Mavericks

James Hansen

22 January 2026

Sophie’s Planet is a difficult book to write because it aims to clarify complex issues about both climate science and climate policy. I find it essential, for my understanding, to read widely on both sides of an issue and to subscribe to both liberal and conservative publications and blogs. Is it only mavericks who can see the flaws that exist on both sides, the reasons why democracies are not working as well as they should? I thought that the task of persuading people of the merits in a different perspective may be insuperable.

What a wonderful surprise to see Gallup Poll results in an article[1] by John Halpin in the Liberal Patriot: the number of people who classify themselves as “Independents” increases with each successive generation until reaching 56% in the youngest generation surveyed (Generation Z, there defined as people born between 1997 and 2007). There must be more mavericks out there than I realized. The open minds of young people are great encouragement to finish Sophie’s Planet soon, as the final chapters focus on suggestions for such independent thinkers.

Here is Part II of the draft Prologue of Sophie’s Planet for fact-checking and criticism. Part III may be delayed a bit, as we have a few other overdue communications.

Prologue: Part II

Wally Broecker, as an undergraduate at Christian fundamentalist Wheaton College in Illinois, learned of a great opportunity to spend the summer of 1952 as an intern at Columbia University’s Lamont Geological Observatory[2] in Palisades, New York, 15 miles north of New York City. Wally fell in love with Lamont, transferred to Columbia, and worked to a Ph.D. in Geology in 1958. Lamont, which has a rich history[3] in geophysical exploration, was Wally’s academic home for the last 67 years of his life.

Wally’s accomplishments were prodigious. His research was guided by paleoclimate records – especially data extracted from polar ice cores and ocean sediment cores[4] that preserve climate change information. He was also a leader in ocean observations: he organized an international survey of the ocean’s chemical constituents, including chemical tracers that help define the ocean’s circulation. These observations helped him investigate interplay among the ocean’s chemistry, biology, and circulation, making him a leading expert in the “carbon cycle” that regulates the carbon dioxide content of Earth’s atmosphere.

Based mainly on ice core evidence of sudden climate changes, Wally concluded that the ocean-atmosphere system had sometimes flipped between different modes of operation and could flip again. He coined the “ocean conveyor” concept to describe the ocean’s overturning circulation and raised concern that human-made climate change could shut down that circulation, thus causing large cooling in the North Atlantic and Europe. He described this threat in simple terms by saying that climate was “an angry beast” that humans were poking with a stick.

Wally was dyslexic, but that handicap spurred him to master oral exchange on scales from one-on-one discussions to workshops and conferences. He visited other laboratories to help develop ideas about climate change; he traveled often to Europe to meet paleoclimate and geochemistry experts. Wally called on colleagues to help with organization of larger meetings. It was a huge opportunity, when he asked me to organize a “Ewing Symposium” in 1982. This was three years after Charney’s study on climate sensitivity, thus a great time to combine information from paleoclimate data and improving global climate models. Today, recent paleoclimate data makes it possible to reconsider issues raised in the Ewing Symposium, allowing a major improvement in understanding of ongoing climate change and more reliable prediction of future change.

In retrospect, the quality of Wally Broecker that I admire most was his courage to speculate. Progress in science depends on people who have the knowledge and the courage to attempt an interpretation of available data, which are always incomplete and contain measurement flaws. This quality is the antithesis of scientific reticence.[5] Sometimes Wally’s proposed interpretations were criticized as a “house of cards,” and, indeed, they often came tumbling down, but even in such cases, he stimulated research. Other scientists criticized his proposal, flaws were exposed, and improvements were made – that is how scientific progress is made rapidly.

The scientific method is needed to understand more than the physics of the climate system. Climate depends on the world’s energy system and the choice of fuels, as much as it does on climate sensitivity. During my career, I had opportunities to witness the making of energy policy and the role of special interest groups in that process. In this prologue, I outline how those opportunities came about. After Charney’s report was published, I worked on a paper that included implications of carbon dioxide emissions for energy policy. Charney liked the paper as a complement to his report and, at my request, he encouraged Phil Abelson, editor of Science, to publish the paper, despite its unusual length. The paper noted the reason that large human-made climate change is inevitable: fossil fuels are the source of rising living standards. Thus, fossil fuel use will not be reduced until unacceptable climate impacts of fossil fuel emissions are proven and the most powerful nations are led by governments willing to follow the science.

The 1980s were difficult for the group of young scientists that I led at the Goddard Institute for Space Studies, as we battled continual attempts to move us to Maryland and refusal of NASA to upgrade our decrepit (1967) computer. Yet we were nourished by our rich environment and the pleasure of finding things out,[6] as we developed our approach at climate analysis based on the combination of paleoclimate data, global modeling, and modern observations. Nevertheless, I was jolted by the reaction of fellow scientists to my congressional testimony in 1988, in which I asserted that a significant effect of humans on global temperature had begun. Skepticism of any assertion is good science, but I was surprised by characterization of my testimony as “Hansen vs. the World.”[7] That reaction seemed to be an almost-angry assertion that I had “jumped the gun.”

In fact, my testimony was well justified, as I will describe in the relevant chapter, but I was not capable or effective in oral debate and I preferred to work on research. Also, the United Nations Environmental Program and the World Meteorological Organization formed an organization, the Intergovernmental Panel on Climate Change (IPCC) in 1988 to address climate change and advise the United Nations. Therefore, after my congressional testimony, I declined interviews with the media for more than a decade. That approach worked well, as we resumed the pleasure of finding things out; my colleagues and I wrote many significant papers in the 1990s.[8] IPCC’s third assessment report (TAR), in 2001, made scores of references to our papers.

By that time, shortcomings of the United Nations political approach to climate change (the Kyoto Protocol) and of the UN’s scientific advisory body (IPCC) were apparent. In a review,[9] I raised two issues. First, IPCC estimated that the Antarctic and Greenland ice sheets would contribute only 5 centimeters (2 inches) to sea level rise by 2100 in their main greenhouse gas scenario, in which atmospheric CO₂ reached 700 ppm[10] by 2100. Such a CO₂ level would dwarf anything that has occurred on Earth in millions of years. IPCC’s sea level estimate was based mainly on GCMs (global climate models). However, paleoclimate data and modern observations suggest that sea level rise is a more serious threat. Second, non-CO₂ climate forcings – methane, ozone, black soot and other air pollutants – may together play a role in climate change almost as great as that of CO₂, so they deserve greater attention.

This was when I began to realize that I was a maverick. IPCC did not discuss any energy pathway that averted dangerous human-made climate change, even though that was the objective of the UN Framework Convention on Climate Change.[11] IPCC considered several scenarios for future climate forcings, but, based on paleoclimate evidence, it was clear that all IPCC scenarios were likely to lock in large sea level rise and other large climate effects. Why did IPCC’s advice not include scenarios more successful in limiting climate change? With the help of colleagues, I wrote a paper (Alternative Scenario[12]) with emphasis on reducing non-CO₂ climate forcings and with long-term phasedown of CO₂ emissions, thus keeping global warming by 2100 well under 2°C (3.6°F).[13],[14] Emphasis on reducing health-damaging air pollutants was meant to encourage cooperation with developing nations, where air pollution kills millions of people per year.

This alternative scenario might also reduce political polarization of climate change, which had become associated with Vice President Al Gore and the Democratic party. Gore led the U.S. delegation to the third Conference of the Parties (COP3) that produced the 1997 Kyoto Protocol in which developed nations agreed to reduce greenhouse gas emissions. Republicans historically supported conservation, but there was no chance they would support the Kyoto Protocol. The fossil fuel industry – which funds both political parties, but especially Republicans – strongly opposed the Kyoto Protocol. Thus, the United States did not join the Kyoto Protocol, which required two-thirds approval in the U.S. Senate.
The alternative scenario, in the end, was not welcomed by either Democratic or Republican administrations. Communication with Vice President Gore’s office, which was already frosty,[15] practically ceased. After George W. Bush assumed the Presidency in 2001, I was invited to speak at the first two Cabinet-level-only meetings of Bush’s Climate and Energy Task Force chaired by Vice President Cheney, who quoted approvingly[16] from our alternative scenario paper. However, after it was realized that the alternative scenario called for phasedown of fossil fuel CO₂ emissions – via some combination of energy efficiency, clean energies, and carbon capture – Cheney lost interest in our paper. Nevertheless, I did not give up on the alternative scenario.

Even as a government employee, I could seek support for an international workshop to discuss actions to limit climate change and air pollution. By good fortune, I met a Pennsylvania philanthropist, Gerry Lenfest, willing to fund special requests[17] such as the full cost of a workshop at the East-West Center in Honolulu including participation of scientists from China and India. We held two “Air Pollution as a Climate Forcing” workshops in Hawaii, which led to later collaborations with scientists from the East, especially China. These workshops helped to make clear the potential for international cooperation to speed the stabilization of global climate.

Freedom of speech was a reality then. An intense period of education about climate policy arose from a failed government attempt to violate my right of free speech. In December 2005, I gave a talk23 describing the climate threat and the lack of effective policy at the annual meeting of the American Geophysical Union in San Francisco, California. This talk led to calls from the White House to NASA Headquarters that Mark Bowen documented in Censoring Science[18] and on his blog. Subsequently, NASA Public Affairs told me that I must inform them of every media interview request and allow NASA the option of naming a “more appropriate” spokesperson. After they exercised that option several times, I informed Andy Revkin of the New York Times of this process, described by lawyers as “prior restraint.” Prior restraint is a violation of the Constitutional right of free speech, which thus led to an article on the front page of the Times, an expose on the television news program “Sixty Minutes,” and a minor tempest of indignation – real or feigned – of Congresspeople.

This free speech hullabaloo led to a cornucopia of invitations to speak with energy and climate experts and government officials in a dozen countries. In three years, 2006-2008, I received a balanced education, traveling and speaking with environmentalists, but also meeting with utility CEOs and their staffs (people charged with keeping the lights on), and oil and coal executives. NASA political leaders were often displeased with what they viewed as extracurricular activity, but I received encouragement from most NASA employees; and midlevel NASA lawyers made sure that my activity was always within my rights.

This intense period culminated in a workshop with energy experts to assess the actions needed to provide the energy required for high living standards, but in a way that preserved a healthy climate. We held the workshop on Capitol Hill in Washington so that congressional staffers could attend – on 3 November 2008, the day before the U.S Presidential election. I felt that we had developed a good understanding of what was needed. The next evening, I was pleasantly exhausted as my wife Anniek and I settled down to watch election returns come in.

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[1] Halpin J, National politics is a graveyard, The Liberal Patriot, 14 January 2026

[2] Now named the Lamont-Doherty Earth Observatory (LDEO). I refer to LDEO as Lamont

[3] Lamont was established in 1948 after the widow of banker Thomas Lamont gifted Columbia the Lamont estate and $250,000. The President of Columbia University, Dwight Eisenhower, used the estate and funding to induce Prof. Maurice Ewing of the Geology Department, to be Director of Lamont, thus countering an offer of a similar level of support from MIT (Massachusetts Institute of Technology). A few years later, Columbia purchased for $150,000 the first of Lamont’s ships, the Vema, a 62-meter, iron-hulled, schooner propelled by both sails and a diesel engine. A golden era in geoscience exploration was beginning, including the International Geophysical Year (1957-58) and exploration of the Moon and planets. Lamont played a significant role in the explosion of scientific knowledge, in part due to Ewing’s policy that data collected by its ships was available to all researchers. Lamont attracted world-leading scientists in geology, oceanography, paleoclimate, and geochemistry. Fittingly, the pivotal meeting on plate tectonics (The History of the Earth’s Crust, NASA Goddard Institute for Space Studies, 10-11 November, 1966), popularly “continental drift,” took place at nearby Goddard Institute for Space Studies in November 1966, providing intellectual and disciplinary credibility required to overcome scientific resistance to discovery (reticence). Indeed, Ewing was skeptical of the notion of plate tectonics (As the symposium began, Ewing asked Edward Bullard “You don’t believe all this rubbish, do you?”), but his own data, much of it interpreted by his students in the open-minded way that Ewing encouraged, helped to persuade him (Bullard EC. William Maurice Ewing (1906-1974), A Biographical Memoir, National Academy of Sciences, 1980).

[4] Central Antarctica is too cold for snow to melt. As the snow piles up, year after year, it compresses into ice, thus trapping bubbles of air, that allow us to sample how Earth’s atmosphere changed during the past million years. The hard shells of microscopic animals in the ocean, called foraminifera or simply forams, sink to the ocean floor when the animals die and pile up as sediment. The exact chemical properties of these shells preserve information on the ocean conditions over many millions of years.

[5] The great scientist Richard Feynman famously ridiculed scientific reticence, as we will discuss in due course.

[6] Richard Feynman, perhaps second only to Einstein as the greatest scientist of the 20^th century, describes the incentive: Feynman RP. The Pleasure of Finding Things Out, Basic Books, New York, 270 pp, 1999

[7] Kerr RA, Hansen vs. the World on the Greenhouse Threat. Science 244, 1041-3, 1989

[8] Results included, e.g., (1) successful prediction of global cooling by the 1991 Pinatubo volcanic eruption (Hansen J, Lacis A, Ruedy R, Sato M, Potential climate impact of Mount Pinatubo eruption, Geophys Res Lett 19, 215-8, 24 January 1992), (2) conclusion that Earth was out of energy balance by at least 0.5 W/m², with more energy coming in than going out (Hansen J, 42 co-authors, Forcings and chaos in interannual to decadal climate change, J Geophys Res 102, D22, 25,679-720, 1997), (3) conclusion that human-made aerosols caused increased cloud cover with a negative climate forcing of at least −1 W/m², thus a cooling that was offsetting a large part of what would otherwise have been greater global warming (Hansen J, Sato M, Lacis A, Ruedy R, The missing climate forcing, Phil Trans Roy Soc Lond B 352, 231-40, 1997).

[9] Hansen, J.E., 1998: Book review of Sir John Houghton’s Global Warming: The Complete Briefing. J. Atmos. Chem., 30, 409-412

[10] Parts per million. Preindustrial CO₂ amount was about 280 ppm, but by 1988 it had increased to 350 ppm.

[11] At the United Nations Earth Summit in Rio de Janeiro in 1992, the Framework Convention on Climate Change was finalized and signed by U.S. President George H.W. Bush. It was ratified by the U.S. Senate in October 1992 and eventually by almost all the nearly 200 nations of the world. The objective of the Convention is to stabilize greenhouse gas concentrations at a level that prevents “dangerous anthropogenic interference” with climate.

[12] Hansen J, Sato M, Ruedy R, et al. Global warming in the twenty-first century: an alternative scenario, Proc Natl Acad Sci 97, 9875-80, 2000

[13] Hansen J. Can we defuse the global warming time bomb? naturalScience, 2003

[14] Hansen J. Is There Still Time to Avoid “Dangerous Anthropogenic Interference” with Global Climate? A Tribute to Charles David Keeling. American Geophysical Union, San Francisco, California, 6 December 2005

[15] Al Gore’s technical questions about climate were often sent by his assistant – first Katie McGinty and later Rosina Bierbaum – to Tom Karl (NOAA National Climatic Data Center, Asheville, North Carolina), Kevin Trenberth (National Center for Atmospheric Research, Boulder, Colorado), and me (NASA, New York). I learned to be slow in answering questions, so they were usually handled by Karl and Trenberth. Also, I declined a request by Gore’s office to write an op-ed in response to a Greg Easterbrook op-ed in the New York Times that was critical of Gore.

[16] Hansen J. Storms of My Grandchildren. ISBN 978-1-60819-502-2. New York: Bloomsbury, 2009

[17] He explained this generosity by noting that, when he was a ne’er-do-well teenager, his father sent him to work on an Iowa farm, where he learned to respect hard work and trust Iowans.

[18] Bowen, M. Censoring Science: Inside the Political Attack on Dr. James Hansen and the Truth of Global Warming. New York: Dutton, 325 pp, 2008

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