December 9, 2011

James Hansen

Green Army: Persons of Interest

Chuck Kutscher [National Renewable Energy Laboratory]:
If you want to know the scientific consensus on global warming, read the reports by the Intergovernmental Panel on Climate Change.
But if you want to know what the consensus will be ten years from now, read Jim Hansen's work.

Protecting the Home Planet

[Nature] and the laws of physics cannot compromise — they are what they are.
(p xi)

[On] June 23, 1988 … I testified to a Senate committee [that,] with 99% confidence [the] Earth was being affected by human-made greenhouse gases, and the planet had entered a period of long-term warming.
(p xv)

"Clean coal" is an oxymoron.
The clean-coal concept, at least so far, has been … a diversion that the coal industry and its government supporters employ to allow dirty-coal uses to continue. …
[To prevent dangerous anthropogenic interference with the climate system, coal] use must be prohibited unless and until the emissions can be captured and safely disposed of.
(p 174)

Now, what are the means by which fossil fuel use can be reduced and eventually phased out? The first priority … must go to energy efficiency. …
People in the United States, Canada, and Australia use about twice as much energy per capita as those in Europe or Japan …
California achieves energy efficiency close to that of Europe and Japan.
Since 1975, per capita use of electricity in California has remained constant, while growing 50% in the rest of the United States. …
(p 190)

Utility regulations in California also are structured such that the utilities make more money by encouraging efficiency rather than by selling more energy.

The second priority … is renewable energies …
(p 191)

However … renewable energies will not be a sufficient source of [baseload] electric power [in the forseeable future.]
[Currently,] there are now just two options for nearly carbon-free large-scale baseload electric power: (p 193)

[It would cost trillions] of dollars for new carbon-capturing power plants to replace all the old ones in China and India that emit carbon dioxide to the atmosphere.
(p 194)

The World Health Organization calculates that there might be as many as four thousand [excess] cancer deaths because of radiation released at Chernobyl, which compares with one hundred thousand other cancer deaths among the same population. …
[A conservative estimate of deaths attributable to coal related air pollution is] ten thousand deaths per year — every year.
(p 195-6)

[The] backbone of a solution to the climate problem is a flat carbon emissions price applied across all fossil fuels at the source.
This carbon price (fee, tax) must rise continually, at a rate that is economically sound.
The funds must be distributed back to the citizens (not to special interests) — otherwise the tax rate will never be high enough to lead to a clean energy future.
(p 219)

Climate history is our best source of information about how sensitive the climate system is, and, it turns out, the climate is remarkably sensitive — large climate changes can occur in response to even small forcings.
(p 35)

[Humans,] by burning fossil fuels, are now increasing atmospheric carbon dioxide by 2 ppm per year.
[This human induced] climate forcing is [twenty thousand times] more powerful than the natural forcing [ie one ten thousandth of 1 ppm per year due to tectonic activity.]
(p 161)

The carbon dioxide amount 34 million years ago, when Antarctica became cold enough to harbor a large ice sheet, was found to be 450 [350-550] ppm …

If humanity burns most of the fossil fuels, doubling or tripling the preindustrial carbon dioxide level, Earth will surely head toward the ice-free condition …
It is difficult to say how long it will take for the melting to be complete, but once ice sheet disintegration gets well under way, it will be impossible to stop.
(p 160, emphasis added)

[The] last time that Earth was 2 or 3 degrees warmer than today [ie] about three million years ago, [sea] level was about 25 meters (80 feet) higher than today. …
About a billion people now live at elevations less than 25 meters. …
A sea level rise of [even] 5 meters (about 17 feet) would submerge most of Florida, Bangladesh, the European lowlands …
(p 141-2)

The rate of sea level rise can be rapid once ice sheets begin to disintegrate.
About 14,000 years ago, sea level increased 4 to 5 meters per century for several consecutive centuries — an average rate of 1 meter every 20 or 25 years.
(p 38)

If ice sheets begin to disintegrate, there will not be a new stable sea level on any foreseeable time scale.
Instead, we will have created a situation with continual change, with intermittent calamities at thousands of cities around the world. …
Change will not be smooth and uniform.
Instead, local catastrophes will occur in association with regional storms.
Given the enormous infrastructure and historical treasures in our coastal cities, it borders on insanity to suggest that humans should [rely on adaptation to, as opposed to mitigation of, climate change.]

Would coastal cities be rebuilt, given the knowledge that sea level will continue to rise? …
[Where] would people in low-lying regions such as Bangladesh migrate to?
Global chaos will be difficult to avoid if we allow the ice sheets to become unstable.
(p 85)

[Most] of the climate response to fossil fuel emissions will occur … within the lifetimes of our children and grandchildren. …
[If] we burn all [known conventional] reserves of oil, gas, and coal, there is a substantial chance we will initiate [a] runaway greenhouse [effect and] destroy all life on the planet …
If we also burn the tar sands and tar shale … the Venus syndrome is a dead certainty.
(p 236, emphasis added)

The [safe] limit on permitted global warming, if we wish to preserve the great ice sheets on Antarctica and Greenland, and thus preserve the coastlines that have existed for the past seven thousand years, is much less than has generally been assumed [ie 350 ppm of carbon dioxide.]
Halting global warming is still feasible — but requires international cooperation in taking urgent, unprecedented actions, which would have additional benefits for human health, agriculture, and the environment.
(p 34)

[In 1863] Abraham Lincoln … established the National Academy of Sciences {to advise the nation on important matters that required the best scientific expertise}.
President Bush, early in his first term, asked the academy for advice on global warming.
Specifically, the White House sought the academy's evaluation of the conclusions reached by the Intergovernmental Panel on Climate Change [which had been making] increasingly strong statements about the likely consequences of continued increases of greenhouse gases.
The White House was probably hoping that the academy would document some criticisms of the [IPCC's conclusions.]
If so, the White House was disappointed.
(p 56)

The answer that the National Academy of Sciences had delivered … was not the answer the White House wanted to hear.
The president did not ask the academy for advice about global warming again during the remainder of his eight years in power.
(p 58)

Coal burning at power plants is the greatest source of increasing atmospheric carbon dioxide.
It is also the source most susceptible to control.
[Bush's decision in March 2001] not to restrict power plant emissions reneged on a promise [he] made repeatedly during the 2000 presidential election campaign … to include carbon dioxide in a "four pollutant strategy" to reduce the most damaging pollutants from power plants.
That promise, together with the Clinton-Gore administration's poor record in constraining carbon dioxide emissions, stymied Al Gore from raising the environment and climate change as an effective campaign issue.
Given the razor-thin margin in the 2000 election, and the environmental awareness of Florida voters, it seems clear that Gore would have become president if it were not for Bush's pollution-reduction promise.
(p 2)

[On the other hand, the Bush administration did take steps to reduce] non-carbon dioxide emissions, including methane and black soot. …
[The methane-to-markets program] helps reduce methane emissions via capture at coal mines, landfills, and agricultural and waste management facilities and uses the captured methane as fuel.
White House interest helped Kruger and the EPA initiate the program in the United States and extend its effectiveness via cooperation with several developing countries that have larger methane emissions than the United States.
This approach, extended globally, is better than the Kyoto Protocol approach [since methane] is one of the escape hatches that make the Kyoto approach ineffectual for carbon dioxide.
The Bush administration also deserves credit for major tightening of soot emission limits in the face of opposition from diesel producers, truckers, and other industries.
In addition to supporting rules that reduced soot emissions from trucks and buses, the administration later expanded regulations to cover tractors, trains, and ships.
(p 52, emphasis added)

In my talks I began to emphasize the first line of the NASA mission statement:
[To] understand and protect our home planet.
But in the spring of 2006, a NASA colleague sent me an e-mail warning me that I had better stop using that statement as a rationalization for my actions because it no longer existed.
Sure enough, when I checked the mission statement on the NASA Web site, the phrase "to understand and protect our home planet" was gone.
[Nobody] knew what had happened.
It had just disappeared.
The second thing to disappear was 20% of the NASA earth science research and analysis budget.
Because most of the budget goes toward fixed items, such as rent and civil service salaries, a 20% cut is monstrous, a signal almost of going out of business.
(p 135)
Mark Bowen:
A high insider at headquarters told me that Michael Griffin rewrote the mission statement and the agency's strategic plan basically on his own.
(Censoring Science, Dutton, 2008)
(p 136)
Michael Griffin [NASA Administrator]:
[Climate change is only a problem if you] assume that the state of the Earth's climate today is the optimal climate, the best climate that we could have or ever have had, and that we need to take steps to make sure that it doesn't change.
First of all, I don't think it's within the power of human beings to assure that the climate does not change, as millions of years of history have shown.
And second of all, … I would ask which human beings … are to be accorded the privilege of deciding that this particular climate that we have … right now, is the best climate for all other human beings.
I think that's a rather arrogant position for people to take.
(p 152)

David Mould, [George W Bush appointee and] head of public affairs for NASA, [had] held senior positions in public and media relations at the Southern Company of Atlanta, the second-largest holding company of coal-burning utilities in the United States and thus the second greatest emitter of carbon dioxide.
Southern's contributions to the Republican Party [in 2000] were exceeded … only by Enron's.
(p 127)

Would you like to know more?

Tell Barack Obama The Truth

Coal waste [has] caused far more environmental damage and human injury than has the waste from all the nuclear power plants in the world [including Chernobyl.]
Mercury released in coal burning contaminates the world ocean as well as our rivers, lakes and soil.
Air pollution from coal burning kills more than 100,000 people per year. …

Open Letter to Michelle and Barack Obama

  • Switzerland finances construction of coal plants,
  • Sweden builds them, and
  • Australia exports coal and sets atmospheric carbon dioxide goals so large as to guarantee destruction of much of the life on the planet.


Protecting the Home Planet


4th Generation Nuclear Power


Director, Program on Climate Science, Awareness and Solutions, Earth Institute, Columbia University.
Director, NASA Goddard lnstitute for Space Studies (GISS) (1981-2013).

  • The storms of James Hansen, Late Night Live, ABC Radio National, 8 July 2010.

    [John Mercer] was the scientist who had warned that the West Antarctic Ice Sheet might be unstable if we have ocean warming and it begins to melt the ice shelves that buttress the ice sheet …
    [He] promptly lost his funding. …
    [The] people who speak out do not get rewarded.

  • Storms Of My Grandchildren, Bloomsbury, 2009.

    Richard Lindzen, of the Massachusetts Institute of Technology … is the dean of global warming contrarians [and] the one who … has the most impressive scholarly credentials.
    He was elected to the National Academy of Sciences at a tender age, primarily as a result of a brilliant mathematical analyses of atmospheric dynamics.
    (p 11)

    He and other contrarians tend to act like lawyers defending a [client:] presenting only arguments that favor their client. …
    The scientific method [(which takes a more equivocal approach to evidence) is, in one sense,] a handicap in a debate before a nonscientist audience. …
    The difference between scientist-style and lawyer-style tends to favor the contrarian in a discussion before an audience that is not expert in the science. …
    (p 12)

    A lawyer does not seek truth; a lawyer seeks a win for a client.
    That approach makes it difficult for the public.
    Lindzen makes qualitative statements that sound reasonable, and he raises technical matters that a layperson cannot assess, making it sound like there is an argument among theorists.
    (p 56)

    [Furthermore, contrarians keep] changing their arguments as the real-world evidence for global warming continued to strengthen, conveniently forgetting prior statements that were proven wrong. …
    (p 12)

    [For example, Lindzen has previously repeatedly asserted] that global warming over the prior century was only about 0.1 degree Celsius.
    [In fact, by] the late 1980s that global warming was about 0.6 degree Celsius … and subsequent additional warming [has] increased total global warming to almost 0.8 degree Celsius.
    (p 14)

    A draw in a global warming "debate" is a loss, because policy inaction is the aim of those who dispute global warming.

    … US policies regarding carbon dioxide during the Bush-Cheney administration seem to have been based on, or at minimum, congruent with, Lindzen's perspective [— which he has summarized as follows:]
    (p 53, emphasis added)

    1. Scientists who are willing to speak out in support of hysteria are supported with funding, awards, and even legal assistance.
    2. The environmental movement coordinates public pronouncements so as to guarantee that all spokesmen are "on the same page."
    3. Institutions, dependent on support, are supportive of alarmism.
    4. Scientists who protest alarmism are out in the cold.
      There is no assistance from any direction. …

    There are reasons to believe that Bush, Cheney, and Rove all shared Lindzen's [distrust of] the scientific community.
    (pp 57-8)

    [In] 1981 I had lost funding for research on the climate effects of carbon dioxide because the Energy Department was displeased with a paper, "Climate Impact of Increasing Atmospheric Carbon Dioxide," I had published in Science magazine.
    The paper made a number of predictions for the twenty-first century, including "opening of the tabled Northwest Passage," which the Energy Department considered to be alarmist but which have since proven to be accurate. …

    [Lindzen] had been a witness for tobacco companies decades earlier, questioning the reliability of statistical connections between smoking and health problems [in a way] closely analogous to his views of climate data.
    (p 15)

    [The] final descent into full ice age conditions 70,000 years ago was rapid and coincided with the one near extinction of humans …
    [As] few as one thousand breeding pairs are estimated to have survived during the population bottleneck.
    A popular theory for the cause of both this rapid cooling and population decline is the colossal eruption of the Toba supervolcano at about that time.
    Geologic records indicate that Toba ejected at least eight hundred cubic kilometers of material, compared with four cubic kilometers from the 1991 Pinatubo eruption, the largest volcanic eruption of the past century. …
    (p 39)

    [During the most recent ice age,] twenty thousand years ago, most of Canada was under a huge ice sheet, as much as three kilometers (two miles) thick.
    That ice sheet pushed south, over the US border, covering the areas of Seattle, Minneapolis, and New York.
    (p 36)

    [The] sea level was 110 meters (about 350 feet) lower than it is today, exposing much of the present continental shelves.
    (p 38)

    The huge sea level changes [during that period] played an important role in the development of human societies. …
    [Indeed, sea level stabilization may have been a the precondition for] the development of complex human societies.
    The social hierarchies of complex societies require food yields sufficient to support the non-food-producing component.
    [Almost] all of the first known population centers, on several continents, date to about 6,000 to 7,000 years ago [— a time] when the rate of sea level rise slowed markedly.
    Until then … sea level had increased … at an average rate of more than one meter per century for several thousand years.
    (p 39)

    The Holocene's stable sea level [during the period in which human civilisation has developed] may be related to the fact that temperature peaked early in the Holocene [following by] a slight cooling trend.
    (p 142)

    Most human settlements were either coastal or riverine, often in delta regions.
    Coastal biologic productivity and fish populations are low while sea level is changing, but they can increase an order of magnitude with stable sea level.
    Thus it has been hypothesized that the [grain and] high-protein fish diets that become possible with stable sea level account for the near-simultaneous development of complex societies worldwide. …
    [However, this 7,000 year] period of near-stable sea level is [now coming to an] end.
    (p 40)

    Sea level is now rising [at an accelerating rate.]
    [Currently, at] more than three centimeters per decade — double the rate that occurred in the twentieth century.
    (p 50)

    Global average temperature was 5 degrees Celsius warmer in the Holocene than in the last ice age …
    [The combined difference in radiative forcing (GHG and surface changes)] of about 6.5 watts [implies] a climate sensitivity of about 0.75 degree Celsius for each watt of forcing.
    This corresponds to 3 degrees Celsius for the 4-watt forcing [associated with a doubling of carbon dioxide levels.]
    (p 45-6)

    The natural [orbital] forcing due to [changes in incident solar radiation,] averaged over the planet, is a small fraction of 1 watt. …
    [This small solar forcing is amplified by] surface albedo and carbon dioxide feedbacks [to 6.5 watts causing the observed 5 degree Celsius fall in global average temperatures and ice age conditions. …]

    Both global surface albedo and greenhouse gas amount are now under human control.
    (p 49)

    The ultimate forcing due to the 1750-2000 C02 increase is about 1.5 watts.
    Other human-caused changes, such as adding methane, nitrous oxide, chlorofiuorocarbons (CFCs), and ozone to the atmosphere, make the total greenhouse gas forcing about 3 watts. …
    [The] net climate forcing in 2000 relative to the preindustrial climate was between 1.5 and 2 watts …
    [Net climate forcing as of 2011 was 2.29 watts.]
    (p 9)

    Global warming of 2 degrees Celsius or more would make Earth as warm as it had been in the Pliocene, three million years ago.
    Pliocene warmth caused sea levels to be about twenty-five meters (eighty feet) higher than they are today.
    (p 13)

    Florida was under water.
    About a billion people now live at elevations less than 25 meters.
    (p 141)

    … Climate change in response to human-made forcing will be much more rapid than … natural changes.
    The speed of glacial-interglacial change is dictated by 20,000-, 40,000-, and 100,000-year time scales for changes of Earth's orbit — but this does not mean that the climate system is inherently that lethargic.
    On the contrary.
    Human-made climate forcing, by paleoclimate standards, is large and changes in decades, not tens of thousands of years.
    (p 71, emphasis added)

    Studies of more than one thousand species of plants, animals, and insects … found an average migration rate toward the north and south poles of about four miles per decade in the second half of the twentieth century.
    That is not fast enough.
    During the past thirty years the lines marking the regions in which a given average temperature prevails ("isotherms") have been moving poleward at a rate of about thirty-five miles per decade. …
    [The] movement is inexorably toward the poles and totals more than one hundred miles over the past several decades.
    If greenhouse gases continue to increase at business-as-usual rates, then the rate of isotherm movement will double in this century to at least seventy miles per decade. …
    Polar animals [and Alpine species will,] in effect, will be pushed off the planet.
    (p 146)

    We do not know how many animal, plant, insect, and microbe species exist today. …
    Bird species are documented better than most. …
    In total, about 1% of bird species have disappeared over the past several centuries.
    If the loss of birds is representative of other species, several thousand species are becoming extinct each year.
    The current extinction rate is at least one hundred times greater than the average natural rate.
    (p 147)

    The largest volume of methane hydrates is on continental shelves, in the top several hundred meters of ocean sediments, although a smaller volume exists in continental tundra. …
    If a warming occurs that is large enough to melt methane hydrate, each liter of melted hydrate expands into 160 liters of methane gas.
    (p 162)

    Methane is a strong greenhouse gas, and on a time scale of about a decade it is oxidized to carbon dioxide, which will continue to cause warming for centuries. …
    [Methane] hydrate models that are consistent with the limited data suggest a total inventory of about 5,000 gigatons of carbon …
    (p 163)

    [The] Paleocene-Eocene thermal maximum [was a] rapid warming of at least 5 degrees Celsius that occurred about 55 million years ago and caused a minor rash of extinctions, mainly of marine species.
    (p 161)

    [Most of the warming is likely to have been instigated by] the melting of methane hydrates [triggered by changes in ocean circulation.]
    Why ocean circulation changed is uncertain, but it is likely related to the global warming of 2 to 3 degrees Celsius that occurred just prior to the PETM event.
    The recovery time from … the PETM global warming spike, was about 100,000 years.
    (p 162)

    [The] Gravity Recovery and Climate Experiment (GRACE) reveal that the Greenland ice sheet has been losing mass for the past few years at a rate of about 100 cubic kilometers per year.
    West Antarctica is losing mass at a comparable, although somewhat smaller rate.
    (p 255)

  • 4th Generation Nuclear Power, OSS Foundation, 18 January 2009.

    Fourth generation nuclear power has the potential to provide safe base-load electric power with negligible CO2 emissions. …

    [Fast] reactors can completely burn the uranium.
    Moreover, they can burn existing long-lived nuclear waste, producing a small volume of waste with half-life of only several decades, thus largely solving the nuclear waste problem.

    The other compelling alternative is to use thorium as the fuel in thermal reactors.
    Thorium can be used in ways that practically eliminate build-up of long-lived nuclear waste. …

    The Integral Fast Reactor (IFR) concept was developed at the Argonne National Laboratory and it has been built and tested at the Idaho National Laboratory. …

    The Liquid-Fluoride Thorium Reactor (LFTR) is a thorium reactor concept that uses a chemically-stable fluoride salt for the medium in which nuclear reactions take place. …
    LFTR also has the potential to destroy existing nuclear waste, albeit with less efficiency than in a fast reactor such as IFR.

    Both IFR and LFTR) operate at low pressure and high temperatures, unlike today’s [Light Water Reactors (LWRs).]
    Operation at low pressures alleviates much of the accident risk with LWR.
    Higher temperatures enable more of the reactor heat to be converted to electricity (40% in IFR, 50% in LFTR vs 35% in LWR).
    Both IFR and LFTR have the potential to be air-cooled and to use waste heat for desalinating water.

    Both IFR and LFTR are 100-300 times more fuel efficient than LWRs.
    In addition to solving the nuclear waste problem, they can operate for several centuries using only uranium and thorium that has already been mined. …

    Coal burning has released and spread around the world more than 100 times more radioactive material than all the nuclear power plants in the world.
    Mercury released in coal burning contaminates the world ocean as well as our rivers, lakes and soil.
    Air pollution from coal burning kills more than 100,000 people per year. …
    Mining of coal, especially mountaintop removal, causes additional environmental damage and human suffering. …

    The common presumption that 4th generation nuclear power will not be ready until 2030 is based on assumption of "business-as-usual".
    Given high priority, this technology could be ready for deployment in the 2015-2020 time frame, thus contributing to the phase-out of coal plants. …

  • Dear Michelle and Barack, 29 December 2008.
  • Tell Barack Obama the Truth, 29 December 2008.

    Principal implications

    CO2 is not the only human-made gas that contributes to global warming …
    [But since it] remains in the air [for] more than 1000 years [it] must be the focus of efforts to stop human-caused climate change. …
    (p 2)

    [If] construction of new coal plants continues for even another decade it is difficult to conceive of a practical, natural way to return CO2 below 350 ppm.
    (p 3)

    Outline of policy options

    Many energy experts consider an all-renewable scenario to be implausible in the time-frame when coal emissions must be phased out …
    [It] would be dangerous to proceed under the presumption that we will soon have all-renewable electric power. …

    No commitment for large-scale deployment of either 4th generation nuclear power or carbon capture is needed at this time.
    If energy efficiency and renewable energies prove sufficient for energy needs, some countries may choose to use neither nuclear power nor coal.
    However, we must be certain that proven options for complete phase-out of coal emissions are available.
    (p 4)

    Tax and 100% dividend

    A “carbon tax with 100% dividend” is needed to reverse the growth of atmospheric CO2. …

    The entire tax should be returned to the public, equal shares on a per capita basis (half shares for children up to a maximum of two child-shares per family), deposited monthly in bank accounts.
    No bureaucracy is needed. …
    Not one dime should go to Washington for politicians to pick winners.
    No lobbyists need be employed. …
    It must be clearly explained … that the tax rate will continue to increase in the future.

    When fuel prices decline, the tax should increase, to retain the incentive for transitioning to the post-fossil-fuel-era.
    The effect of reduced fossil fuel demand will be lower fossil fuel prices, making the tax a larger and larger portion of energy costs (for fossil fuels only).
    Thus the country will stop hemorrhaging its wealth to oil-producing nations. …

    A person with several large cars and a large house will have a tax greatly exceeding the dividend.
    A family reducing its carbon footprint to less than average will make money. …
    The dividend will stimulate the economy, spur innovation, and provide money that allows people to purchase low-carbon products and a low-carbon lifestyle. …
    It will increase energy prices, but [people] will find ways to reduce carbon emissions so as to come out ahead. …
    Food requiring lots of carbon emissions to produce and transport will become more expensive … encouraging support of nearby farms as opposed to imports from half way around the world.

    [Imports] from a country that does not apply a comparable carbon tax will be taxed at the port of entry [to prevent leakage.]
    (p 5)

    By itself a carbon tax cannot solve the energy problem and allow rapid coal phase-out.
    There also must be better efficiency standards in building codes, for vehicles, and in appliances and electronics.
    Profit incentives for utilities must be changed, so as to encourage efficiency as opposed to selling as much energy as possible. …
    [However, a carbon tax is an essential] tool that will impact people’s decisions and lifestyle choices for the [short-, middle-] and long-term, allowing the world to move as gracefully as possible to the post-fossil-fuel-era.
    (p 6)

    Nuclear Power

    Who stands ready to ensure that energy needs of China and India will be entirely met by efficiency and renewables? …

    Development of the first large 4th generation nuclear plants may proceed most rapidly if carried out in China or India (or South Korea, which has a significant R&D program), with the full technical cooperation of the United States and/or Europe.


    Priorities for solving the climate and energy problems, while stimulating the economy are steps to:

    1. improve energy efficiency,
    2. develop and deploy renewable energies,
    3. modernize and expand a ‘smart’ electric grid,
    4. develop 4th generation nuclear power,
    5. develop carbon capture and sequestration capability. …

    [Carbon] capture and sequestration (CCS) … could be used at power plants that burn biofuels, such as agricultural wastes.
    This … draws excess CO2 out of the air and puts it back in the ground …
    [It] may be needed to get atmospheric CO2 back to a safe level.
    (p 8)

  • Hansen, James; Lebedeff, Sergej.  Global Trends of Measured Surface Air Temperature, Journal of Geophysical Research, Vol 92, No D11, pp 13,345-13,372, 20 November 1987.

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