James Edward Hansen (born March 29, 1942) is an American
adjunct professor directing the Program on Climate Science, Awareness and Solutions of the
Earth Institute
{{Infobox organization
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, image = Ei blue1.gif
, map_size =
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at
Columbia University
Columbia University (also known as Columbia, and officially as Columbia University in the City of New York) is a private research university in New York City. Established in 1754 as King's College on the grounds of Trinity Church in Manhatt ...
. He is best known for his research in
climatology
Climatology (from Greek , ''klima'', "place, zone"; and , ''-logia'') or climate science is the scientific study of Earth's climate, typically defined as weather conditions averaged over a period of at least 30 years. This modern field of study ...
, his 1988 Congressional testimony on
climate change
In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to ...
that helped raise broad awareness of
global warming
In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...
, and his advocacy of action to avoid dangerous climate change.
In recent years he has become a climate
activist to
mitigate the effects of global warming, on a few occasions leading to his arrest.
Early life and education
Hansen was born in
Denison,
Iowa
Iowa () is a state in the Midwestern region of the United States, bordered by the Mississippi River to the east and the Missouri River and Big Sioux River to the west. It is bordered by six states: Wisconsin to the northeast, Illinois to th ...
, to James Ivan Hansen and Gladys Ray Hansen. He was trained in physics and astronomy in the
space science program of
James Van Allen
James Alfred Van Allen (September 7, 1914August 9, 2006) was an American space scientist at the University of Iowa. He was instrumental in establishing the field of magnetospheric research in space.
The Van Allen radiation belts were named aft ...
at the
University of Iowa
The University of Iowa (UI, U of I, UIowa, or simply Iowa) is a public research university in Iowa City, Iowa, United States. Founded in 1847, it is the oldest and largest university in the state. The University of Iowa is organized into 12 col ...
. He obtained a
B.A.
Bachelor of arts (BA or AB; from the Latin ', ', or ') is a bachelor's degree awarded for an undergraduate program in the arts, or, in some cases, other disciplines. A Bachelor of Arts degree course is generally completed in three or four yea ...
in Physics and Mathematics with highest distinction in 1963, an
M.S.
A Master of Science ( la, Magisterii Scientiae; abbreviated MS, M.S., MSc, M.Sc., SM, S.M., ScM or Sc.M.) is a master's degree in the field of science awarded by universities in many countries or a person holding such a degree. In contrast to ...
in Astronomy in 1965 and a
Ph.D.
A Doctor of Philosophy (PhD, Ph.D., or DPhil; Latin: or ') is the most common degree at the highest academic level awarded following a course of study. PhDs are awarded for programs across the whole breadth of academic fields. Because it is ...
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
, mottoeng = Freedom of academic culture
, established =
, type = Public (National)
, endowment = ¥ 316 billion (2.4 billion USD)
, faculty = 3,480 (Teaching Staff)
, administrative_staff = 3,978 (Total Staff)
, students = 22 ...
and in the Department of Astronomy at the
University of Tokyo
, abbreviated as or UTokyo, is a public research university located in Bunkyō, Tokyo, Japan. Established in 1877, the university was the first Imperial University and is currently a Top Type university of the Top Global University Project b ...
. He then began work at the
Goddard Institute for Space Studies
The Goddard Institute for Space Studies (GISS) is a laboratory in the Earth Sciences Division of NASA's Goddard Space Flight Center affiliated with the Columbia University Earth Institute.
The institute is located at Columbia University in N ...
in 1967.
Career
After
graduate school
Postgraduate or graduate education refers to academic or professional degrees, certificates, diplomas, or other qualifications pursued by post-secondary students who have earned an undergraduate ( bachelor's) degree.
The organization and stru ...
, Hansen continued his work with
radiative transfer models, attempting to understand the
Venusian atmosphere
The atmosphere of Venus is the layer of gases surrounding Venus. It is composed primarily of Supercritical carbon dioxide, supercritical carbon dioxide and is much denser and hotter than atmosphere of Earth, that of Earth. The temperature at the ...
. He later applied and refined these models to understand the
Earth's atmosphere
The atmosphere of Earth is the layer of gases, known collectively as air, retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating pressure allowing fo ...
, and in particular, the effects that
aerosols and
trace gases have on Earth's climate. His development and use of
global climate model
A general circulation model (GCM) is a type of climate model. It employs a mathematical model of the general circulation of a planetary atmosphere or ocean. It uses the Navier–Stokes equations on a rotating sphere with thermodynamic terms ...
s has contributed to the further understanding of the
Earth's climate
Climate is the long-term weather pattern in an area, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteorological ...
. In 2009 his first book, ''
Storms of My Grandchildren'', was published. In 2012 he presented the
TED Talk
TED Conferences, LLC (Technology, Entertainment, Design) is an American-Canadian non-profit media organization that posts international talks online for free distribution under the slogan "ideas worth spreading". TED was founded by Richard Sau ...
"Why I must speak out about climate change".
From 1981 to 2013, he was the director of the
NASA
The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the US federal government responsible for the civil List of government space agencies, space program ...
Goddard Institute for Space Studies in
New York City
New York, often called New York City or NYC, is the most populous city in the United States. With a 2020 population of 8,804,190 distributed over , New York City is also the most densely populated major city in the Un ...
, a part of the
Goddard Space Flight Center.
, Hansen directs the Program on Climate Science, Awareness and Solutions at Columbia University's Earth Institute. 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 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.
Research and publications
As a college student at the
University of Iowa
The University of Iowa (UI, U of I, UIowa, or simply Iowa) is a public research university in Iowa City, Iowa, United States. Founded in 1847, it is the oldest and largest university in the state. The University of Iowa is organized into 12 col ...
, 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, his focus shifted to planetary research that involved trying to understand the climate change on earth that will result from
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
Remote sensing is the acquisition of information about an object or phenomenon without making physical contact with the object, in contrast to in situ or on-site observation. The term is applied especially to acquiring information about Eart ...
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
A general circulation model (GCM) is a type of climate model. It employs a mathematical model of the general circulation of a planetary atmosphere or ocean. It uses the Navier–Stokes equations on a rotating sphere with thermodynamic terms ...
s to help understand the observed climate trends, and diagnosing human impacts on climate.
Studies of Venus
![Venus-real color](https://upload.wikimedia.org/wikipedia/commons/e/e5/Venus-real_color.jpg)
In the late 1960s and early 1970s, following his Ph.D. dissertation, Hansen published several papers on the planet
Venus
Venus is the second planet from the Sun. It is sometimes called Earth's "sister" or "twin" planet as it is almost as large and has a similar composition. As an interior planet to Earth, Venus (like Mercury) appears in Earth's sky never f ...
. Venus has a high
brightness temperature
Brightness temperature or radiance temperature is the temperature at which a black body in thermal equilibrium with its surroundings would have to be in order to duplicate the observed intensity of a grey body object at a frequency \nu.
This con ...
in the radio frequencies compared to the infrared. He proposed that the hot surface was the result of aerosols trapping the internal energy of the planet.
More recent studies have suggested that several billion years ago,
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
A runaway greenhouse effect occurs when a planet's atmosphere contains greenhouse gas in an amount sufficient to block thermal radiation from leaving the planet, preventing the planet from cooling and from having liquid water on its surface. A ...
was caused by the evaporation of that original water, which generated a critical level of
greenhouse gases in its atmosphere.
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.
He also was able to use a
radiative transfer model
An atmospheric radiative transfer model, code, or simulator calculates radiative transfer of electromagnetic radiation through a planetary atmosphere.
Methods
At the core of a radiative transfer model lies the radiative transfer equation that ...
to establish an upper limit to the size of the ice particles if the clouds were actually made of ice.
Evidence published in the early 1980s showed that the clouds consist mainly of
sulfur dioxide and
sulfuric acid droplets.
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 were spherical and had a
refractive index
In optics, the refractive index (or refraction index) of an optical medium is a dimensionless number that gives the indication of the light bending ability of that medium.
The refractive index determines how much the path of light is bent, or ...
and
cloud drop effective radius
The cloud drop effective radius (alternatively cloud effective radius or simply effective radius when in context) is a weighted mean of the size distribution of cloud droplets. The term was defined in 1974 by James E. Hansen and Larry Travis as the ...
which eliminated all of the proposed cloud types except sulfuric acid.
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, confirming the same results obtained from transits across the sun.
The
Pioneer Venus project
The Pioneer Venus project was part of the Pioneer program consisting of two spacecraft, the Pioneer Venus Orbiter and the Pioneer Venus Multiprobe, launched to Venus in 1978. The program was managed by NASA's Ames Research Center.
The Pione ...
was launched in May 1978 and reached Venus late that same year. Hansen collaborated with
Larry Travis
Larry E. Travis (June 5, 1929 – August 14, 2017) was a Professor Emeritus at the Department of Computer Sciences as the University of Wisconsin–Madison. He had a faculty position at the University of Wisconsin as early as 1964 (two years befor ...
and other colleagues in a 1979 ''
Science
Science is a systematic endeavor that Scientific method, builds and organizes knowledge in the form of Testability, testable explanations and predictions about the universe.
Science may be as old as the human species, and some of the earli ...
'' article that reported on the development and variability of clouds in the ultraviolet spectrum. They concluded 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.
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.
Global temperature analysis
![Peoria ASOS](https://upload.wikimedia.org/wikipedia/commons/3/3c/Peoria_ASOS.jpg)
The first
NASA
The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the US federal government responsible for the civil List of government space agencies, space program ...
Goddard Institute for Space Studies (GISS) global temperature analysis was published in 1981. 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, providing a way to combine the station data to provide accurate long-term variations. They concluded 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 , with warming similar in both hemispheres.
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.
During a senate meeting on June 23, 1988, Hansen reported that he was ninety-nine percent certain the earth was warmer then than it had ever been measured to be, 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.
With the 1991 eruption of Mount Pinatubo, 1992 saw a cooling in global temperatures. There was speculation that this would cause the next couple of years to be cooler because of the large
serial correlation
Autocorrelation, sometimes known as serial correlation in the discrete time case, is the correlation of a signal with a delayed copy of itself as a function of delay. Informally, it is the similarity between observations of a random variable a ...
in the global temperatures. Bassett and Lin found the statistical odds of a new temperature record to be small.
Hansen countered by saying that having insider information shifted the odds to those who know the physics of the climate system, and that whether there is a new temperature record depends upon the particular data set used.
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 concluded that the recent
El Niño
El Niño (; ; ) is the warm phase of the El Niño–Southern Oscillation (ENSO) and is associated with a band of warm ocean water that develops in the central and east-central equatorial Pacific (approximately between the International Date ...
was not solely 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.
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 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.
The anomalously high global temperature in 1998 due to
El Niño
El Niño (; ; ) is the warm phase of the El Niño–Southern Oscillation (ENSO) and is associated with a band of warm ocean water that develops in the central and east-central equatorial Pacific (approximately between the International Date ...
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.
The temperature data was updated in 2006 to report that temperatures are now warmer than a century ago, and concluded that the recent global warming is a real climate change and not an artifact from the
urban heat island effect
An urban heat island (UHI) is an urban area, urban or metropolitan area that is significantly warmer than its surrounding rural areas due to human impact on the environment, human activities. The temperature difference is usually larger at nigh ...
. The regional variation of warming, with more warming in the higher latitudes, is further evidence of warming that is anthropogenic in origin.
In 2007,
Stephen McIntyre notified
GISS
The Goddard Institute for Space Studies (GISS) is a laboratory in the Earth Sciences Division of NASA's Goddard Space Flight Center affiliated with the Columbia University Earth Institute.
The institute is located at Columbia University in ...
that many of the U.S. temperature records from the
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. Hansen indicated that he felt that several news organizations had overreacted to this mistake.
In 2010, Hansen published a paper entitled "Global Surface Temperature Change" describing current global temperature analysis.
Black carbon studies
![Fire above Snake River](https://upload.wikimedia.org/wikipedia/commons/a/af/Fire_above_Snake_River.jpg)
Hansen has also contributed toward the understanding of
black carbon
Chemically, black carbon (BC) is a component of fine particulate matter (PM ≤ 2.5 µm in aerodynamic diameter). Black carbon consists of pure carbon in several linked forms. It is formed through the incomplete combustion of fossil fuel ...
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, through 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.
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.
This corresponds to an increase in the climate forcing of around , which they hypothesize is partially offset by the cooling of non-absorbing aerosols.
Estimations of trends in black carbon emissions show that there was a rapid increase in the 1880s after the start of the
Industrial Revolution
The Industrial Revolution was the transition to new manufacturing processes in Great Britain, continental Europe, and the United States, that occurred during the period from around 1760 to about 1820–1840. This transition included going f ...
, and a leveling off from 1900–1950 as environmental laws were enacted. China and India have recently increased their emissions of black carbon corresponding to their rapid development.
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.
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 than previously assumed.
Anthropogenic impact on climate
![Miamibeachnorth](https://upload.wikimedia.org/wikipedia/commons/8/87/Miamibeachnorth.jpg)
The
United Nations Framework Convention on Climate Change
The United Nations Framework Convention on Climate Change (UNFCCC) established an international environmental treaty to combat "dangerous human interference with the climate system", in part by stabilizing greenhouse gas concentrations in ...
is an international environmental treaty that has the objective of stabilizing greenhouse gas concentrations in the atmosphere at a level that would
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 () 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
A greenhouse gas (GHG or GhG) is a gas that absorbs and emits radiant energy within the thermal infrared range, causing the greenhouse effect. The primary greenhouse gases in Earth's atmosphere are water vapor (), carbon dioxide (), methane ...
other than carbon dioxide, such as
methane
Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Ea ...
and
chlorofluorocarbons
Chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) are fully or partly halogenated hydrocarbons that contain carbon (C), hydrogen (H), chlorine (Cl), and fluorine (F), produced as volatile derivatives of methane, ethane, and propa ...
. However, even then he wrote "the future balance of forcings is likely to shift toward dominance of CO
2 over aerosols".
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. He further stated that a lower limit on "dangerous anthropogenic interference" was set by the stability of the Greenland and Antarctic
ice sheet
In glaciology, an ice sheet, also known as a continental glacier, is a mass of glacial ice that covers surrounding terrain and is greater than . The only current ice sheets are in Antarctica and Greenland; during the Last Glacial Period at La ...
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 was not understood what 'dangerous' meant, or how humans were actually affecting climate. He described this as a
Faustian bargain
Faust is the protagonist of a classic German legend based on the historical Johann Georg Faust ( 1480–1540).
The erudite Faust is highly successful yet dissatisfied with his life, which leads him to make a pact with the Devil at a crossroad ...
because atmospheric aerosols had health risks, and should be reduced, but doing so would effectively increase the warming effects from .
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.
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 . The conclusion was that levels above 450
ppm were considered dangerous, but that reduction in non- greenhouse gases could provide temporary relief from drastic cuts. Further findings are that arctic climate change has been forced by non- constituents as much as by . The 2007 paper cautioned that prompt action is needed to slow growth and to prevent a dangerous anthropogenic interference.
Climate model development and projections
Vilhelm Bjerknes
Vilhelm Friman Koren Bjerknes ( , ; 14 March 1862 – 9 April 1951) was a Norwegian physicist and meteorologist who did much to found the modern practice of weather forecasting. He formulated the primitive equations that are still in use in num ...
began the modern development of the general circulation model in the early 20th century. The progress of numerical modeling was slow due to the slow speed of early computers and the lack of adequate observations. It wasn't until the 1950s that the numerical models were getting close to being realistic. 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.
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.
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.
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 could be run for five years. It was shown that global climate can be simulated reasonably well with a grid-point resolution as coarse as 1000 kilometers.
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.
The second generation of the GISS model was used to estimate the change in
mean surface temperature
The global temperature record shows the fluctuations of the temperature of the atmosphere and the oceans through various spans of time. There are numerous estimates of temperatures since the end of the Pleistocene glaciation, particularly dur ...
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 above the 1950–1980 mean for a few years, it would be the "smoking gun" pointing to human-caused global warming.
![James Hansen](https://upload.wikimedia.org/wikipedia/commons/8/85/James_Hansen.jpg)
In 2006, Hansen and colleagues compared the observations with the projections made by Hansen in his 1988 testimony before the
United States Congress
The United States Congress is the legislature of the federal government of the United States. It is bicameral, composed of a lower body, the House of Representatives, and an upper body, the Senate. It meets in the U.S. Capitol in Washing ...
. 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, with one in 1995, whereas the recent
Mount Pinatubo
Mount Pinatubo is an active stratovolcano in the Zambales Mountains, located on the tripoint boundary of the Philippine provinces of Zambales, Tarlac and Pampanga, all in Central Luzon on the northern island of Luzon. Its eruptive histor ...
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 were 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
Climate sensitivity is a measure of how much Earth's surface will cool or warm after a specified factor causes a change in its climate system, such as how much it will warm for a doubling in the atmospheric carbon dioxide () concentration. In te ...
used was higher than current estimates.
A year later, Hansen joined with
Rahmstorf and colleagues comparing climate projections with observations. The comparison was done from 1990 through January 2007 against physics-based models that are independent from the observations after 1990. They showed that the climate system may be responding faster than the models indicate. Rahmstorf and coauthors showed concern that
sea levels are rising at the high range of the IPCC projections, and that this was due to thermal expansion and not from melting of the
Greenland
Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland i ...
or
Antarctic ice sheets.
Following the launch of spacecraft capable of determining temperatures,
Roy Spencer and
John Christy published the first version of their
satellite temperature measurements
Satellite temperature measurements are inferences of the temperature of the atmosphere at various altitudes as well as sea and land surface temperatures obtained from radiometric measurements by satellites. These measurements can be used to lo ...
in 1990. Contrary to climate models and surface measurements, their results showed a cooling in the
troposphere
The troposphere is the first and lowest layer of the atmosphere of the Earth, and contains 75% of the total mass of the planetary atmosphere, 99% of the total mass of water vapour and aerosols, and is where most weather phenomena occur. From ...
.
However, in 1998, Wentz and Schabel determined that
orbital decay had an effect on the derived temperatures.
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
global warming denialists, and that the correction of the data would result in a change from discussing whether global warming is occurring to what is the rate of global warming, and what should be done about it.
Hansen has continued the development and diagnostics of climate models. For instance, he has helped in the investigations of the decadal trends in
tropopause
The tropopause is the atmospheric boundary that demarcates the troposphere from the stratosphere; which are two of the five layers of the atmosphere of Earth. The tropopause is a thermodynamic gradient-stratification layer, that marks the end of ...
height, which could be a useful tool for determining the human "fingerprint" on climate.
, 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
Marine stratocumulus is a type of stratocumulus cloud that form in the stable air off the west coast of major land masses. The Earth spins on its axis, which results in the Coriolis force pushing the ocean surface water away from the coast in the ...
clouds.
A later paper showed that the model's main problems are having too weak of an
ENSO-like variability, and poor sea ice modeling, resulting in too little ice in the
Southern Hemisphere and too much in the
Northern Hemisphere.
Climate forcings, feedbacks, and sensitivity
![NasaHansenFig1](https://upload.wikimedia.org/wikipedia/commons/9/96/NasaHansenFig1.gif)
In 2000 Hansen authored a paper called "Global warming in the twenty-first century: an alternative scenario" in which he presented a more optimistic way of dealing with global warming, focusing on non-CO
2 gases and
black carbon
Chemically, black carbon (BC) is a component of fine particulate matter (PM ≤ 2.5 µm in aerodynamic diameter). Black carbon consists of pure carbon in several linked forms. It is formed through the incomplete combustion of fossil fuel ...
in the short run, giving more time to make reductions in
fossil fuel emissions. He notes that the net warming observed to date is roughly as big as that expected from non-CO
2 gases only. This is because CO
2 warming is offset by climate-cooling aerosols emitted with fossil fuel burning and because at that time non-CO
2 gases, taken together, were responsible for roughly 50% of the anthropogenic greenhouse gas warming.
In a 2007 paper, Hansen discussed the potential danger of "fast-feedback" effects causing
ice sheet
In glaciology, an ice sheet, also known as a continental glacier, is a mass of glacial ice that covers surrounding terrain and is greater than . The only current ice sheets are in Antarctica and Greenland; during the Last Glacial Period at La ...
disintegration, based on
paleoclimate data.
George Monbiot
George Joshua Richard Monbiot ( ; born 27 January 1963) is a British writer known for his environmental and political activism. He writes a regular column for ''The Guardian'' and is the author of a number of books.
Monbiot grew up in Oxfordsh ...
reports "The
IPCC
The Intergovernmental Panel on Climate Change (IPCC) is an intergovernmental body of the United Nations. Its job is to advance scientific knowledge about climate change caused by human activities. The World Meteorological Organization (WMO) ...
predicts that sea levels could rise by as much as this century. Hansen's paper argues that the slow melting of ice sheets the panel expects doesn'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 2–3°C (3.6–5.4°F) above today's level 3.5 million years ago, sea levels rose not by 59 centimeters but by . The ice responded immediately to changes in temperature."
Hansen stressed 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."
He concludes that "present knowledge does not permit accurate specification of the dangerous level of human-made
reenhouse 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."
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)°C based on
Pleistocene
The Pleistocene ( , often referred to as the ''Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed in ...
paleoclimate data. The paper also concluded that burning all fossil fuels "would make most of the planet uninhabitable by humans."
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
The Atlantic meridional overturning circulation (AMOC) is part of a global thermohaline circulation in the oceans and is the zonally integrated component of surface and deep currents in the Atlantic Ocean. It is characterized by a northward fl ...
(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.
Analysis of climate change causation
Hansen noted that in determining responsibility for climate change, the effect of greenhouse gas emissions on climate is 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
People's Republic of China
China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...
.
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
The Competitive Enterprise Institute (CEI) is a non-profit libertarian think tank founded by the political writer Fred L. Smith Jr. on March 9, 1984, in Washington, D.C., to advance principles of limited government, free enterprise, and individ ...
's commercials with the tagline "carbon dioxide—they call it pollution, we call it life", and politicians who accept money from fossil-fuel interests and then describe global warming as "a great hoax." 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. He was a critic of both the
Clinton and
George W. Bush Administration
George W. Bush's tenure as the 43rd president of the United States began with his first inauguration on January 20, 2001, and ended on January 20, 2009. Bush, a Republican from Texas, took office following a narrow victory over Democratic ...
s' stances on climate change.
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."
Climate change activism
US Senate committee testimony
Hansen was invited by
Rafe Pomerance
Rafe Pomerance (born July 19, 1946) is an American environmentalist. He is Chairman of Arctic 21, a network of organizations focused on communicating issues of Arctic climate change to policy-makers and the general public. Beginning in the late ...
to testify before the
United States Senate Committee on Energy and Natural Resources
The United States Senate Committee on Energy and Natural Resources is a standing committee of the United States Senate. It has jurisdiction over matters related to energy and mineral resources, including nuclear development; irrigation and recl ...
on June 23, 1988.
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"
[ 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."] 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.[
According to science historian ]Spencer R. Weart
Spencer R. Weart (born 1942) is the former director of the Center for History of Physics of the American Institute of Physics (AIP) from 1971 until his retirement in 2009.
Life
Originally trained as a physicist, he is now a historian of scienc ...
, Hansen's testimony increased public awareness of climate change. According to Richard Besel of California Polytechnic State University, Hansen's testimony "was an important turning point in the history of global climate change."[ According to Timothy M. O'Donnell of the ]University of Mary Washington
The University of Mary Washington (UMW) is a public liberal arts university in Fredericksburg, Virginia. Founded in 1908 as the Fredericksburg Teachers College, the institution was named Mary Washington College in 1938 after Mary Ball Washi ...
, 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." According to Roger A. Pielke of the National Center for Atmospheric Research
The US National Center for Atmospheric Research (NCAR ) is a US federally funded research and development center (FFRDC) managed by the nonprofit University Corporation for Atmospheric Research (UCAR) and funded by the National Science Foundatio ...
, 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."
Criticism of coal industry
Hansen has been particularly critical of the coal industry
Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen.
Coal is formed when de ...
, stating that coal contributes the largest percentage of anthropogenic carbon dioxide into the atmosphere. 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
Russia (, , ), or the Russian Federation, is a transcontinental country spanning Eastern Europe and Northern Asia. It is the largest country in the world, with its internationally recognised territory covering , and encompassing one-eig ...
and Saudi Arabia
Saudi Arabia, officially the Kingdom of Saudi Arabia (KSA), is a country in Western Asia. It covers the bulk of the Arabian Peninsula, and has a land area of about , making it the fifth-largest country in Asia, the second-largest in the A ...
, and that no matter how fuel-efficient automobiles become, the oil will eventually be burned and the emitted. In a 2007 testimony before the Iowa Utilities Board The Iowa Utilities Board (IUB) is a 3-member public utilities commission, with beginnings in 1878. It is a quasi-judicial tribunal, which regulates services and rates of electric, natural gas, water and telecommunication providers in the U.S. state ...
, 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. He has called for phasing out coal power completely by the year 2030.
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." In response, the National Mining Association
The National Mining Association (NMA) is a United States trade organization that lists itself as the voice of the mining industry in Washington, D.C. NMA was formed in 1995, and has more than 300 corporate members.
History
The National Mining As ...
stated that his comparison "trivialized the suffering of millions" and "undermined his credibility." 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
The Holocaust, also known as the Shoah, was the genocide of European Jews during World War II. Between 1941 and 1945, Nazi Germany and its collaborators systematically murdered some six million Jews across German-occupied Europe; ...
and then apologized, saying he regretted that his words caused pain to some readers.
Mountaintop removal mining
On June 23, 2009, James Hansen, along with 30 other protester
A protest (also called a demonstration, remonstration or remonstrance) is a public expression of objection, disapproval or dissent towards an idea or action, typically a political one.
Protests can be thought of as acts of cooper ...
s including actress Daryl Hannah
Daryl Christine Hannah (born December 3, 1960) is an American actress and environmental activist. She made her screen debut in Brian De Palma's supernatural horror film '' The Fury'' (1978). She has starred in various movies across the years, i ...
, was arrested on misdemeanor charges of obstructing police and impeding traffic, during a protest against mountaintop removal mining
Mountaintop removal mining (MTR), also known as mountaintop mining (MTM), is a form of surface mining at the summit or summit ridge of a mountain. Coal seams are extracted from a mountain by removing the land, or overburden, above the seams. Thi ...
in Raleigh County, West Virginia. The protesters intended to enter the property of Massey Energy Company, but were blocked by a crowd of several hundred coal miners and supporters. Hansen said that mountaintop removal for coal mining " rovidesonly a small fraction of our energy" and "should be abolished." Hansen called on President Barack Obama
Barack Hussein Obama II ( ; born August 4, 1961) is an American politician who served as the 44th president of the United States from 2009 to 2017. A member of the Democratic Party, Obama was the first African-American president of the ...
to abolish mountaintop coal mining.
Hansen and about 100 other people were arrested in September 2010 in front of the White House
The White House is the official residence and workplace of the president of the United States. It is located at 1600 Pennsylvania Avenue NW in Washington, D.C., and has been the residence of every U.S. president since John Adams in ...
in Washington, DC. The group was seeking a ban on mountaintop removal or surface mining.
Cap and trade
In 2009 Hansen spoke out against cap and trade
Emissions trading is a market-based approach to controlling pollution by providing economic incentives for reducing the emissions of pollutants. The concept is also known as cap and trade (CAT) or emissions trading scheme (ETS). Carbon emission t ...
, advocating instead what he believes would be a progressive carbon tax
A carbon tax is a tax levied on the carbon emissions required to produce goods and services. Carbon taxes are intended to make visible the "hidden" social costs of carbon emissions, which are otherwise felt only in indirect ways like more sev ...
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.[James Hansen. Tell Barack Obama the Truth – The Whole Truth. accessed December 10, 2009.]
Retirement from NASA
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
A greenhouse gas (GHG or GhG) is a gas that absorbs and emits radiant energy within the thermal infrared range, causing the greenhouse effect. The primary greenhouse gases in Earth's atmosphere are water vapor (), carbon dioxide (), methane ...
. 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.
Keystone Pipeline
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, 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." 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. 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.
Proposed solutions
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."
At the end of 2008, James 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."
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 CO2". 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".
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.
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". Kharecha and Hansen countered that all the data these scientists use to make their criticism, "lacks credibility".
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." 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.
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.
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." In 2001, he received the 7th Annual Heinz Award in the Environment (endowed with US$250,000) for his research on global warming, 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 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."
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."
In 2009, Hansen was awarded the 2009 Carl-Gustaf Rossby Research Medal, 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."
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'', 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".
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
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.
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 . The scores of models currently in use to chart climate evolution are heirs to those developed by Manabe and Hansen.
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.
Controversies
Political interference at NASA
In 2006, Hansen alleged that NASA
The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the US federal government responsible for the civil List of government space agencies, space program ...
administrators had attempted to influence his public statements about the Attribution of recent climate change, causes of climate change. 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. 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".
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. 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.
Trials for energy company executives
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 common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...
, in the same way that tobacco companies tried to hide the link between smoking and cancer.
Arrest for protest demonstration
Hansen and 1,251 other activists were arrested in August and September 2011, at another demonstration 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. 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.
Criticism
Around 2009, Hansen received several criticisms, largely focussing on his climate activism. It is notable, however, that the decade since these criticisms were published was the hottest on record.
In January 2009, Andrew Freedman wrote in ''The Washington Post'', that the American Meteorological Society had erred in giving Hansen its Carl-Gustaf Rossby Research 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." Former AMS member Joseph D'Aleo, a skeptic of human-caused climate change, also criticized the award.
Also in 2009, physicist Freeman Dyson criticised 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." Hansen responded that if Dyson "is going to wander into something with major consequences for humanity and other life on the planet, then he should first do his homework". Dyson stated in an interview that the argument with Hansen was exaggerated by ''The New York Times'', stating that he and Hansen are "friends, but we don't agree on everything."
After Hansen's arrest in 2009 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."
In June 2009, ''The New Yorker, New Yorker'' journalist Elizabeth Kolbert wrote that Hansen is "increasingly isolated among climate activists." 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."
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." "The right wing loves what he's doing," said Joseph Romm, a senior fellow at the Center for American Progress, a liberal think tank. 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.
Publications
Over 160 publications have been authored by James Hansen. Since 2020, he has published observations and commentary a
redgreenandblue.org
averaging approximately once per month.
*
See also
References
Further reading
*
External links
*
Program on Climate Science, Awareness and Solutions
at the Earth Institute, Columbia University
James Hansen's page
at the Department of Earth and Environmental Sciences, Columbia University
at the Goddard Institute for Space Studies
*
James Hansen
on C-SPAN
''James Hansen - Scientific Reticence: A Threat to Humanity and Nature''
Press Conference in Bonn during COP23, 2017-11-19 (24 min). Fro
''ClimateMatters.TV''
series o
United Planet Faith and Science Initiative
*
{{DEFAULTSORT:Hansen, James
1941 births
Living people
American climatologists
21st-century American physicists
Atmospheric physicists
Carl-Gustaf Rossby Research Medal recipients
Goddard Space Flight Center people
Members of the United States National Academy of Sciences
NASA people
People from Denison, Iowa
Science activists
Sustainability advocates
University of Iowa alumni
Sierra Club awardees