the extinction of species. They describe a business as usual scenario, which has greenhouse gases growing at approximately 2% per year, and an alternate scenario, in which greenhouse gases concentrations decline. Under the alternate scenario, sea levels could rise by 1 meter per century, causing problems due to the dense population in coastal areas. But this would be minor compared to the 10 meter increase in sea level under the business as normal scenario. Hansen describes the situation with species extinction similarly to sea level rise. Assuming the alternate scenario, the situation is not good, but it is much worse for business as usual.<ref name="hansenPNAS2006" />
Hansen and coauthors proposed that the global mean temperature was a good tool to diagnose dangerous anthropogenic interference with the climate system. Two elements were identified as particularly important when discussing dangerous anthropogenic interference: sea level rise and the extinction of species. They described a business-as-usual scenario, which has greenhouse gases growing at approximately 2% per year; and an alternate scenario, in which greenhouse gases concentrations decline. Under the alternate scenario, sea levels could rise by 1 meter per century, causing problems due to the dense population in coastal areas. But this would be minor compared to the 10-meter increase in sea level under the business-as-usual scenario. Hansen described the situation with species extinction similarly to that of sea level rise. Assuming the alternate scenario, the situation would not be good, but it would be much worse for business as usual.<ref name="hansenPNAS2006" />
The concept of dangerous anthropogenic interference was clarified in a 2007 paper. They find that further warming of 1C would be highly disruptive to humans. An alternative scenario would keep the warming to below this if climate sensitivity were below 3C for doubled {{CO2}}. The conclusion is that {{CO2}} levels above 450 [[ppm]] are considered dangerous, but that reduction in non-{{CO2}} greenhouse gases can provide temporary relief from drastic {{CO2}} cuts. Further, they find that arctic climate change has been forced by non-{{CO2}} constituents as much as {{CO2}}. They caution that prompt action is needed to slow {{CO2}} growth and prevent a dangerous anthropogenic interference.<ref name="hansen-interference-2007">{{cite journal |author=Hansen, J., Mki. Sato, R. Ruedy, P. Kharecha, A. Lacis, R.L. Miller, L. Nazarenko, K. Lo, G.A. Schmidt, G. Russell, I. Aleinov, S. Bauer, E. Baum, B. Cairns, V. Canuto, M. Chandler, Y. Cheng, A. Cohen, A. Del Genio, G. Faluvegi, E. Fleming, A. Friend, T. Hall, C. Jackman, J. Jonas, M. Kelley, N.Y. Kiang, D. Koch, G. Labow, J. Lerner, S. Menon, T. Novakov, V. Oinas, Ja. Perlwitz, Ju. Perlwitz, D. Rind, A. Romanou, R. Schmunk, D. Shindell, P. Stone, S. Sun, D. Streets, N. Tausnev, D. Thresher, N. Unger, M. Yao, and S. Zhang |date=2007 |title=Dangerous human-made interference with climate: A GISS modelE study |journal=Atmos. Chem. Phys. |volume=7 |pages=2287-2312|url=http://pubs.giss.nasa.gov/docs/2007/2007_Hansen_etal_1.pdf }}</ref>
The concept of dangerous anthropogenic interference was clarified in a 2007 paper, finding that further warming of 1 °C would be highly disruptive to humans. An alternate scenario would keep the warming to below this if climate sensitivity were below 3 °C for doubled {{CO2}}. The conclusion was that {{CO2}} levels above 450 [[Parts per million|ppm]] were considered dangerous, but that reduction in non-{{CO2}} greenhouse gases could provide temporary relief from drastic {{CO2}} cuts. Further findings are that arctic climate change has been forced by non-{{CO2}} constituents as much as by {{CO2}}. The 2007 paper cautioned that prompt action is needed to slow {{CO2}} growth and to prevent a dangerous anthropogenic interference.<ref name="hansen-interference-2007">{{cite journal |doi=10.5194/acp-7-2287-2007 |author1=Hansen, J. |author2=M. Sato |author3=R. Ruedy |author4=P. Kharecha |author5=A. Lacis |author6=R.L. Miller |author7=L. Nazarenko |author8=K. Lo |author9=[[Gavin Schmidt|G.A. Schmidt]] |author10=G. Russell |author11=I. Aleinov |author12=S. Bauer |author13=E. Baum |author14=B. Cairns |author15=V. Canuto |author16=M. Chandler |author17=Y. Cheng |author18=A. Cohen |author19=A. Del Genio |author20=G. Faluvegi |author21=E. Fleming |author22=A. Friend |author23=T. Hall |author24=C. Jackman |author25=J. Jonas |author26=M. Kelley |author27=N.Y. Kiang |author28=D. Koch |author29=G. Labow |author30=J. Lerner |author31=S. Menon |author32=T. Novakov |author33=V. Oinas |author34=Ja. Perlwitz |author35=Ju. Perlwitz |author36=D. Rind |author37=A. Romanou |author38=R. Schmunk |author39=D. Shindell |author40=P. Stone |author41=S. Sun |author42=D. Streets |author43=N. Tausnev |author44=D. Thresher |author45=N. Unger |author46=M. Yao |author47=S. Zhang |date=2007 |title=Dangerous human-made interference with climate: A GISS modelE study |journal=Atmos. Chem. Phys. |volume=7 |issue=9 |pages=2287–2312 |arxiv=physics/0610115 |bibcode=2007ACP.....7.2287H |s2cid=14992639 |url=http://pubs.giss.nasa.gov/docs/2007/2007_Hansen_etal_1.pdf |archive-url=https://web.archive.org/web/20111022014654/http://pubs.giss.nasa.gov/docs/2007/2007_Hansen_etal_1.pdf |archive-date=2011-10-22 |doi-access=free }}</ref>
===Climate model development and projections===
[[ImageFile:Hansen 2006 temperature comparison.jpg|right|thumb|A comparison of [[global surface temperature]] computed for three scenarios and compared with two analysis of observational data.]]
[[Vilhelm Bjerknes]] began the modern development of the general circulation model in the early twentieth20th century. The progress of numerical modeling was slow due to the slow speed of early computers and the lack of adequate observations. It wasn'twas not until the 1950s that the numerical models were getting close to being realistic.<ref>{{cite web |url=http://www.aip.org/history/climate/GCM.htm |title=General Circulation Models of Climate |work=The Discovery of Global Warming |author=Spencer Weart |publisher=[[American Institute of Physics]] |date=July 2008 |accessdateaccess-date=11 February 11, 2009 |archive-date=July 30, 2012 |archive-url=https://web.archive.org/web/20120730192534/http://www.aip.org/history/climate/GCM.htm }}</ref> Hansen's first contribution to numerical climate models came with the 1974 publication of the GISS model. He and his colleagues claimed that the model was successful in simulating the major features of sea-level pressure and 500mb heights in the North American region.<ref name="GISS-model-1974">{{cite journal |authorlast1=Somerville,|first1= R.C.J.,|first2= P.H.|last2= Stone,|first3= M. |last3=Halem,|first4= J.E. |last4=Hansen, |first5=J.S. |last5=Hogan, |first6=L.M. |last6=Druyan, |first7=G. |last7=Russell, |first8=A.A. |last8=Lacis, |first9=W.J. |last9=Quirk, and |first10=J. Tenenbaum |datelast10=1974Tenenbaum |title=The GISS model of the global atmosphere |titlevolume=J. Atmos. Sci.31 |volumeissue=311 |pages=84-11784–117 |doi=10.1175/1520-0469(1974)031<0084:TGMOTG>2.0.CO;2 |url=http://pubs.giss.nasa.gov/docs/1974/1974_Somerville_etal.pdf |archive-url=https://web.archive.org/web/20111022211028/http://pubs.giss.nasa.gov/docs/1974/1974_Somerville_etal.pdf |archive-date=2011-10-22 |issn=1520-0469 |journal=Journal of the Atmospheric Sciences |bibcode=1974JAtS...31...84S |year=1974 }}</ref>
A 1981 ''Science'' publication by Hansen and a team of scientists at Goddard concluded that carbon dioxide in the atmosphere would lead to warming sooner than previously predicted. They used a one-dimensional radiative-convective model that calculates temperature as a function of height. They reported that the results from the 1D model are similar to those of the more complex 3D models, and can simulate basic mechanisms and feedbacks.<ref name="hansen1981">{{cite journal |authorlast1=Hansen, |first1=J., |first2=D. |last2=Johnson, |first3=A. |last3=Lacis, |first4=S. |last4=Lebedeff, |first5=P. |last5=Lee, |first6=D. |last6=Rind, and |first7=G. |last7=Russell |date=1981 |title=Climate impact of increasing atmospheric carbon dioxide |journal=Science |volume=213 |pages=957-966957–966 |doi=10.1126/science.213.4511.957 |url=http://pubs.giss.nasa.gov/docs/1981/1981_Hansen_etal.pdf |archive-url=https://web.archive.org/web/20111021210222/http://pubs.giss.nasa.gov/docs/1981/1981_Hansen_etal.pdf |archive-date=2011-10-21 |pmid=17789014 |issue=4511 |bibcode=1981Sci...213..957H |s2cid=20971423 }}</ref> Hansen predicted that temperatures would rise out of the climate noise by the 1990s, much earlier than predicted by other researches. He also predicted that it would be difficult to convince politicians and the public to react.<ref>"Experts Find Possible Climatic 'Bomb'", Eleanor Randolph, Staff writer, ''[[Los Angeles Times]]'', August 9, 1981, pg B3</ref>
By the early 1980s, the computational speed of computers, along with refinements in climate models, allowed longer experiments. The models now included physics beyond the previous equations, such as convection schemes, diurnal changes, and snow -depth calculations. The advances in computational efficiency, combined with the added physics, meant the GISS model I could be run for five years. TheyIt was showedshown that global climate can be simulated reasonably well with a grid-point resolution as coarse as 1000 kilometers.<ref name="3dmodels-1983">{{cite journal |authorlast1=Hansen, |first1=J., |first2=G. |last2=Russell, |first3=D. |last3=Rind, |first4=P. |last4=Stone, |first5=A. |last5=Lacis, |first6=S. |last6=Lebedeff, |first7=R. |last7=Ruedy, and |first8=L. Travis |datelast8=1983Travis |title=Efficient three-dimensional global models for climate studies: Models I and II |journal=MMon. Weather Rev. volume=111 |pages=609-662609–662 |doi=10.1175/1520-0493(1983)111<0609:ETDGMF>2.0.CO;2 |issue=4 |url=http://pubs.giss.nasa.gov/docs/1983/1983_Hansen_etal.pdf |archive-url=https://web.archive.org/web/20111021210039/http://pubs.giss.nasa.gov/docs/1983/1983_Hansen_etal.pdf |archive-date=2011-10-21 |volume=111 |bibcode=1983MWRv..111..609H |year=1983 }}</ref>
The first climate prediction computed from a general circulation model that was published by Hansen was in 1988, the same year as his well-known Senate testimony.<ref name=nyt19880624>{{cite news |page=1 | title= Global Warming Has Begun, Expert Tells Senate| first1= Philip|last1=Shabecoff
The first climate prediction computed from a general circulation model that was published by Hansen was in 1988, the same year as his well-known Senate testimony. It used the second generation of the GISS model to estimate the change in mean surface temperature based on a variety of scenarios of future greenhouse gas emissions. Hansen concluded that global warming would be evident within the next few decades, and that it would result in temperatures at least as high as during the [[Eemian]]. He argued that, if the temperature rises {{nowrap | 0.4 °C}} above the 1950-1980 mean for a few years, it is the "smoking gun" pointing to human-caused global warming.<ref name="3dforecast-1988">{{cite journal |author=Hansen, J., I. Fung, A. Lacis, D. Rind, Lebedeff, R. Ruedy, G. Russell, and P. Stone |date=1988 |title=Global climate changes as forecast by Goddard Institute for Space Studies three-dimensional model |journal=J. Geophys. Res. |volume=93 |pages=9341-9364 |doi=10.1029/88JD00231 |url=http://pubs.giss.nasa.gov/docs/1988/1988_Hansen_etal.pdf }}</ref>
| url= https://www.nytimes.com/1988/06/24/us/global-warming-has-begun-expert-tells-senate.html| newspaper= [[New York Times]] |date= June 24, 1988
| access-date= August 1, 2012 | quote = ...Dr. James E. Hansen of the National Aeronautics and Space Administration told a Congressional committee that it was 99 percent certain that the warming trend was not a natural variation but was caused by a buildup of carbon dioxide and other artificial gases in the atmosphere.
}}</ref> The second generation of the GISS model was used to estimate the change in [[mean surface temperature]] based on a variety of scenarios of future greenhouse gas emissions. Hansen concluded that global warming would be evident within the next few decades, and that it would result in temperatures at least as high as during the [[Eemian]]. He argued that if the temperature rose {{nowrap | 0.4 °C}} above the 1950–1980 mean for a few years, it would be the "smoking gun" pointing to human-caused global warming.<ref name="3dforecast-1988">{{cite journal |last1=Hansen|first1=J.|first2=I.|last2=Fung|first3=A.|last3=Lacis|first4=D.|last4=Rind|first5=S.|last5=Lebedeff|first6=R.|last6=Ruedy|first7=G.|last7=Russell|first8=P|last8=Stone |date=1988 |title=Global climate changes as forecast by Goddard Institute for Space Studies three-dimensional model |journal=J. Geophys. Res. |volume=93 |issue=D8 |pages=9341–9364 |doi=10.1029/JD093iD08p09341 |url=http://pubs.giss.nasa.gov/docs/1988/1988_Hansen_etal.pdf |archive-url=https://web.archive.org/web/20111021105203/http://pubs.giss.nasa.gov/docs/1988/1988_Hansen_etal.pdf |archive-date=2011-10-21 |bibcode=1988JGR....93.9341H }}</ref>
[[File:James Hansen.jpg|thumb|right|Hansen giving testimony before the [[United States Congress]] in 1988]]
In 2006, Hansen and colleagues compared the observations with the projections made by Hansen in his 1988 testimony before the United States Congress. They described the intermediate scenario as the most likely, and that real-world greenhouse gas forcing has been closest to this scenario. It contained the effects of three volcanic eruptions in the fifty year projections, with one in the 1995, whereas the recent [[Mount Pinatubo]] eruption was in 1991. They found that the observed warming was similar to two of the three scenarios. The warming rates of the two most modest warming scenarios are nearly the same through the year 2000, and they were unable to provide a precise model assessment. They did note that the agreement between the observations and the intermediate scenario was accidental because the [[climate sensitivity]] used was higher than current estimates.<ref name="hansenPNAS2006" />
In 2006, Hansen and colleagues compared the observations with the projections made by Hansen in his 1988 testimony before the [[United States Congress]]. They described the intermediate scenario as the most likely, and that real-world greenhouse gas forcing had been closest to this scenario. It contained the effects of three volcanic eruptions in the fifty-year projections. They found that the observed warming was similar to two of the three scenarios. The warming rates of the two most modest warming scenarios were nearly the same through the year 2000, and they were unable to provide a precise model assessment. They noted that the agreement between the observations and the intermediate scenario was accidental because the [[climate sensitivity]] used was higher than current estimates.<ref name="hansenPNAS2006" />
A year later, heHansen joined with [[Stefan Rahmstorf|Rahmstorf]] and colleagues comparing climate projections with observations. The comparison iswas done from 1990 through January 2007 against physics-based models that are independent from the observations after 1990. They showshowed that the climate system may be responding faster than the models indicate. Rahmstorf ''etand al.''coauthors showshowed concern that [[current sea level rise|sea levels are rising]] at the high range of the IPCC projections, and that itthis iswas due to thermal expansion and not from melting of the [[Greenland ice sheet|Greenland]] or [[Antarctic ice sheets]].<ref name="rahmstorf2007">{{cite journal |authorlast1=Rahmstorf, |first1=S., |first2=A. |last2=Cazenave, |first3=J.A. |last3=Church, |first4=J.E. |last4=Hansen, |first5=R.F. |last5=Keeling, |first6=D.E. |last6=Parker, and |first7=R.C.J. |last7=Somerville |date=2007 |title=Recent climate observations compared to projections |journal=Science |volume=316 ||issue=709 |doi=10.1126/science.1136843 |url=http://pubs.giss.nasa.gov/docs/2007/2007_Rahmstorf_etal.pdf |archive-url=https://web.archive.org/web/20111022015322/http://pubs.giss.nasa.gov/docs/2007/2007_Rahmstorf_etal.pdf |archive-date=2011-10-22 |quote=Previous projections, as summarized by IPCC, have not exaggerated but may in some respects even have underestimated the change. |pmid=17272686 |page=709 |bibcode=2007Sci...316..709R |s2cid=34008905 }}</ref>
Following the launch of spacecraft capable of determining temperatures, [[Roy Spencer (scientist)|Roy Spencer]] and [[John Christy]] published the first version of their [[satellite temperature measurements]] in 1990. Contrary to climate models and surface measurements, their results showed a cooling in the [[troposphere]].<ref name="spencer and christy">{{cite journal |authorlast1=Spencer, |first1=R.W. And |first2=J.R. |last2=Christy | title=Precise Monitoring of Global Temperature Trends from Satellites | urlbibcode=http://adsabs.harvard.edu/abs/1990Sci...247.1558S | journal=[[Science (journal)|Science]] | yeardate=1990 | volume=247 | issue=4950 | pages=1558–1562 |doi=10.1126/science.247.4950.1558-1562 |pmid=17782811 | s2cid=22244815 }}</ref> InHowever, in 1998, Wentz and Schabel determined that [[orbital decay]] had an effect on the derived temperatures.<ref name="wentzand schabel">{{cite journal |journal=Nature |volume=394 |issue=6694 |pages=661-664661–664 |date=1998 | doi=10.1038/29267 |title=Effects of orbital decay on satellite-derived lower-tropospheric temperature trends |authorauthor1=Wentz, F.J. and |author2=M. Schabel |bibcode = 1998Natur.394..661W |s2cid=1345798 }}</ref> Hansen compared the corrected troposphere temperatures with the results of the published GISS model, and concluded that the model is in good agreement with the observations, noting that the satellite temperature data had been the last holdout of [[Climate change denial|global warming denialists]], and that the correction of the data would result in a change from discussing whether global warming wasis occurring to what is the rate of global warming, and what should be done about it.<ref name="science-1998">{{cite journal |authorlast1=Hansen, |first1=J.E., |first2=Mki. |last2=Sato, |first3=R. |last3=Ruedy, |first4=A. |last4=Lacis, and |first5=J. |last5=Glascoe |date=1998 |title=Global climate data and models: A reconciliation |journal=Science |volume=281 |issue=5379 |pages=930-932930–932 |doi=10.1126/science.281.5379.930 |s2cid=129403184 |url=http://pubs.giss.nasa.gov/docs/1998/1998_Hansen_etal_3.pdf |archive-url=https://web.archive.org/web/20111021083719/http://pubs.giss.nasa.gov/docs/1998/1998_Hansen_etal_3.pdf |archive-date=2011-10-21 }}</ref>
Hansen has continued the development and diagnostics of climate models. For instance, he has helped lookin atthe investigations of the decadal trends in [[tropopause]] height, which could be a useful tool for determining the human "fingerprint" on climate.<ref name="santer-2003">{{cite journal |authorlast1=Santer, |first1=B.D., |first2=R. |last2=Sausen, |first3=T.M.L. |last3=Wigley, |first4=J.S. |last4=Boyle, |first5=K. |last5=AchutaRao, |first6=C. |last6=Doutriaux, |first7=J.E. |last7=Hansen, |first8=G.A. |last8=Meehl, |first9=E. |last9=Roeckner, |first10=R. |last10=Ruedy, |first11=G. |last11=Schmidt, and |first12=K.E. |last12=Taylor |date=2003 |title=Behavior of tropopause height and atmospheric temperature in models, reanalyses, and observations: Decadal changes |journal=J. Geophys. Res. |volume=108 |number=D1 |pagespage=4002 |doi=10.1029/2002JD002258 |urlissue=http://pubsD1 |bibcode=2003JGRD.giss.nasa108.gov/docs/2003/2003_Santer_etal.pdf4002S |doi-access=free |hdl=11858/00-001M-0000-0012-01DA-8|hdl-access=free}}</ref> {{As of | 2009 | 2 |12}}, the current version of the GISS model is Model E. This version has seen improvements in many areas, including upper-level winds, cloud height, and precipitation. This model still has problems with regions of [[marine stratocumulus]] clouds.<ref name="schmidt-2006">{{cite journal |authorlast1=Schmidt, |first1=G.A., |first2=R. |last2=Ruedy, |first3=J.E. |last3=Hansen, |first4=I. |last4=Aleinov, |first5=N. |last5=Bell, |first6=M. |last6=Bauer, |first7=S. |last7=Bauer, |first8=B. |last8=Cairns, |first9=V. |last9=Canuto, |first10=Y. |last10=Cheng, |first11=A. |last11=Del Genio, |first12=G. |last12=Faluvegi, |first13=A.D. |last13=Friend, |first14=T.M. |last14=Hall, |first15=Y. |last15=Hu, |first16=M. |last16=Kelley, |first17=N.Y. |last17=Kiang, |first18=D. |last18=Koch, |first19=A.A. |last19=Lacis, |first20=J. |last20=Lerner, |first21=K.K. |last21=Lo, |first22=R.L. |last22=Miller, |first23=L. |last23=Nazarenko, |first24=V. |last24=Oinas, |first25=Ja. |last25=Perlwitz, |first26=Ju. |last26=Perlwitz, |first27=D. |last27=Rind, |first28=A. |last28=Romanou, |first29=G.L. |last29=Russell, |first30=Mki. |last30=Sato, |first31=D.T. |last31=Shindell, |first32=P.H. |last32=Stone, |first33=S. |last33=Sun, |first34=N. |last34=Tausnev, |first35=D. |last35=Thresher, and |first36=M.-S. |last36=Yao |date=2006 |title=Present day atmospheric simulations using GISS ModelE: Comparison to in-situ, satellite and reanalysis data |journal=J. Climate |volume=19 |issue=2 |pages=153-192153–192 |doi=10.1175/JCLI3612.1 |url=http://pubs.giss.nasa.gov/docs/2006/2006_Schmidt_etal_1.pdf |archive-url=https://web.archive.org/web/20111015003555/http://pubs.giss.nasa.gov/docs/2006/2006_Schmidt_etal_1.pdf |archive-date=2011-10-15 |bibcode=2006JCli...19..153S }}</ref> A later paper showed that the model's main problems are having too weak of an [[El Niño-Southern Oscillation|ENSO]]-like variability, and poor sea ice modeling, resulting in too little ice in the [[Southern Hemisphere]] and too much in the [[Northern Hemisphere]].<ref name="hansen-modele-2007">{{cite journal |authorlast1=Hansen, |first1=J., |first2=Mki. |last2=Sato, |first3=R. |last3=Ruedy, |first4=P. |last4=Kharecha, |first5=A. |last5=Lacis, |first6=R.L. |last6=Miller, |first7=L. |last7=Nazarenko, |first8=K. |last8=Lo, |first9=G.A. |last9=Schmidt, |first10=G. |last10=Russell, |first11=I. |last11=Aleinov, |first12=S. |last12=Bauer, |first13=E. |last13=Baum, |first14=B. |last14=Cairns, |first15=V. |last15=Canuto, |first16=M. |last16=Chandler, |first17=Y. |last17=Cheng, |first18=A. |last18=Cohen, |first19=A. |last19=Del Genio, |first20=G. |last20=Faluvegi, |first21=E. |last21=Fleming, |first22=A. |last22=Friend, |first23=T. |last23=Hall, |first24=C. |last24=Jackman, |first25=J. |last25=Jonas, |first26=M. |last26=Kelley, |first27=N.Y. |last27=Kiang, |first28=D. |last28=Koch, |first29=G. |last29=Labow, |first30=J. |last30=Lerner, |first31=S. |last31=Menon, |first32=T. |last32=Novakov, |first33=V. |last33=Oinas, |first34=Ja. |last34=Perlwitz, |first35=Ju. |last35=Perlwitz, |first36=D. |last36=Rind, |first37=A. |last37=Romanou, |first38=R. |last38=Schmunk, |first39=D. |last39=Shindell, |first40=P. |last40=Stone, |first41=S. |last41=Sun, |first42=D. |last42=Streets, |first43=N. |last43=Tausnev, |first44=D. |last44=Thresher, |first45=N. |last45=Unger, |first46=M. |last46=Yao, and |first47=S. |last47=Zhang |date=2007 |title=Climate simulations for 1880-20031880–2003 with GISS modelE |journal=Clim. DynamDyn. |volume=29 |issue=7–8 |pages=661-696661–696 |doi=10.1007/s00382-007-0255-8 |url=http://pubs.giss.nasa.gov/docs/2007/2007_Hansen_etal_3.pdf |archive-url=https://web.archive.org/web/20111015003434/http://pubs.giss.nasa.gov/docs/2007/2007_Hansen_etal_3.pdf |archive-date=2011-10-15 |arxiv=physics/0610109 |bibcode=2007ClDy...29..661H |hdl=10871/24402 |s2cid=73667392 }}</ref>
===Climate forcings, feedbacks, and sensitivity===
[[ImageFile:NasaHansenFig1.gif|thumb|right|Estimated [[climate forcings]] between 1850 and 2000]]
In 2000 heHansen authored a paper called ''"Global warming in the twenty-first century: an alternative scenario''" in which he presentspresented a more optimistic way of dealing with global warming, focusing on non-CO<sub>2</sub> gases and [[black carbon]] in the short run, giving more time to make reductions in [[fossil fuel emissions]].<ref>{{cite journal | last = Hansen | first = James | coauthorsdisplay-authors =''et al.''etal | yeardate = 2000 | url= http://www.giss.nasa.gov/research/features/altscenario/ |title = Global warming in the twenty-first century: An alternative scenario | journal = Proc. Natl. Acad. Sci. | volume = 97 | pages = 9875–9880 | doi = 10.1073/pnas.170278997 | pmid = 10944197 | issue = 18 | pmc = 27611 | bibcode = 2000PNAS...97.9875H | doi-access = free }} </ref> He notes that the net warming observed to date is roughly as big as that expected from non-CO<sub>2</sub> gases only. This is because CO<sub>2</sub> warming is offset by climate-cooling aerosols emitted with fossil fuel burning and because at that time non-CO<sub>2</sub> gases, taken together, were responsible for roughly 50% of the anthropogenic greenhouse gas warming.
In a 2007 paper published May 18, 2007, Hansen discussed the potential danger of "fast-feedback" effects causing [[ice sheet]] disintegration, based on [[paleoclimate]] data.<ref name= "trace" /> [[George Monbiot]] reports "The [[IPCC]] predicts that sea levels could rise by as much as 59cm{{convert|59|cm|ft}} this century.<ref>{{cite web| author = Intergovernmental Panel on Climate Change | month date= February | year = 2007 | url= http://www.ipcc.ch/SPM2feb07.pdf |title = Climate Change 2007: The Physical Science Basis -– Summary for Policymakers. Table SPM-3. |formatarchive-url=PDFhttps://web.archive.org/web/20071114144734/http://www.ipcc.ch/SPM2feb07.pdf |archive-date=2007-11-14 |author-link=Intergovernmental Panel on Climate Change }} </ref> Hansen’sHansen's paper argues that the slow melting of ice sheets the panel expects doesn’tdoesn't fit the data. The geological record suggests that ice at the poles does not melt in a gradual and linear fashion, but flips suddenly from one state to another. When temperatures increased to {{convert|2-|–|3 degrees|C|F}} above today’stoday's level 3.5 million years ago, sea levels rose not by 59 centimetrescentimeters but by {{convert|25 metres|m|ft}}. The ice responded immediately to changes in temperature."<ref>{{cite web| author = George Monbiot | date = 3 July 3, 2007 | url= http://www.monbiot.com/archives/2007/07/03/a-sudden-change-of-state/ |title = A Sudden Change of State.}} </ref>
Hansen stressesstressed the uncertainties around these predictions:. "It is difficult to predict time of collapse in such a nonlinear problem ...… An ice sheet response time of centuries seems probable, and we cannot rule out large changes on decadal time-scales once wide-scale surface melt is underway."<ref name= "trace" /> andHe concludes that "Presentpresent knowledge does not permit accurate specification of the dangerous level of human-made GHGs[greenhouse gases]. However, it is much lower than has commonly been assumed. If we have not already passed the dangerous level, the energy infrastructure in place ensures that we will pass it within several decades."<ref name= "trace">{{cite journal | last=Hansen | first = James | coauthors display-authors=''et al.''etal | year date= 2007 | url= http://pubs.giss.nasa.gov/docs/2007/2007_Hansen_etal_2.pdf |titlearchive-url=https://web.archive.org/web/20111022020035/http://pubs.giss.nasa.gov/docs/2007/2007_Hansen_etal_2.pdf |archive-date=2011-10-22 |title=Climate change and trace gases | journal = Phil. Trans. Roy. Soc. A | volume = 365 | pages = 1925–1954 | format = [[Portable Document Format|PDF]] |doi = 10.1098/rsta.2007.2052 |pmid=17513270 |issue=1856 |bibcode=2007RSPTA.365.1925H |s2cid=8785953 }}</ref>
In 2013, Hansen authored a paper called "Climate sensitivity, sea level and atmospheric carbon dioxide," in which he estimated climate sensitivity to be (3±1){{nbsp}}°C based on [[Pleistocene]] [[paleoclimate]] data. The paper also concluded that burning all fossil fuels "would make most of the planet uninhabitable by humans."<ref>{{Cite journal | doi = 10.1098/rsta.2012.0294| pmid = 24043864| pmc = 3785813| title = Climate sensitivity, sea level and atmospheric carbon dioxide| journal = Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences| volume = 371| issue = 2001| page = 20120294| year = 2013| last1 = Hansen | first1 = J.| last2 = Sato | first2 = M.| last3 = Russell | first3 = G.| last4 = Kharecha | first4 = P.|arxiv = 1211.4846 |bibcode = 2013RSPTA.37120294H }}</ref>
==Responsibility for climate change==
In 2016, a team of 19 researchers led by Hansen published a paper "Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2 °C global warming could be dangerous" describing the effect of meltwater from ice sheets on the [[Atlantic meridional overturning circulation]] (slowing it or even stopping) and [[Antarctic bottom water]] formation. This would speed up ice sheet melting and sea level rise by increasing the water temperature at hundreds of meters depth, thawing ice shelves from below. And the cool fresh meltwater on the ocean close to Greenland and Antarctica leads to larger temperature difference between tropics and middle latitudes, what would enable storms as strong as in the last interglacial, the [[Eemian]], whose evidence includes, among others, megaboulders on Bahamas.<ref>{{Cite journal|last1=Hansen|first1=J.|last2=Sato|first2=M.|last3=Hearty|first3=P.|last4=Ruedy|first4=R.|last5=Kelley|first5=M.|last6=Masson-Delmotte|first6=V.|last7=Russell|first7=G.|last8=Tselioudis|first8=G.|last9=Cao|first9=J.|date=2016-03-22|title=Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2 °C global warming could be dangerous|journal=Atmos. Chem. Phys.|volume=16|issue=6|pages=3761–3812|doi=10.5194/acp-16-3761-2016|issn=1680-7324|arxiv=1602.01393|bibcode=2016ACP....16.3761H|s2cid=9410444 |doi-access=free }}</ref><ref>{{Citation|last=Climate Science, Awareness and Solutions|title=Ice Melt, Sea Level Rise and Superstorms Video Abstract|date=2016-03-21|url=https://www.youtube.com/watch?v=JP-cRqCQRc8 |archive-url=https://ghostarchive.org/varchive/youtube/20211222/JP-cRqCQRc8 |archive-date=2021-12-22 |url-status=live|access-date=2018-01-03}}{{cbignore}}</ref>
In 2023, Hansen led a team of 18 researchers to publish a paper titled "Global Warming in the Pipeline."<ref name=":0">{{Cite journal |last1=Hansen |first1=James E |last2=Sato |first2=Makiko |last3=Simons |first3=Leon |last4=Nazarenko |first4=Larissa S |last5=Sangha |first5=Isabelle |last6=Kharecha |first6=Pushker |last7=Zachos |first7=James C |last8=von Schuckmann |first8=Karina |last9=Loeb |first9=Norman G |last10=Osman |first10=Matthew B |last11=Jin |first11=Qinjian |last12=Tselioudis |first12=George |last13=Jeong |first13=Eunbi |last14=Lacis |first14=Andrew |last15=Ruedy |first15=Reto |date=2023-02-14 |title=Global warming in the pipeline |url=https://academic.oup.com/oocc/article/doi/10.1093/oxfclm/kgad008/7335889 |journal=Oxford Open Climate Change |language=en |volume=3 |issue=1 |doi=10.1093/oxfclm/kgad008 |issn=2634-4068|doi-access=free }}</ref> In it, Hansen et al. concluded that a doubling of carbon dioxide in the atmosphere would lead to an increase of 4.8 ±1.2{{nbsp}}°C, significantly above earlier estimates.<ref name=":1">{{Cite news |last=Wallace-Wells |first=David |date=November 8, 2023 |title=The Godfather of Climate Science Turns Up the Heat |work=The New York Times |url=https://www.nytimes.com/2023/11/08/opinion/hansen-climate-warming-warning.html?unlocked_article_code=1.9Uw.o1CS.L5C2Cibp73UL&smid=url-share |access-date=November 9, 2023}}</ref> His team also concluded that the decline in global aerosol emissions from air pollution will accelerate the rate of global warming, going from an increase of 0.18 °C per decade between 1970 and 2010 to an increase of 0.27 °C per decade after 2010, with the world passing the 1.5 °C threshold before the end of the 2020s and the 2 °C threshold before 2050 without significant changes.<ref name=":0" /> The paper also concluded that sea level rise will be greater than the IPCC estimates and one of the ocean's major circulation systems could collapse before the end of the century.<ref name=":1" />
==Analysis of climate change causation==
{{Quote box
| quote =''"The first action that people should take is to use the democratic process. What is frustrating people, me included, is that democratic action affects elections but what we get then from political leaders is [[greenwash]]."''
| source = — James Hansen (March 2009)<ref name="Adam">{{cite news|url=httphttps://www.guardiantheguardian.co.ukcom/science/2009/mar/18/nasa-climate-change-james-hansen|title=Leading climate scientist: 'democratic process isn't working'|last=Adam|first=David |date=18 March 2009|publishernewspaper=guardian.co.ukThe Guardian |accessdateaccess-date=2009-03-19|location=London}}</ref>
| width =25%
| align =right
}}
Hansen notesnoted that in determining responsibility for climate change, the effect of greenhouse gas emissions on climate is not determined not by current emissions, but by accumulated emissions over the lifetime of greenhouse gases in the atmosphere.
By this measure the U.K. is still the largest single cause of climate change, followed by the U.S. and Germany, even though its current emissions are surpassed by the Peoples Republic of China.<ref name="hansen-testimony">{{cite web| url=http://www.greenpeace.org.uk/files/pdfs/climate/hansen.pdf |title=Hansen's Kingsnorth testimony |accessdate=02 February 2009 | format=PDF }}</ref>
By this measure, among major economies, as of 2009 the U.K. still had the highest cumulative per capita contribution to climate change, followed by the U.S. and Germany, even though the [[People's Republic of China]] currently produces the highest total annual emissions.<ref name="hansen-testimony">{{cite web | url=http://www.greenpeace.org.uk/files/pdfs/climate/hansen.pdf | title=Hansen's Kingsnorth testimony | access-date=February 2, 2009 | archive-url=https://web.archive.org/web/20090203050846/http://www.greenpeace.org.uk/files/pdfs/climate/hansen.pdf | archive-date=February 3, 2009 }}</ref>
On public policy, Hansen is critical of what he sees as efforts to mislead the public on the issue of climate change. He points specifically to the [[Competitive Enterprise Institute]]'s commercials with the tagline "carbon dioxide—they call it pollution, we call it life",<ref>{{cite web| url=http://www.npr.org/templates/story/story.php?storyId=5425355 |title=They Call It Pollution. We Call It Life |first=J.J. |last=Sutherland |publisher=NPR.org |date=May 23, 2006 |accessdate=02 February 2009}}</ref> and politicians who accept money from fossil fuel interests and then describe global warming as "a great hoax."<ref>{{cite web |url=http://www.columbia.edu/~jeh1/2006/DukeEdin_complete_20061121.pdf |title=The Threat to the Planet: How Can We Avoid Dangerous Human-Made Climate Change? |work=Remarks of James E. Hansen on 21 November 2006 On Acceptance of WWF Duke of Edinburgh Conservation Medal |first=James |last=Hansen |accessdate=05 February 2009 |date=21 November 2006 }}</ref> He also says that changes needed to reduce global warming do not require hardship or reduction in the quality of life, but will also produce benefits such as cleaner air and water, and growth of high-tech industries.<ref>{{cite web |url=http://www.columbia.edu/~jeh1/2006/NewSchool_20060210.pdf |title=Can We Still Avoid Dangerous Human-Made Climate Change? |date=10 February 2006 |accessdate=10 February 2009 |first=James |last=Hansen }}</ref> He was a critic of both the Clinton and George W. Bush Administrations' stances on climate change.<ref>{{cite web |url=http://www.cbsnews.com/stories/2006/03/17/60minutes/main1415985.shtml |title=Rewriting The Science |publisher=CBS News |accessdate=5 February 2009 |date=30 July 2006 |first=Daniel |last=Schorn }}</ref> With respect to addressing the potential effects of climate change, Hansen has stated in an interview in January, 2009, "We cannot now afford to put off change any longer. We have to get on a new path within this new administration. We have only four years left for Obama to set an example to the rest of the world. America must take the lead." <ref>{{cite web| url=http://www.guardian.co.uk/environment/2009/jan/18/obama-climate-change |title='We have only four years left to act on climate change - America has to lead' |first=Robin |last=McKie |date=18 January 2009 |accessdate=02 February 2009 |publisher=The Guardian }}</ref>
On public policy, Hansen is critical of what he sees as efforts to mislead the public on the issue of climate change. He points specifically to the [[Competitive Enterprise Institute]]'s commercials with the tagline "carbon dioxide—they call it pollution, we call it life",<ref>{{cite web| url=https://www.npr.org/templates/story/story.php?storyId=5425355 |title=They Call It Pollution. We Call It Life
Hansen has been particularly critical of the coal industry, stating that coal contributes the largest percentage of anthropogenic carbon dioxide into the atmosphere.<ref>{{cite web |url=http://www.columbia.edu/~jeh1/2007/IowaCoal_20071105.pdf |work=State of Iowa: Before the Iowa Utilities Board |title=Direct Testimony of James E. Hansen |accessdate=02 February 2009 }}</ref> He acknowledges that a molecule of carbon dioxide emitted from burning coal has the same effect as a molecule emitted from burning oil. The difference is where the fuel originally resides. He says that most oil comes from [[Russia]] and [[Saudi Arabia]], and that no matter how fuel-efficient automobiles become, the {{CO2}} will eventually be burned. In a 2007 testimony before the Iowa Utilities Board, he stated that the United States has a large reservoir of coal, which makes it a resource that can be controlled through action by U.S. politicians, unlike oil which is controlled by other countries.<ref>{{cite web |url=http://www.columbia.edu/~jeh1/2007/IowaCoal_20071105.pdf |work=State of Iowa: Before the Iowa Utilities Board |title=Direct Testimony of James E. Hansen |accessdate=02 February 2009 }}</ref> He has called for [[coal phase out|phasing out coal power]] completely by the year 2030.<ref>{{cite web |url=http://www.columbia.edu/~jeh1/2008/TargetCO2_20080407.pdf |title=Target Atmospheric CO2: Where Should Humanity Aim? |accessdate=02 February 2009 |format=PDF }}</ref>
| first=J.J. |last=Sutherland
| publisher=[[NPR]]
| date=May 23, 2006
| access-date=February 2, 2009}}</ref> and politicians who accept money from fossil-fuel interests and then describe global warming as "a great hoax."<ref>{{cite web |url=http://www.columbia.edu/~jeh1/2006/DukeEdin_complete_20061121.pdf |title=The Threat to the Planet: How Can We Avoid Dangerous Human-Made Climate Change? |work=Remarks of James E. Hansen on 21 November 2006 On Acceptance of WWF Duke of Edinburgh Conservation Medal |first=James |last=Hansen |publisher=[[Columbia University]]
| access-date=February 5, 2009
| date=November 21, 2006 }}</ref> He also says that changes needed to reduce global warming do not require hardship or reduction in the quality of life, but will also produce benefits such as cleaner air and water, and growth of high-tech industries.<ref>{{cite web |url=http://www.columbia.edu/~jeh1/2006/NewSchool_20060210.pdf |title=Can We Still Avoid Dangerous Human-Made Climate Change?
| date=February 10, 2006 |access-date=February 10, 2009
| first=James |last=Hansen }}</ref> He was a critic of both the [[Clinton Administration|Clinton]] and [[George W. Bush Administration]]s' stances on climate change.<ref name="cbs" /> Addressing the potential effects of climate change, Hansen has stated in an interview in January 2009, "We cannot now afford to put off change any longer. We have to get on a new path within this new administration. We have only four years left for Obama to set an example to the rest of the world. America must take the lead."<ref>{{cite news| url=https://www.theguardian.com/environment/2009/jan/18/obama-climate-change |title=We have only four years left to act on climate change – America has to lead |first=Robin |last=McKie
| date=January 18, 2009
| access-date= February 2, 2009
| newspaper=The Guardian |location=London}}</ref>
==Climate change activism==
During his testimony before the Iowa Utilities Board in 2007, Hansen likened coal trains to "death trains" and asserted that these would be "no less gruesome than if they were boxcars headed to crematoria, loaded with uncountable irreplaceable species."<ref name=NYTBlog>{{cite web |url=http://dotearth.blogs.nytimes.com/2007/11/26/holocausts/ |title=Climate, Coal and Crematoria |first=Andrew |last=Revkin |date=26 November 2007 |accessdate=02 February 2009 |publisher=The New York Times }}</ref> In response, the National Mining Association stated that his comparison "trivialized the suffering of millions" and "undermined his credibility."<ref>{{cite web| url=http://www.columbia.edu/~jeh1/NMAletters_20071121.pdf |title=Hansen's correspondence with NMA re "coal crematoria" |accessdate=02 February 2009 }}</ref><ref> "More from NASA's Hansen on coal" ''Des Moines Register'', November 7, 2007</ref> Citing the reactions of "several people" and "three of his scientific colleagues" as his primary motivation, Hansen stated that he certainly did not mean to trivialize suffering by the families who lost relatives in the [[Holocaust]] and then apologized saying he regretted that his words caused pain to some readers.<ref>{{cite web |url=http://www.columbia.edu/~jeh1/mailings/2007/20071128_AvertingOurEyes.pdf |title=Averting Our Eyes |first=James |last=Hansen |date=28 November 2007 |accessdate=06 February 2009 |publisher=James Hansen }}</ref>
=== US Senate committee testimony ===
==Honors and awards==
[[Image:James hansen09.jpg|thumb||right|Photograph taken of James Hansen at NASA's Goddard Institute for Space Studies in 2007.]]
Hansen was elected to the [[United States National Academy of Sciences|National Academy of Sciences]] in 1996 for his "development of pioneering radiative transfer models and studies of planetary atmospheres; development of simplified and three-dimensional global climate models; explication of climate forcing mechanisms; analysis of current climate trends from observational data; and projections of anthropogenic impacts on the global climate system."<ref>{{cite web |title=Directory of the National Academy of Sciences | url=http://www.nasonline.org/site/Dir/694414760?pg=vprof&mbr=1003147&returl=http%3A%2F%2Fwww.nasonline.org%2Fsite%2FDir%2F694414760%3Fpg%3Dsrch%26view%3Dbasic&retmk=search_again_link | accessdate=2007-06-19}}</ref> In 2001, he received a US $250,000 Heinz Environment Award for his research on global warming,<ref>{{cite web |title=The Heinz Awards | url=http://www.heinzawards.net/recipients/james-hansen | accessdate=2008-09-27}}</ref> and was listed as one of [[Time Magazine]]'s [[Time 100|100 Most Influential People]] in 2006. Also in 2006, the [[American Association for the Advancement of Science]] (AAAS) selected James Hansen to receive their [[Award for Scientific Freedom and Responsibility]] "for his courageous and steadfast advocacy in support of scientists' responsibilities to communicate their scientific opinions and findings openly and honestly on matters of public importance."<ref>{{cite web |url=http://www.aaas.org/aboutaaas/awards/freedom/freedom2007.shtml |title=AAAS Award for Scientific Freedom and Responsibility: James Hansen |accessdate=05 February 2009 |publisher=American Association for the Advancement of Science }}</ref>
Hansen was invited by [[Rafe Pomerance]] to testify before the [[United States Senate Committee on Energy and Natural Resources]] on June 23, 1988.<ref name="Rich">{{cite news |first=Nathaniel |last=Rich |date=5 August 2018 |title=Losing Earth: The Decade We Almost Stopped Climate Change |work=The New York Times Magazine |pages=4– |issn=0028-7822 |url=https://www.nytimes.com/interactive/2018/08/01/magazine/climate-change-losing-earth.html |archive-url=https://web.archive.org/web/20220115105222/https://www.nytimes.com/interactive/2018/08/01/magazine/climate-change-losing-earth.html |archive-date=15 January 2022 |url-status=live |url-access=limited}}</ref><ref name=besel2013>{{cite journal |last=Besel |first=Richard D. |title=Accommodating climate change science: James Hansen and the rhetorical/political emergence of global warming |journal=Science in Context |volume=26 |issue=1 |year=2013 |pages=137–152 |url=http://digitalcommons.calpoly.edu/cgi/viewcontent.cgi?article=1014&context=comm_fac |access-date=February 20, 2016 |doi=10.1017/S0269889712000312|s2cid=18364313 }}</ref> Hansen testified that "Global warming has reached a level such that we can ascribe with a high degree of confidence a cause and effect relationship between the greenhouse effect and observed warming...It is already happening now"<ref name=nyt19880624/> and "The greenhouse effect has been detected and it is changing our climate now...We already reached the point where the greenhouse effect is important."<ref name=wp19880624>{{cite news |last=Weisskopf |first=Michael |title=Scientist Says Greenhouse Effect is Setting in |newspaper=[[The Washington Post]] |date=June 24, 1988 |access-date=February 20, 2016 |url=https://www.washingtonpost.com/archive/politics/1988/06/24/scientist-says-greenhouse-effect-is-setting-in/3844f00f-42f4-420f-8811-62de6c989d8f/}}</ref> Hansen said that NASA was 99% confident that the warming was caused by the accumulation of greenhouse gases in the atmosphere and not a random fluctuation.<ref name=nyt19880624/><ref name=wp19880624/>
In 2007, Hansen shared the US $1 million [[Dan David Prize]] for "achievements having an outstanding scientific, technological, cultural or social impact on our world". In 2008, he received the [[PNC Bank]] [[Common Wealth Award of Distinguished Service]] for his "outstanding achievements" in science. At the end of 2008, Hansen was named by [[EarthSky Communications]] and a panel of 600 scientist-advisors as the ''Scientist Communicator of the Year'', citing him as an "outspoken authority on climate change" who had "best communicated with the public about vital science issues or concepts during 2008."<ref name="rossby">{{cite web |url=http://www.nasa.gov/centers/goddard/news/topstory/2009/hansen_ams.html |title=NASA Climate Scientist Honored by American Meteorological Society |accessdate=05 February 2009 |date=14 January 2009 |publisher=NASA }}</ref>
According to science historian [[Spencer R. Weart]], Hansen's testimony increased public awareness of climate change.<ref>{{cite book |last=Weart |first=Spencer R. |author-link=Spencer R. Weart |title=The Discovery of Global Warming |publisher=[[Harvard University Press]] |year=2008 |isbn=978-0-674-04497-5|title-link=The Discovery of Global Warming }}</ref> According to Richard Besel of [[California Polytechnic State University]], Hansen's testimony "was an important turning point in the history of global climate change."<ref name=besel2013/> According to Timothy M. O'Donnell of the [[University of Mary Washington]], Hansen's testimony was "pivotal," "ignited public discussion of global warming and moved the controversy from a largely scientific discussion to a full blown science policy debate," and marked "the official beginning of the global warming policy debate."<ref>{{cite journal |last=O'Donnell |first=Timothy M. |title=Of loaded dice and heated arguments: Putting the Hansen-Michaels global warming debate in context |journal=[[Social Epistemology (journal)|Social Epistemology]] |volume=14 |issue=2–3 |year=2000 |pages=109–127 |url=http://www.pitt.edu/~gordonm/Pubdeb/O'Donnell.pdf |access-date=February 20, 2016 |doi=10.1080/02691720050199199|s2cid=31213842 }}</ref> According to [[Roger A. Pielke]] of the [[National Center for Atmospheric Research]], Hansen's "call to action" "elevated the subject of global warming and the specter of associated impacts such as more hurricanes, floods, and heat waves, to unprecedented levels of attention from the public, media, and policy makers."<ref>{{cite journal |last=Pielke |first=Roger A. |title=Policy history of the US global change research program: Part I. Administrative development |journal=[[Global Environmental Change]] |volume=10 |issue=1 |year=2000 |pages=9–25 |url=http://sciencepolicy.colorado.edu/admin/publication_files/2000.09.pdf |access-date=February 20, 2016 |doi=10.1016/s0959-3780(00)00006-6|bibcode=2000GEC....10....9P }}</ref>
In 2009, Hansen was awarded the 2009 [[Carl-Gustaf Rossby Research Medal]],<ref name="rossby" /> the highest honor bestowed by the [[American Meteorological Society]], for his "outstanding contributions to climate modeling, understanding climate change forcings and sensitivity, and for clear communication of climate science in the public arena."<ref>{{cite web |url=http://www.ametsoc.org/awards/2009awardrecipients.pdf |title=AMS Awards |publisher=American Meteorological Society |accessdate=05 February 2009 }}</ref>
===Criticism of coal industry===
== Controversies ==
Hansen has been particularly critical of the [[coal industry]], stating that coal contributes the largest percentage of anthropogenic carbon dioxide into the atmosphere.<ref name="columbia.edu">{{cite web |url=http://www.columbia.edu/~jeh1/2007/IowaCoal_20071105.pdf |work=State of Iowa: Before the Iowa Utilities Board |title=Direct Testimony of James E. Hansen |access-date=February 2, 2009 }}</ref> He has called for [[coal phase out|phasing out coal power]] completely by the year 2030.<ref>{{Cite journal | doi = 10.2174/1874282300802010217 |doi-access=free| title = Target Atmospheric CO<sub>2</sub>: Where Should Humanity Aim?| journal = The Open Atmospheric Science Journal| volume = 2| issue = 1| pages = 217–231| year = 2008| last1 = Hansen | first1 = J. | author-link1 = James Hansen| last2 = Sato | first2 = M. | last3 = Kharecha | first3 = P. | last4 = Beerling | first4 = D. | author-link4 = David Beerling| last5 = Berner | first5 = R. | author-link5 = Robert Berner| last6 = Masson-Delmotte | first6 = V. | last7 = Pagani | first7 = M. | last8 = Raymo | first8 = M. |author-link8 = Maureen Raymo| last9 = Royer | first9 = D. L. | last10 = Zachos | first10 = J. C. | arxiv = 0804.1126| bibcode = 2008OASJ....2..217H| s2cid = 14890013}}</ref>
=== Charges of censorship ===
Hansen has stated that [[NASA]] administrators have tried to influence his public statements about the [[Attribution of recent climate change|causes of climate change]].<ref>{{cite web | title=Putting Some Heat on Bush | url=http://www.washingtonpost.com/wp-dyn/articles/A19162-2005Jan18.html | author = Juliet Eilperin | publisher=[[Washington Post]] | date=January 18, 2005 | accessdate=2007-06-20}}</ref><ref>{{cite web | title=Climate Expert Says NASA Tried to Silence Him | url=http://www.nytimes.com/2006/01/29/science/earth/29climate.html | author = [[Andrew Revkin]] | publisher=[[The New York Times]] | date=January 29, 2006 | accessdate=2007-06-20 |quote=They feel their job is to be this censor of information going out to the public. }}</ref> Hansen claims that NASA public relations staff were ordered to review his public statements and interviews after a December 2005 lecture at the [[American Geophysical Union]] in [[San Francisco, California|San Francisco]]. NASA responded that its policies are similar to those of any other federal agency in requiring employees to coordinate all statements with the public affairs office without exception.<ref name=ABC1>{{cite web | title=Top NASA Scientist Says He's Being Silenced on Global Warming | url=http://abcnews.go.com/WNT/story?id=1555183 | author = Bill Blakemore | publisher=[[ABC News]] | date=January 29, 2006 | accessdate=2008-06-20}}</ref> Two years after Hansen and other agency employees described a pattern of distortion and suppression of climate science by political [[wikt:appointee|appointee]]s, the agency’s inspector general found that the NASA Office of Public Affairs had mischaracterized the science of climate change intended for the public.<ref>{{cite web |url=http://www.nytimes.com/2008/06/03/science/earth/03nasa.html?em&ex=1212638400&en=27f054b906a7623c&ei=5087%0A |title=NASA Office Is Criticized on Climate Reports |publisher=The New York Times |author=Andrew C. Revkin |date=03 June 2008 }}</ref>
During his testimony before the Iowa Utilities Board in 2007, Hansen likened coal trains to "death trains" and asserted that these would be "no less gruesome than if they were boxcars headed to crematoria, loaded with uncountable irreplaceable species."<ref name=NYTBlog>{{cite news |url=http://dotearth.blogs.nytimes.com/2007/11/26/holocausts/ |title=Climate, Coal and Crematoria |first=Andrew |last=Revkin
Hansen has also appeared on ''[[60 Minutes]]'' stating that the White House edited climate-related press releases reported by federal agencies to make global warming seem less threatening.<ref name=cbs>{{cite web |title=Rewriting the Science |author=Catherine Herrick/Bill Owens |publisher=[[CBS]] | url=http://www.cbsnews.com/stories/2006/03/17/60minutes/main1415985.shtml | date=30 June 2006 | accessdate=07 February 2009 |author=Daniel Schorn }}</ref> He claimed that he was unable to speak freely without the backlash of other government officials, and that he has not experienced that level of restrictions on communicating with the public during his career.<ref name=cbs/>
| date= November 26, 2007 |access-date= February 2, 2009 |newspaper=The New York Times }}</ref> In response, the [[National Mining Association]] stated that his comparison "trivialized the suffering of millions" and "undermined his credibility."<ref>{{cite web
|url = http://www.columbia.edu/~jeh1/NMAletters_20071121.pdf
|title = Hansen's correspondence with NMA re "coal crematoria"
|access-date = February 2, 2009
|archive-url = https://web.archive.org/web/20080113185414/http://www.columbia.edu/~jeh1/NMAletters_20071121.pdf
|archive-date = January 13, 2008
}}</ref><ref>[http://ksj.mit.edu/tracker/2007/11/des-moines-register-coal-plant-permit-an More from NASA's Hansen on coal] ''[[Des Moines Register]]'' / [[Knight Science Journalism at MIT]], November 7, 2007, Retrieved November 23, 2012</ref> Citing the reactions of "several people" and "three of his scientific colleagues" as his primary motivation, Hansen stated that he certainly did not mean to trivialize suffering by the families who lost relatives in the [[Holocaust]] and then apologized, saying he regretted that his words caused pain to some readers.<ref>{{cite web |url=http://www.columbia.edu/~jeh1/mailings/2007/20071128_AvertingOurEyes.pdf |title=Averting Our Eyes |first=James |last=Hansen |date=November 28, 2007 |access-date=February 6, 2009 |publisher=James Hansen |archive-url=https://web.archive.org/web/20090224211405/http://www.columbia.edu/~jeh1/mailings/2007/20071128_AvertingOurEyes.pdf |archive-date=February 24, 2009 }}</ref>
====Mountaintop removal mining====
===Trials for fossil fuel chiefs===
In 2008 interviews with ''[[ABC News]]'', ''[[The Guardian]]'', and in a separate op-ed, Hansen has called for putting [[fossil fuel]] company executives, including the CEOs of [[ExxonMobil]] and [[Peabody Coal]], on trial for "[[high crimes]] against humanity and nature", on the grounds that these and other fossil-fuel companies had actively spread doubt and misinformation about [[global warming]], in the same way that [[tobacco]] companies tried to hide the link between smoking and cancer.<ref name=abc20ylater>{{cite web | title=Global Warming 20 Years Later| url=http://abcnews.go.com/Video/playerIndex?id=5228739&affil=wjla | author = Clayton Sandell | publisher=[[ABC News]] | date=June 23, 2008 | accessdate=2008-06-23}}</ref><ref name=guardtrial>{{cite web |url=http://www.guardian.co.uk/environment/2008/jun/23/fossilfuels.climatechange?feed=science&gusrc=rss |title=Put oil firm chiefs on trial, says leading climate change scientist |author=Ed Pilkington |publisher=The Guardian |date= 23 June 2008 |accessdate=06 February 2009 }}</ref><ref name=ww20ylater>{{cite web |url= http://www.worldwatch.org/node/5798 |title= Guest Opinion: Global Warming Twenty Years Later |accessdate= 2008-06-23 |author= James Hansen |date= 2008-06-23 |publisher= [[Worldwatch Institute]] |quote= In my opinion, these CEOs should be tried for high crimes against humanity and nature. }}</ref>
On June 23, 2009, James Hansen, along with 30 other [[protester]]s including actress [[Daryl Hannah]], was arrested on [[misdemeanor]] charges of obstructing police and impeding traffic, during a protest against [[mountaintop removal mining]] in [[Raleigh County, West Virginia]].<ref>{{cite web |url=http://www.wvpubcast.org/newsarticle.aspx?id=10144 |title=Hannah, Hansen arrested in mountaintop removal protest |work=[[West Virginia Public Broadcasting]] |date=June 23, 2009 |archive-url=https://web.archive.org/web/20110928132536/http://www.wvpubcast.org/newsarticle.aspx?id=10144 |archive-date=September 28, 2011 }}</ref> The protesters intended to enter the property of [[Massey Energy Company]], but were blocked by a crowd of several hundred coal miners and supporters.<ref>{{cite web |url=http://wvgazette.com/News/200906230449 |archive-url=https://archive.today/20120718133521/http://wvgazette.com/News/200906230449 |archive-date=July 18, 2012 |title=Daryl Hannah, scientist among 30 arrested at W.Va. mine protest |work=[[Charleston Gazette]] |date=June 23, 2009 }}</ref> Hansen said that mountaintop removal for coal mining "[provides] only a small fraction of our energy" and "should be abolished."<ref name=NYT.E>{{cite news |url=http://dotearth.blogs.nytimes.com/2009/06/23/hansen-of-nasa-arrested-in-coal-country/
===Kingsnorth power station trial===
| title=Hansen of NASA Arrested in Coal Country
In October 2007, six [[Greenpeace]] activists painted [[graffiti]] on a chimney of the [[Kingsnorth power station]] in [[Kent]], England, which cost £30,000 to remove. Hansen was called as a defense witness to testify about the danger of climate change, saying "somebody needs to step forward and say there has to be a moratorium, draw a line in the sand and say no more coal-fired power stations."<ref>{{cite web | authorlink = [[Greenpeace]] | title = Court deals Major Blow to UK coal-fired power plans | publisher = [[Greenpeace]] | date = 2008-09-10 | url = http://www.greenpeace.org/international/press/releases/court-major-blow-to-uk-coal-10092008 | accessdate = 2009-02-08}}</ref>
| work=New York Times
| date=June 23, 2009
| first=Andrew C.
| last=Revkin
| access-date=May 5, 2010}}</ref> Hansen called on President [[Barack Obama]] to abolish mountaintop coal mining.<ref>{{cite web |url=http://e360.yale.edu/content/feature.msp?id=2168 |title=A Plea To President Obama: End Mountaintop Coal Mining |date=June 22, 2009 |work=Environment 360 |publisher=[[Yale University]] |archive-url=https://web.archive.org/web/20090624081537/http://e360.yale.edu/content/feature.msp?id=2168 |archive-date=June 24, 2009 }}</ref>
After Hansen's arrest, ''New York Times'' columnist [[Andrew Revkin]] wrote: "Dr. Hansen has pushed far beyond the boundaries of the conventional role of scientists, particularly government scientists, in the environmental policy debate."<ref name=NYT.E />
===Arrest during protest in West Virginia===
On June 23, 2009, James Hansen, along with 30 other [[protester]]s including actress [[Daryl Hannah]], were arrested on [[misdemeanor]] charges of obstructing police and impeding traffic, during a protest against [[mountaintop removal mining]] in [[Raleigh County, West Virginia]].<ref>{{cite web |url=http://www.wvpubcast.org/newsarticle.aspx?id=10144 |title=Hannah, Hansen arrested in mountaintop removal protest |work=West Virginia Public Broadcasting |date=June 23, 2009 }}</ref> The protesters intended to enter the property of [[Massey Energy Company]], but were blocked by a crowd of several hundred coal miners and supporters.<ref>{{cite web |url=http://wvgazette.com/News/200906230449 |title=Daryl Hannah, scientist among 30 arrested at W.Va. mine protest |work=Charleston Gazette |date=June 23, 2009 }}</ref> Hansen said that mountaintop removal for coal mining "[provides] only a small fraction of our energy" and "should be abolished."<ref name=NYT.E>{{cite web |url=http://dotearth.blogs.nytimes.com/2009/06/23/hansen-of-nasa-arrested-in-coal-country/ |title=Hansen of NASA Arrested in Coal Country |work=New York Times |date=June 23, 2009 }}</ref> Hansen called on President [[Barack Obama]] to abolish mountaintop coal mining.<ref>{{cite web |url=http://e360.yale.edu/content/feature.msp?id=2168 |title=A Plea To President Obama: End Mountaintop Coal Mining |date=22 Jun 2009 |work=Environment 360 |publisher=[[Yale University]] }}</ref>
Hansen and about 100 other people were arrested in September 2010 in front of the [[White House]] in Washington, DC. The group was seeking a ban on mountaintop removal or [[surface mining]].<ref>{{cite news
===Capitol Power Plant Protest Controversy===
| url=http://www.latimes.com/business/nationworld/wire/sns-ap-us-mountaintop-mining-protest,0,3876315.story
In 2009, Hansen advocated the participation of citizens <ref>http://vimeo.com/3268481</ref> at a March 2 unlawful protest at the Capitol Power Plant (located in Southeast Washington, D.C.).<ref>http://www.foxnews.com/story/0,2933,501064,00.html</ref> Hansen stated "We need to send a message to Congress and the president that we want them to take the actions that are needed to preserve climate for young people and future generations and all life on the planet". Dr. John Theon, a former senior NASA atmospheric scientist and past supervisor of Hansen said "I'm not surprised ... The fact that Jim Hansen has gone off the deep end here is sad because he's a good fellow...Why he has not been fired I do not understand." United States Congressman Dana Rohrabacher (a member of the House's Committee on Science and Technology) stated "If he wants to have a demonstration concerning global warming, coming to the Capitol is not a right choice. Most of us have always thought he has been hiding behind a scientific facade, and really, he was a political activist all along." Author Chris Horner, who wrote the book "Red Hot Lies: How Global Warming Alarmists Use Threats, Fraud, and Deception to Keep You Misinformed" has stated "He's providing ample cause to question his employment on the taxpayer dime. He's clearly abused his platform provided to him by the taxpayer, principally by the way he's been exposed of manipulating and revising data with the strange coincidence of him always found on the side of exaggerating the warming." The global warming protests were ultimately hampered by the heaviest snowfall of the year, in which 15 cm of snow blanketed Washington.<ref>http://www.theaustralian.news.com.au/story/0,25197,25135000-2703,00.html</ref>
| title=About 100 arrested in DC mountaintop mining rally
| newspaper=Los Angeles Times
| agency=Associated Press }} {{dead link|date=June 2021|bot=medic}}{{cbignore|bot=medic}}</ref><ref>{{cite news |title=Police Arrest Dozens Of People Protesting Mountaintop Mining
| url=http://www.nasdaq.com/aspx/stock-market-news-story.aspx?storyid=201009271630dowjonesdjonline000389&title=police-arrest-dozens-of-people-protesting-mountaintop-mining
| publisher=Dow Jones
| work=Nasdaq
| access-date=September 27, 2010
| date=September 27, 2010}}</ref>
===Cap and trade===
===Hansen's role as a climate activist===
In 2009 Hansen spoke out against [[cap and trade]], advocating instead what he believes would be a progressive [[carbon tax]] at source carbon as oil, gas or coal, with a 100% dividend returned to citizens in equal shares, as proposed by [[Citizens' Climate Lobby]]. He has made many appearances and talks supporting the work of CCL.<ref name="James Hansen 2009" /><ref>{{cite web |first=James |last=Bone |title= Climate scientist James Hansen hopes summit will fail |work= Timesonline
| date= December 3, 2009 |url= http://www.timesonline.co.uk/tol/news/environment/article6941974.ece |archive-url= https://web.archive.org/web/20100603015313/http://www.timesonline.co.uk/tol/news/environment/article6941974.ece |url-status= dead |archive-date= June 3, 2010 |access-date= December 10, 2009}}</ref><ref>{{cite news |first=James |last=Randerson |title=Nasa climate expert makes personal appeal to Obama
Andrew Freedman, an environmental journalist and columnist at the ''[[Washington Post]]'', believes the [[American Meteorological Society]] erred in giving Hansen its 2009 [[Carl-Gustaf Rossby Research Medal]]: "By citing his 'clear communication of climate science in the public arena,' they may have actually sanctioned his political advocacy. Such advocacy... threatens to paint the AMS as having a political agenda too." <ref name=AMS> [http://voices.washingtonpost.com/capitalweathergang/2009/01/it_normally_does_not_make.html Science Group Erred Giving Hansen Top Honor], by Andrew Freedman, Washington Post, January 29, 2009 </ref> Other AMS members have also criticized the award. <ref name=AMS/>
| work= The Guardian |date= January 2, 2009 |url=https://www.theguardian.com/environment/2009/jan/02/obama-climate-change-james-hansen |access-date=December 10, 2009 |location=London}}</ref><ref name="TellTruth">James Hansen. Tell Barack Obama the Truth – The Whole Truth. {{cite web|url=http://www.columbia.edu/~jeh1/mailings/20081229_Obama_revised.pdf |title=Tell Barack Obama the Truth – The Whole Truth |access-date=2009-12-10 |archive-url=https://web.archive.org/web/20090106094410/http://www.columbia.edu/~jeh1/mailings/20081229_Obama_revised.pdf |archive-date=2009-01-06 }} accessed December 10, 2009.</ref><ref>{{cite web |first=Keith |last=Kloor
<ref> [http://dotearth.blogs.nytimes.com/2009/01/14/weather-mavens-honor-climate-maven/ "Weather Mavens Honor Climate Maven"] by [[Andrew Revkin]], NY Times, January 14, 2009 </ref>
| title=The Eye of the Storm
| work=Nature Reports Climate Change
Physicist [[Freeman Dyson]] is strongly critical of Hansen's climate-change activism. "The person who is really responsible for this overestimate of global warming is Jim Hansen. He consistently exaggerates all the dangers... Hansen has turned his science into ideology.” <ref name=DNYT> [http://www.nytimes.com/2009/03/29/magazine/29Dyson-t.html?sq=Freeman%20Dyson "The Civil Heretic"], NY Times profile of Dyson by [[Nicholas Dawidoff]], March 25, 2009 </ref> Dyson "doesn’t know what he’s talking about", Hansen responded. "He should first do his homework." <ref name=DNYT/>
| date= November 26, 2009
| url=http://www.nature.com/climate/2009/0912/full/climate.2009.124.html |access-date= December 11, 2009}}</ref>
===Retirement from NASA===
After Hansen's arrest in West Virginia, ''New York Times'' columnist [[Andrew Revkin]] wrote: "Dr. Hansen has pushed far beyond the boundaries of the conventional role of scientists, particularly government scientists, in the environmental policy debate." <ref name=NYT.E/>
Hansen retired from NASA in April 2013 after 46 years of government service, saying he planned to take a more active role in the political and legal efforts to limit [[greenhouse gases]].<ref>{{cite news|title=Climate Maverick to Quit NASA
| url=https://www.nytimes.com/2013/04/02/science/james-e-hansen-retiring-from-nasa-to-fight-global-warming.html
| newspaper=[[New York Times]]
| access-date=April 1, 2013
| first=Justin
| last=Gillis
| date=April 1, 2013
}}</ref> The same month, the [[National Center for Science Education]], an organization noted for defending the teaching of evolution in United States science classrooms, named Hansen as an advisor to support the extension of its area of concern into the teaching of climate change.<ref>{{cite web|last=National Center for Science Education|author-link=National Center for Science Education|url=http://ncse.com/news/2013/04/three-new-climate-advisors-ncse-0014796|title=Three new climate advisors for NCSE|date=April 5, 2013|access-date=April 9, 2013}}</ref>
===Keystone Pipeline===
''New Yorker'' journalist [[Elizabeth Kolbert]] believes Hansen is "increasingly isolated among climate activists." <ref name=EKNY/> Eileen Claussen, president of the [[Pew Center on Global Climate Change]], said that "I view Jim Hansen as heroic as a scientist... But I wish he would stick to what he really knows. Because I don't think he has a realistic idea of what is politically possible..." <ref name=EKNY> [[Elizabeth Kolbert]], "The Catastrophist", profile of Hansen, ''The New Yorker,'' June 29, 2009, pp. 39-45. [http://www.newyorker.com/reporting/2009/06/29/090629fa_fact_kolbert Abstract] </ref>
In a CBC interview aired in April 2013, as Canadian Natural Resources Minister [[Joe Oliver (politician)|Joe Oliver]] lobbied in Washington, DC for approval of the [[Keystone Pipeline#Keystone XL|Keystone pipeline extension]] intended to carry more [[synthetic crude oil]] from Canada's [[Athabasca Oil Sands]] to the Gulf of Mexico,<ref name=mongabay2011>{{cite news
| url=http://news.mongabay.com/2011/0906-hance_tarsands_protest.html
| title=Climate test for Obama: 1,252 people arrested over notorious oil pipeline
| publisher=Mongabay
| date=September 6, 2011}}</ref> Hansen forcefully argued against the use of these unconventional fossil fuels. According to [[Intergovernmental Panel on Climate Change]] (IPCC) and other energy organizations "there is more than twice as much carbon in the tar sands oil" than in conventional oil. Hansen argued that coal, tar sands, and tar shale should not be used as energy sources because of their carbon emissions and claimed that the completion of the Keystone pipeline would increase the extraction of oil from oil sands. He explained that the effects of climate change may not be apparent until the far future: "It's not the case where you emit something and you see the effect. We see the beginnings of the effect but the large impacts are going to be in future decades and that science is crystal clear … Effects come slowly because of the inertia of the climate system. It takes decades, even centuries to get the full response. But we know the last time the world was 2 degrees warmer, sea level was 6 meters or 20 feet higher."<ref name=neanderthal27april2013>{{cite news
| url=https://www.cbc.ca/news/politics/top-u-s-climate-expert-calls-conservatives-neanderthal-1.1367144?cmp=rss
| title=Top U.S. climate expert calls Conservatives 'Neanderthal' Former NASA scientist James Hansen fires back at Natural Resources Minister Joe Oliver
| first=Meagan
| last=Fitzpatrick
| publisher=CBC News
| date=April 27, 2013
}}</ref> Hansen urged President Obama to reject the [[Keystone Pipeline#Keystone XL|Keystone pipeline extension]] intended to carry more [[synthetic crude oil]] from Canada's [[Athabasca Oil Sands]] to the Gulf of Mexico.<ref name="mongabay2011" /> On February 13, 2013, Hansen was again arrested at the White House, along with Daryl Hannah and [[Robert F. Kennedy, Jr.]], during a further protest against the proposed Keystone pipeline extension.<ref name="dhxl">{{cite news|author=Suzanne Goldenberg|date=February 13, 2013|title=Daryl Hannah leads celebrity Keystone XL protest at White House gates|work=The Guardian|access-date=April 13, 2013|url=https://www.theguardian.com/environment/2013/feb/13/daryl-hannah-keystone-xl-protest-obama|location=London}}</ref>
===Proposed solutions===
''New York Times'' climate columnist Christa Marshall asks if Hansen still matters in the ongoing climate debate, noting that he "has irked many longtime supporters with his scathing attacks against President Obama's plan for a [[cap-and-trade]] system." <ref name=CMa> [http://www.nytimes.com/cwire/2009/07/14/14climatewire-does-nasas-james-hansen-still-matter-in-clim-82897.html?pagewanted=all "Does NASA's James Hansen Still Matter in Climate Debate? "], by Christa Marshall, New York Times Climate Wire, published July 14, 2009 </ref> "The right wing loves what he's doing," said [[Joseph Romm]], a climate expert at the [[Center for American Progress]], an influential [[think tank]] with ties to the [[Obama administration]]. <ref name=CMa/> Hansen said that he had to speak out, since few others could explain the links between politics and the climate models. "You just have to say what you think is right," he said. <ref name=CMa/>
Recently Hansen stated his support for a revenue-neutral [[fee and dividend]] system to impose a [[carbon price|price on carbon]] that returns the money collected from the fossil fuel industry equally to all legal residents of the United States. In an interview on CBC television on March 3, 2015, Dr Hansen stated "The solution [to climate change] has to be a rising price on carbon and then the really dirty fuels like tar sands would fall on the table very quickly. They make no sense at all if you look at it from an economic-wide perspective. If we would simply put a fee on carbon – you would collect from the fossil fuel companies at the source (the domestic mines or the ports of entry) and then distribute that money to the public, an equal amount to all legal residents, that would begin to make the prices honest. And that's what the economy needs in order to be most efficient. Right now the external costs of fossil fuels are borne completely by the public. If your child gets asthma, you pay the bill, the fossil fuel company doesn't. What we need is to make the system honest."<ref>
==References==
{{cite web| url = http://www.cbc.ca/player/News/TV+Shows/Power+%26+Politics+with+Evan+Solomon/ID/2656936485/| archive-url = https://web.archive.org/web/20150402095027/http://www.cbc.ca/player/News/TV+Shows/Power+%26+Politics+with+Evan+Solomon/ID/2656936485/| archive-date = 2015-04-02| title = Power and Politics with Evan Solomon - Power and Politics - CBC Player}}</ref>
{{reflist|2}}
At the end of 2008, Hansen stated five priorities that he felt then President-elect Barack Obama should adopt "for solving the climate and energy problems, while stimulating the economy": [[efficient energy use]], [[renewable energy]], a [[smart grid]], [[generation IV reactor|generation IV nuclear reactors]] and [[carbon capture and storage]]. Regarding nuclear, he expressed opposition to the [[Yucca Mountain nuclear waste repository]], stating that the $25 Billion (US) surplus held in the [[Nuclear Waste Policy Act|Nuclear Waste Fund]] "should be used to develop [[Integral Fast Reactor|fast reactors]] that consume nuclear waste, and [[liquid fluoride thorium reactor|thorium reactors]] to prevent the creation of new long-lived nuclear waste."<ref name="TellTruth" />
==External links==
In 2009, Hansen wrote an open letter to President [[Barack Obama|Obama]] where he advocated a "Moratorium and phase-out of coal plants that do not capture and store CO<sub>2</sub>".<ref name="James Hansen 2009">{{cite web|url=http://www.columbia.edu/~jeh1/mailings/20081229_DearMichelleAndBarack.pdf |title=James Hansen. Letter to Obama |access-date=December 10, 2009 |archive-url=https://web.archive.org/web/20090126201600/http://www.columbia.edu/~jeh1/mailings/20081229_DearMichelleAndBarack.pdf |archive-date=January 26, 2009 }}</ref> In his first book ''Storms of My Grandchildren'', similarly, Hansen discusses his ''Declaration of Stewardship'', the first principle of which requires "a moratorium on coal-fired power plants that do not capture and [[Carbon sequestration|sequester carbon]] dioxide".<ref>{{cite book |author=Hansen, James |title=Storms of My Grandchildren |publisher=Bloomsbury Publishing |location=London |date=2009 |isbn=978-1-4088-0745-3 |page=242 }}</ref>
{{Portalpar|Sustainable development|Sustainable development.svg}}
{{EnergyPortal}}
* [http://www.columbia.edu/~jeh1/ James Hansen's homepage], [[Columbia University]]
* [http://www.giss.nasa.gov/staff/jhansen.html James Hansen biography], [[Goddard Institute for Space Studies|GISS]]
* [http://www.cooperativeresearch.org/entity.jsp?entity=james_e._hansen_1 James Hansen timeline], History Commons
* [http://pubs.giss.nasa.gov/authors/jhansen.html Publications by James E. Hansen], this index contains links to full articles
*{{cite web |title=Interview of James Hansen by Spencer Weart on November 27, 2000 |work=Niels Bohr Library & Archives |publisher=American Institute of Physics, College Park, MD USA | url=http://www.aip.org/history/ohilist/24309_2.html |accessdate=07 February 2009 }}
*{{cite web |url=http://earthobservatory.nasa.gov/Features/GISSTemperature/ |title=Earth's Temperature Tracker |author=David Herring |date=05 November 2007 |accessdate=11 February 2009 |publisher=NASA |work=Earth Observatory }}
* {{cite web
|date=February 2005
|title=NASA GISS: Science Briefs: Trial of the Century: Co-Conspirators Convicted
|publisher=NASA GISS website
|author=Hansen, J.
|url=http://www.giss.nasa.gov/research/briefs/hansen_11/
|accessdate=02 August 2009}}
* {{cite web
|date=February 2006, rev. February 2007
|title=NASA GISS: Science Briefs: Trial of the Century – Act II
|publisher=NASA GISS website
|author=Hansen, J.
|url=http://www.giss.nasa.gov/research/briefs/hansen_12/
|accessdate=02 August 2009}}
In March 2013, Hansen co-authored a paper in ''[[Environmental Science & Technology]]'', entitled "Prevented mortality and greenhouse gas emissions from historical and projected nuclear power". The paper examined mortality rates per unit of electrical power produced from [[fossil fuels]] (coal and natural gas) as well as [[nuclear power]]. It estimated that 1.8 million air pollution-caused deaths were prevented worldwide between 1971 and 2009, through the use of nuclear power instead of fossil fuels. The paper also concluded that the emission of some 64 billion tonnes of carbon dioxide equivalent were avoided by nuclear power use between 1971 and 2009. Looking to the future, between 2010 and 2050, it was estimated that nuclear could additionally avoid up to 420,000 to 7 million premature deaths and 80 to 240 billion tonnes of greenhouse gas emissions.<ref>{{cite journal |title=Prevented Mortality and Greenhouse Gas Emissions from Historical and Projected Nuclear Power |first1=Pushker A.|last1=Kharecha|first2=James E.|last2=Hansen |date=March 15, 2013 |volume=47 |issue=9 |pages=4889–4895 |journal=Environ. Sci. Technol. |doi=10.1021/es3051197 |pmid = 23495839|bibcode=2013EnST...47.4889K |doi-access=free |hdl=2060/20140017100 |hdl-access=free }}</ref>
<!--
* [http://www.washingtonpost.com/wp-dyn/articles/A19162-2005Jan18.html "Scientist Inspires Anger, Awe for Challenges on Global Warming"], [[Washington Post]]
* [http://www.nytimes.com/2006/01/29/science/earth/29climate.html?ex=1296190800&en=28e236da0977ee7f&ei=5088&partner=rssnyt&emc=rss "Climate Expert Says NASA Tried to Silence Him"], [[New York Times]]
* [http://www.onpointradio.org/shows/2006/02/20060203_a_main.asp "NASA and Global Warming"], audio interview with [[WBUR]] OnPoint
* [http://www.washingtonpost.com/wp-dyn/content/article/2006/02/10/AR2006021001766.html?nav=rss_politics "Censorship Is Alleged at NOAA"], [[Washington Post]]
* [http://www.realclimate.org/index.php?p=243 "Hansen in the New York Times"], [[RealClimate]]
* [http://www.time.com/time/archive/preview/0,10987,1156577,00.html "The Political Science Test"], [[Time (magazine)|TIME]]
* [http://www.nytimes.com/2006/07/22/science/22nasa.html Sequence of stories in The New York Times, from January to July 2006, covering the NASA censorship controversy] not available to non-subscribers -->
This paper elicited a critical response to Kharecha and Hansen's analysis, from an international group of senior academic energy policy analysts, including [[Benjamin Sovacool]], [[M.V. Ramana]], [[Mark Z. Jacobson]], and [[Mark Diesendorf]]. They asserted that nuclear power needs large subsidies to be economically viable, and typically there are substantial construction delays and cost overruns associated with nuclear plants. Sovacool et al. also claim that Kharecha and Hansen's estimates of [[Chernobyl Disaster]] mortalities is very low, which biases their conclusions. All of these factors are said to make Kharecha and Hansen's article "incomplete and misleading".<ref>{{Cite journal |url=http://www.nirs.org/climate/sovacool-et-al-hansen.pdf |title=Comment on "Prevented Mortality and Greenhouse Gas Emissions from Historical and Projected Nuclear Power" |first1=B.K.|last1=Sovacool|first2=M.V.|last2=Ramana|first3=M.Z.|last3=Jacobson|first4=M.|last4=Diesendorf | display-authors=etal |date=May 22, 2013 |volume=47 |issue=12 |pages=6715–6717 |journal=Environ. Sci. Technol. |bibcode=2013EnST...47.6715S |doi=10.1021/es401667h |pmid=23697811 }}</ref> Kharecha and Hansen countered that all the data these scientists use to make their criticism, "lacks credibility".<ref>{{ cite journal |title=Response to Comment on "Prevented Mortality and Greenhouse Gas Emissions from Historical and Projected Nuclear Power" |first1=P.A.|last1=Kharecha|first2=J.E.|last2=Hansen|date=May 22, 2013 |volume=47 |issue = 12|pages=6718–6719 |journal=Environ. Sci. Technol. |doi=10.1021/es402211m |pmid=23697846 |bibcode=2013EnST...47.6718K |hdl=2060/20140017702 |s2cid=206971716 |hdl-access=free }}</ref>
===Video===
* [http://www.democracynow.org/2008/3/21/censoring_science_inside_the_political_attack James Hansen interview on ''Democracy Now!'' program], March 21, 2008
* [http://www.soes.soton.ac.uk/resources/collection/seminars/hansen/Hansen.html ''The Threat to the Planet: The Dark and Bright Sides of Global Warming'] A seminar given by James Hansen at the [http://www.noc.soton.ac.uk '' National Oceanography Centre, Southampton, UK] February 6 2008
In 2013, Hansen and three other leading climate experts wrote an open letter to policy makers, saying that "continued opposition to nuclear power threatens humanity's ability to avoid dangerous climate change."<ref>{{cite news| url=http://edition.cnn.com/2013/11/03/world/nuclear-energy-climate-change-scientists-letter/index.html | work=CNN | title=Top climate change scientists issue open letter to policy influencers – CNN.com | date=November 3, 2013}} The letter was signed by Hansen, [[Ken Caldeira]], [[Kerry Emanuel]], and [[Tom Wigley]].</ref> The reaction from [[anti-nuclear]] environmental groups (e.g. the [[Natural Resources Defense Council]], [[Sierra Club]], and [[Greenpeace]]) was negative, citing [[nuclear safety and security]] issues, and the [[economics of nuclear power plants]].<ref>{{cite web |url=http://grist.org/news/more-nukes-are-you-kidding-enviros-push-back-against-hansens-call/ |title=More nukes? Are you kidding? Enviros push back against Hansen's call |first1=John|last1=Upton |date=November 7, 2013 |website=[[Grist (magazine)|Grist]] |access-date=December 20, 2015}}</ref>
Together with [[Michael Shellenberger]], Hansen began touring the world in the late 2010s, providing evidence for the climatic benefits of nuclear energy and to bring attention to the $2 trillion the US has spent on "new renewables" that despite the cost have not even caught up to nuclear in annual electricity generation, an issue reflected in Germany and elsewhere.<ref>{{cite web | url=https://klimatv.dk/james-hansen-michael-shellenberger-nuclear-power-are-renewables-enough/ | title=James Hansen & Michael Shellenberger: Nuclear Power? Are Renewables Enough? – KlimaTV | date=November 17, 2017 }}</ref><ref>{{cite web|url=https://www.congress.gov/116/meeting/house/110941/witnesses/HHRG-116-CN00-Wstate-ShellenbergerM-20200728.pdf|title=Testimony of Michael D. Shellenberger, Founder and President, Environmental Progress}}</ref>
<br>
{{global warming}}
===Political interference at NASA===
In 2006, Hansen alleged that [[NASA]] administrators had attempted to influence his public statements about the [[Attribution of recent climate change|causes of climate change]].<ref>{{cite news | title=Climate Expert Says NASA Tried to Silence Him | url=https://www.nytimes.com/2006/01/29/science/earth/29climate.html | author = Andrew Revkin | newspaper=The New York Times | date=January 29, 2006 | access-date=June 20, 2007 |quote=They feel their job is to be this censor of information going out to the public. }}</ref> Hansen said that NASA public relations staff were ordered to review his public statements and interviews after a December 2005 lecture at the [[American Geophysical Union]] in [[San Francisco, California|San Francisco]]. NASA responded that its policies are similar to those of any other federal agency in requiring employees to coordinate all statements with the public affairs office without exception.<ref name=ABC1>{{cite web | title=Top NASA Scientist Says He's Being Silenced on Global Warming
| url=https://abcnews.go.com/WNT/story?id=1555183
| author = Bill Blakemore
| publisher=ABC News
| date=January 29, 2006
| access-date=June 20, 2008}}</ref> Two years after Hansen and other agency employees described a pattern of distortion and suppression of climate science by political [[wikt:appointee|appointees]], the agency's inspector general confirmed that such activities had taken place, with the NASA Office of Public Affairs having "reduced, marginalized or mischaracterized climate change science made available to the general public".<ref>{{cite news |url = https://www.nytimes.com/2008/06/03/science/earth/03nasa.html|title = NASA Office Is Criticized on Climate Reports|newspaper = [[The New York Times]] | author = Andrew C. Revkin|date = June 3, 2008}}</ref>
In June 2006, Hansen appeared on ''[[60 Minutes]]'' stating that the George W. Bush White House had edited climate-related press releases reported by federal agencies to make global warming seem less threatening.<ref name=cbs>{{cite news
| title=Rewriting the Science |author=Catherine Herrick / Bill Owens
| publisher=CBS
| url=https://www.cbsnews.com/news/rewriting-the-science/
| date=June 30, 2006
| access-date= February 7, 2009
}}</ref> He also stated that he was unable to speak freely without the backlash of other government officials, and that he had not experienced that level of restrictions on communicating with the public during his career.<ref name=cbs />
===Trials for energy company executives===
In 2008 interviews with ''[[ABC News (United States)|ABC News]]'', ''[[The Guardian]]'', and in a separate op-ed, Hansen has called for putting [[fossil fuel]] company executives, including the CEOs of [[ExxonMobil]] and [[Peabody Coal]], on trial for "[[high crimes]] against humanity and nature", on the grounds that these and other fossil-fuel companies had actively spread doubt and misinformation about [[global warming]], in the same way that [[tobacco]] companies tried to hide the link between smoking and cancer.<ref name=abc20ylater>{{cite web | title=Global Warming 20 Years Later| url=https://abcnews.go.com/Video/playerIndex?id=5228739&affil=wjla | author = Clayton Sandell | publisher=[[ABC News (United States)|ABC News]] | date=June 23, 2008 | access-date=2008-06-23}}</ref><ref name=guardtrial>{{cite news |url=https://www.theguardian.com/environment/2008/jun/23/fossilfuels.climatechange?feed=science&gusrc=rss |title=Put oil firm chiefs on trial, says leading climate change scientist |author=Ed Pilkington |newspaper=The Guardian |date= June 23, 2008 |access-date=February 6, 2009 | location=London}}</ref><ref name=ww20ylater>{{cite web |url= http://www.worldwatch.org/node/5798 |title= Guest Opinion: Global Warming Twenty Years Later |access-date= 2008-06-23 |author= James Hansen |date= 2008-06-23 |publisher= [[Worldwatch Institute]] |quote= In my opinion, these CEOs should be tried for high crimes against humanity and nature. |archive-date= December 8, 2015 |archive-url= https://web.archive.org/web/20151208113436/http://www.worldwatch.org/node/5798 }}</ref>
===Arrest at 2011 demonstration===
[[File:NASA Scientist James Hansen Arrested.jpg|thumb|upright|James Hansen arrested at a demonstration outside the [[White House]], August 29, 2011]]Hansen and 1,251 other activists were arrested at a two week long protest in August and September 2011, in front of the White House. Hansen urged President Obama to reject the [[Keystone Pipeline#Keystone XL|Keystone pipeline extension]] intended to carry more [[synthetic crude oil]] from Canada's [[Athabasca Tar Sands]] to the Gulf of Mexico.<ref name="mongabay2011" /> On February 13, 2013, Hansen was again arrested at the White House, along with Daryl Hannah and [[Robert F. Kennedy, Jr.]], during a further protest against the proposed Keystone pipeline extension.<ref name="dhxl" />
===Criticism===
In June 2009, ''[[The New Yorker|New Yorker]]'' journalist [[Elizabeth Kolbert]] wrote that Hansen is "increasingly isolated among climate activists."<ref name=EKNY /> [[Eileen Claussen]], president of the [[Pew Center on Global Climate Change]], said that "I view Jim Hansen as heroic as a scientist.... But I wish he would stick to what he really knows. Because I don't think he has a realistic idea of what is politically possible, or what the best policies would be to deal with this problem."<ref name=EKNY>{{cite magazine| first=Elizabeth| last=Kolbert| title=The Catastrophist| magazine=The New Yorker| date= June 29, 2009| url=https://www.newyorker.com/magazine/2009/06/29/the-catastrophist}}</ref>
In July 2009, ''New York Times'' climate columnist Christa Marshall asked if Hansen still matters in the ongoing climate debate, noting that he "has irked many longtime supporters with his scathing attacks against President Obama's plan for a [[cap-and-trade]] system."<ref name=CMa>{{cite news |url=https://www.eenews.net/stories/80274 |title=Does NASA's James Hansen Still Matter in Climate Debate? |first= Christa |last=Marshall |work=Climatewire |date= July 14, 2009}}</ref> "The right wing loves what he's doing," said [[Joseph Romm]], a senior fellow at the [[Center for American Progress]], a liberal [[think tank]].<ref name=CMa /> Hansen said that he had to speak out, since few others could explain the links between politics and the climate models. "You just have to say what you think is right," he said.<ref name=CMa />
==Honors and awards==
Hansen was elected to the [[United States National Academy of Sciences|National Academy of Sciences]] in 1996 for his "development of pioneering radiative transfer models and studies of planetary atmospheres; development of simplified and three-dimensional global climate models; explication of climate forcing mechanisms; analysis of current climate trends from observational data; and projections of anthropogenic impacts on the global climate system."<ref>{{cite web |title=Directory of the National Academy of Sciences | url=http://www.nasonline.org/site/Dir/694414760?pg=vprof&mbr=1003147&returl=http%3A%2F%2Fwww.nasonline.org%2Fsite%2FDir%2F694414760%3Fpg%3Dsrch%26view%3Dbasic&retmk=search_again_link | access-date=2007-06-19}}</ref> In 2001, he received the 7th Annual [[Heinz Award]] in the Environment (endowed with US$250,000) for his research on global warming,<ref>{{cite web |title=The Heinz Awards, James Hansen profile | url=http://www.heinzawards.net/recipients/james-hansen | access-date=2008-09-27}}</ref> and was listed as one of [[Time (magazine)|''Time'' magazine]]'s [[Time 100|100 Most Influential People]] in 2006. Also in 2006, the [[American Association for the Advancement of Science]] (AAAS) selected James Hansen to receive its [[Award for Scientific Freedom and Responsibility]] "for his courageous and steadfast advocacy in support of scientists' responsibilities to communicate their scientific opinions and findings openly and honestly on matters of public importance."<ref>{{cite web |url=http://www.aaas.org/aboutaaas/awards/freedom/freedom2007.shtml |title=AAAS Award for Scientific Freedom and Responsibility: James Hansen |access-date=February 5, 2009 |publisher=American Association for the Advancement of Science }}</ref>
In 2007, Hansen shared the US$1-million [[Dan David Prize]] for "achievements having an outstanding scientific, technological, cultural or social impact on our world". In 2008, he received the [[PNC Bank]] [[Common Wealth Award of Distinguished Service]] for his "outstanding achievements" in science. At the end of 2008, Hansen was named by [[EarthSky Communications]] and a panel of 600 scientist-advisors as the ''Scientist Communicator of the Year'', citing him as an "outspoken authority on climate change" who had "best communicated with the public about vital science issues or concepts during 2008."<ref name="rossby">{{cite web |url=http://www.nasa.gov/centers/goddard/news/topstory/2009/hansen_ams.html |title=NASA Climate Scientist Honored by American Meteorological Society |access-date=February 5, 2009 |date=January 14, 2009 |publisher=NASA |archive-date=October 19, 2017 |archive-url=https://web.archive.org/web/20171019193341/http://www.nasa.gov/centers/goddard/news/topstory/2009/hansen_ams.html |url-status=dead }}</ref>
In 2009, Hansen was awarded the 2009 [[Carl-Gustaf Rossby Research Medal]],<ref name="rossby" /> the highest honor bestowed by the [[American Meteorological Society]], for his "outstanding contributions to climate modeling, understanding climate change forcings and sensitivity, and for clear communication of climate science in the public arena."<ref>{{cite web |url=http://www.ametsoc.org/awards/2009awardrecipients.pdf |title=AMS Awards |publisher=American Meteorological Society |access-date=February 5, 2009 |archive-url=https://web.archive.org/web/20090206121400/http://ametsoc.org/awards/2009awardrecipients.pdf |archive-date=2009-02-06 }}</ref>
Andrew Freedman wrote in ''[[The Washington Post]]'' that the Society had erred in giving Hansen the medal: "His body of work is not at issue... Rather, the problem arises due to the AMS' recognition of Hansen's public communication work on climate change."<ref name=AMS>{{cite news |url=http://voices.washingtonpost.com/capitalweathergang/2009/01/it_normally_does_not_make.html
|archive-url=https://web.archive.org/web/20100106121206/http://voices.washingtonpost.com/capitalweathergang/2009/01/it_normally_does_not_make.html
|url-status=dead
|archive-date=January 6, 2010
| title=Science Group Erred Giving Hansen Top Honor |first=Andrew |last=Freedman |newspaper= Washington Post |date= January 29, 2009}}</ref>
Hansen won the 2010 [[Sophie Prize]], set up in 1997 by Norwegian [[Jostein Gaarder]], the author of the 1991 best-selling novel and teenagers' guide to philosophy ''[[Sophie's World]]'',<ref>{{cite news |url=https://www.reuters.com/article/idUSTRE63636N20100407 |title=Climate scientist Hansen wins $100,000 prize |work=Reuters |access-date=April 7, 2010 | date=April 7, 2010}}</ref> for his " key role for the development of our understanding of human-induced climate change."
''[[Foreign Policy]]'' named Hansen one of its 2012 FP Top 100 Global Thinkers "for sounding the alarm on climate change, early and often".<ref>{{cite web |url=https://foreignpolicy.com/articles/2012/11/26/the_fp_100_global_thinkers?page=0,10#thinker11 |title=The FP Top 100 Global Thinkers |date=November 26, 2012 |work=Foreign Policy |access-date=November 28, 2012 |archive-date=November 30, 2012 |archive-url=https://web.archive.org/web/20121130221322/http://www.foreignpolicy.com/articles/2012/11/26/the_fp_100_global_thinkers?page=0,33#thinker11 }}</ref>
In December 2012, Hansen received the [[Commonwealth Club of California]]'s annual [[Stephen Schneider (scientist)|Stephen H. Schneider]] Award for Outstanding Climate Science Communications at a ceremony in San Francisco<ref>{{cite news |url= http://blog.sfgate.com/energy/2012/12/05/climate-guru-slams-cap-and-trade/ |title=Climate guru slams cap and trade
| first= David R |last= Baker
| work=San Francisco Chronicle
| date= December 5, 2012
| publisher=Hearst Newspapers
| access-date=January 1, 2013}}</ref>
On November 7, 2013, Hansen received the [[Joseph Priestley]] Award at [[Dickinson College]] in Carlisle, Pennsylvania "...for his work advancing our understanding of climate change, including the early application of numerical models to better understand observed climate trends and to project humans' impact on climate, and for his leadership in promoting public understanding of climate and linking the knowledge to action on climate policy." He delivered a lecture, entitled, "White House Arrest and the Climate Crisis," later that same day at Anita Tuvin Schlechter Auditorium on the college's campus.<ref>{{cite web | url=http://www.dickinson.edu/news/article/878/sounding_the_alarm | title=Sounding the Alarm | work=[[Dickinson College]] | date=November 7, 2013 | access-date=March 3, 2014}}</ref>
James Hansen was co-winner with climatologist [[Syukuro Manabe]] of the [[BBVA Foundation Frontiers of Knowledge Award]] in the Climate Change category in the ninth edition (2016) of the awards. The two laureates were separately responsible for constructing the first computational models with the power to simulate climate behavior. Decades ago, they correctly predicted how much Earth's temperature would rise due to increasing atmospheric {{CO2}}. The scores of models currently in use to chart climate evolution are heirs to those developed by Manabe and Hansen.<ref>{{Cite web|url=https://news.climate.columbia.edu/2017/01/10/james-hansen-honored-for-pioneering-work-in-climate-change-modeling/|title = James Hansen Honored for Pioneering Work in Climate Change Modeling|date = January 10, 2017}}</ref>
In June 2018, Hansen was named joint winner, with [[Veerabhadran Ramanathan]], of Taiwan's [[Tang Prize]]. Hansen's prize had a total value of NT$25 million.<ref>{{cite news|url=http://focustaiwan.tw/news/aedu/201806180001.aspx|newspaper=Focus Taiwan News Channel|title=Hansen, Ramanathan win Tang Prize in sustainable development|date=June 18, 2018}}</ref>
== Publications ==
{{Scholia}}
Over 160 publications have been authored by James Hansen. Since 2020, he has published observations and commentary at [https://www.redgreenandblue.org redgreenandblue.org], averaging approximately once per month.<ref>{{Cite web|title=Dr James Hansen Archives|url=http://redgreenandblue.org/tag/dr-james-hansen/|access-date=2021-08-09|website=Red, Green, and Blue|language=en-US}}</ref>
*{{Cite book |last=Hansen |first=James E. |title=Storms of My Grandchildren: The Truth About the Coming Climate Catastrophe and Our Last Chance to Save Humanity |publisher=[[Bloomsbury Publishing]] |location=New York |year=2009 |isbn=978-1-60819-200-7|title-link=Storms of My Grandchildren }}
== See also ==
{{Portal bar|Energy|Global warming}}
== References ==
{{Reflist}}
==Further reading==
* {{cite book |title=Censoring Science: Inside the Political Attack on Dr. James Hansen and the Truth of Global Warming |last=Bowen |first=Mark |author-link=Mark Bowen (writer) |date=2008 |publisher=[[Dutton Penguin|Dutton]] |location=New York |isbn=978-0-525-95014-1 |url-access=registration |url=https://archive.org/details/censoringscience00bowe }}
== External links ==
{{Commons category}}
* {{IMDb name|2310230}}
* [http://csas.ei.columbia.edu/ Program on Climate Science, Awareness and Solutions] at the Earth Institute, Columbia University
* {{cite web|archive-url=https://web.archive.org/web/20131113060351/http://eesc.columbia.edu/faculty/james-e-hansen|url=http://eesc.columbia.edu/faculty/james-e-hansen|title= James Hansen|archive-date=2013-11-13}} Directory entry at the Department of Earth and Environmental Sciences, Columbia University
* {{cite web|archive-url=https://web.archive.org/web/20041015153937/http://www.giss.nasa.gov/staff/jhansen.html|url=http://www.giss.nasa.gov/staff/jhansen.html|title= James Hansen|archive-date=2004-10-15}} Directory entry at the NASA Goddard Institute for Space Studies
* {{TED speaker}}
* [http://www.c-span.org/person/?jamesehansen James Hansen] on [[C-SPAN]]
* [https://www.youtube.com/watch?v=S7z61UZoppM ''James Hansen - Scientific Reticence: A Threat to Humanity and Nature'']. Press Conference in Bonn during COP23, 2017-11-19 (24 min). From [http://climatematters.tv/ ''ClimateMatters.TV''] series of [http://www.upfsi.org/ United Planet Faith and Science Initiative] {{Webarchive|url=https://web.archive.org/web/20180206222212/http://www.upfsi.org/ |date=February 6, 2018 }}.
* {{Scopus|id=7404334532}}
{{Clear}}
{{Global warming|state=collapsed}}
{{GSFC|state=collapsed}}
{{Tang Prize winners}}
{{Portal bar|Biography|United States|Global warming|Earth sciences}}
{{Authority control}}
{{DEFAULTSORT:Hansen, James}}
[[Category:American climatologists]]
[[Category:American climate activists]]
[[Category:Atmospheric physicists]]
[[Category:20th-century American physicists]]
[[Category:21st-century American physicists]]
[[Category:Goddard Space Flight Center people]]
[[Category:NASA people]]
[[Category:Members of the United States National Academy of Sciences]]
[[Category:Carl-Gustaf Rossby Research Medal recipients]]
[[Category:Science activists]]
[[Category:American sustainability advocates]]
[[Category:Sierra Club awardees]]
[[Category:University of Iowa alumni]]
[[Category:People from Denison, Iowa]]
[[Category:1941 births]]
[[Category:Members of the National Academy of Sciences]]
[[Category:American physicists]]
[[Category:Danish Americans]]
[[Category:Living people]]
[[Category:NASA personnel]]
[[Category:Sustainability advocates]]
[[Category:Action on climate change]]
[[Category:Climate change]]
[[Category:Climate change policy]]
[[Category:Energy policy]]
[[Category:Global warming]]
[[Category:Climatologists]]
[[Category:People from Crawford County, Iowa]]
[[de:James E. Hansen]]
[[fr:James Hansen]]
[[it:James Hansen]]
[[hu:James Hansen]]
[[no:James Hansen]]
[[simple:James Hansen]]
[[fi:James Hansen]]