The issue of climate change, or global warming, has become a rallying cry: The Earth’s surface temperatures are ­rising due to increased levels of carbon dioxide and other ­greenhouse gases in the atmosphere, much of it produced by human activity. Unless action is taken, and soon, global warming could cause crops to fail and sea levels to rise, leading to ­widespread social disruptions and endangering many species of life on the planet. President Obama, who has renewed the American commitment to combating this problem, declared at the recent United Nations ­climate-change conference in Copenhagen: “Climate change threatens us all.”

That’s one thing scientists agree on, right? Well, not everyone.

In some quarters, climate change has become almost a civic religion. Like any religion it has its priests — Al   Gore, perhaps — and its holy books — think Gore’s An Inconvenient Truth or his more provocatively titled best-seller, Earth in the Balance. It also has its heretics — doubters — and not all of them are outside the scientific community. Even among scientists, there are a few who dispute the certainty that global warming is a looming catastrophe. Two of the most vocal dissenters are professors in the Princeton physics department: William Happer *64 and Robert Austin.  

One person’s skeptic is another person’s crackpot, of course, and so climate dissenters have come in for much public abuse. Happer, the Cyrus Fogg Bracket Professor of Physics, got into a contretemps with Sen. Barbara Boxer, a California Democrat, while testifying last year before the Senate Environment and Public Works Committee. Boxer derided Happer’s testimony as “the most extraordinary argument I have ever heard” and warned, “I will fight you.” The exchange, which ended up on YouTube, was seized upon by bloggers on both sides of the debate, many of whom added their own, decidedly ad hominem, comments.

Temperatures indeed have risen, so to speak — at least in the world of physics. Happer says he’s been attacked verbally over the issue both inside and outside academia, including at Princeton. He claims that climate-change orthodoxy has had a chilling effect that has made some junior faculty around the country reluctant to voice support for his position out of fear of hurting their chances for tenure. Austin, however, says that in his experience, the Princeton physics department “has been great” and very tolerant of climate skeptics.

In an interview last year with The Daily Princetonian, Happer characterized hostility toward climate skeptics in harsh terms. “This is George Orwell,” he said. “This is ‘the Germans are the master race. The Jews are the scum of the earth.’ It’s that kind of propaganda.” In an e-mail following an interview for this article, he warns against “the capture of U.S. society” by a “scientific-technological elite.”

Although Happer credits some of his willingness to brave personal and professional criticism as an expression of his Huguenot ancestry, he adds that he has spent much of his career studying the interaction of visible and infrared radiation with gases, one of the driving forces of the greenhouse effect, which posits that CO2 in the atmosphere absorbs and redirects infrared radiation, causing temperatures to rise. Happer joined the Princeton faculty in 1980, leaving in 1991 to become director of energy research at the U.S. Depart­ment of Energy, where one of his responsibilities was to supervise the department’s work on climate change. In 1993, however, shortly after President Clinton took office, Happer testified at a House hearing that he believed that “there has been some exaggeration” concerning the dangers of ozone and climate change, an act of apostasy that he says led to his being replaced.

Since returning to the faculty, Happer has gained distinction for his work in other fields. He helped patent an invention that provides high-resolution images of the human lung. From 1995 to 2005, he led the University Research Board, which advises the University president on all research conducted at Princeton. He currently runs a lab in atomic physics and is chairman of the board of directors of the George C. Marshall Institute, an Arlington, Va.-based think tank founded by Frederick Seitz *34, himself a climate-change dissenter before his death in 2008.

Austin, a biophysicist, says that he had always “bought the party line” on climate change until he began talking to Happer. “I’ve always known Will Happer as a guy who usually has creative and insightful things to say that are not part of the mainstream,” Austin explains. Happer explained his disagreements with the climate-change consensus and brought Austin around to his position. Austin has since visited the Greenland glaciers with physicist Freeman Dyson of the Institute for Advanced Study — another ­climate-change skeptic — and says that while some glaciers may be shrinking at the edges, evidence suggests that they may be getting thicker in the middle.  

Much of the climate-change debate centers on a 2007 statement adopted by the American Physics Society (APS), a leading professional association of physicists: “The evidence is incontrovertible: Global warming is occurring. If no mitigating actions are taken, significant disruptions in the Earth’s physical and ecological systems, social systems, security, and human health are likely to occur. We must reduce emissions of greenhouse gases, beginning now.”

Austin, Happer, and a handful of other scientists urged the APS to rescind this statement in favor of one stating, “While substantial concern has been expressed that emissions may cause significant climate change, measured or reconstructed temperature records indicate that 20th- and 21st-century climate changes are neither exceptional nor persistent, and the historical and geological records show many periods warmer than today.” It goes on to say that other forces, such as ocean cycles and solar variability, also might account for rising temperatures. “Current climate models,” it concludes, “appear insufficiently reliable to properly account for natural and anthropogenic contributions to past climate change, much less project future climate.” More than 160 past and present members of the APS signed their petition, including two other Princeton faculty members: Salvatore Torquato, a professor of chemistry, and Syzmon Suckewer, a professor of mechanical and aerospace engineering.

In response, the APS appointed an advisory committee to consider changes to its climate statement. Last November, that committee recommended that the APS stand behind the conclusions expressed in its statement, although it suggested that the society’s panel on public affairs address certain issues “of clarity and tone” in the way parts of the resolution were phrased. The society’s governing body then unanimously defeated Austin’s and Happer’s proposal, with Austin himself voting against it. He explains that while he continues to believe the APS’s 2007 statement ought to be changed, he became unhappy with phrasing in his own alternative and concluded that it too needed to be revised. He has not, however, introduced another alternative. Meanwhile, the APS’s public-affairs panel is preparing a commentary about the 2007 statement and the science behind it. That panel is led by Princeton professor Robert Socolow, an influential researcher who studies technologies to reduce carbon emissions.

Climate-change skeptics and believers agree on many of the facts; where they differ is in the conclusions to be drawn from them. Both, for example, agree that the earth’s climate is changing, that surface temperatures are rising, and that glaciers, at least in some areas of the world, are shrinking.   They agree that burning fossil fuels adds to CO2 levels in the atmosphere. Where the dissenters diverge most sharply from the consensus is in their disagreement that human activity is responsible for the changing climate and their refusal to extrapolate from current conditions to ecological disaster.  

Happer, for example, says that climate-change advocates ignore the fact that there have been several periods, including the last 10 years, in which there has been no warming, and that temperatures in fact cooled during the period from roughly 1940 to 1970. Sea levels are indeed rising, he also says, but they have been rising since the end of the last Ice Age, and there is no evidence that the rate is increasing.   Suckewer adds that his own research has convinced him that human activity has little to do with rising CO2 levels, much of which is caused by water vapor and ocean currents.   Those forces, he says, are so vast, complex, and imperfectly understood that efforts to “fix” them would be folly.

According to Happer, computer models developed by the Intergovernmental Panel on Climate Change (IPCC), on which many climatologists base their projections about the effects of greenhouse-gas emissions, fail to account for recent periods of global cooling. If the models can’t accurately reproduce the past, Happer and others ask, how reliable can they be in predicting the future? The IPCC shared the 2007 Nobel Peace Prize with Gore for their work on climate change.  

Like his ally Dyson, Happer argues provocatively that rising CO2 levels are in fact a net boon, and that humanity would be better off if they were even higher. Plants and early humans, Happer testified, evolved when CO2 levels were about 1,000 parts per million, far higher than they are today (about 380 parts per million) or are likely to become even under dire global-warming scenarios, with no adverse effects on life. Rising CO2 levels have, if anything, benefited mankind by increasing crop yields and making more parts of the globe available for cultivation.    

Austin, a biological physicist, also does not question data that show that global warming has occurred, but he questions projections derived from those data. CO2 levels have been much higher in the past, but this did not induce a tipping point, as some have suggested, in which surface temperatures soared to dangerous levels. Instead, temperatures during earlier periods of CO2 increases seem to have self-regulated, reaching a plateau and then slowly declining. Austin believes it is a question whether they will do so again, in which case dire forecasts of devastating climate change will not come to pass.

In addition to fighting the APS, climate skeptics have aimed their arguments outside the scientific community.   Austin and Happer, along with five other colleagues in academia and the petroleum industry, circulated a letter to Congress last July in response to a letter from scientists at the Woods Hole Research Center calling for immediate action to combat global warming. They suggested that the center was politically biased, calling it “the former den” of John Holden, now President Obama’s science adviser. As for evidence that purports to prove global warming, the letter insisted, in bold caps: THERE IS NO SUCH EVIDENCE; IT DOESN’T EXIST.

Skeptics received a boost last November when e-mails stolen from the climate-research unit of the University of East Anglia in England seemed to suggest that researchers had modified data to support global-warming theories, contemplated deleting data that might contradict those theories, and discussed ways to pressure an academic journal not to publish submissions from skeptics. The press quickly dubbed the matter Climategate. Scientists at the center say that the e-mails were misunderstood or taken out of context, and in February, an academic board of inquiry largely cleared a noted climatologist involved in the controversy of scientific misconduct. But climate-change proponents suffered further embarrassment when it was revealed that a projection in an IPCC report that claimed the Himalayan glaciers could disappear within the next few decades was wildly — some say deliberately — exaggerated, an incident that naturally came to be dubbed Glaciergate.

“Climategate” prompted Austin, Happer, and three others to circulate another letter to APS members in which they characterized the East Anglia e-mails as “an international scientific fraud, the worst any of us have seen in our cumulative 223 years of APS membership” and renewed their call for the society to withdraw its 2007 policy statement and “clarify the real state of the art in the best tradition of a learned society.”    

If the evidence supporting the implications of global warming is as flimsy as skeptics claim, why do so many prominent scientists agree that it is being driven by human greenhouse-gas emissions and should be curbed? Happer suggests that only a few actually have looked at the raw data and that others, too busy to do so themselves, have accepted what their colleagues have told them, falling into a dangerous form of groupthink. Furthermore, that consensus has become self-perpetuating. “A huge constituency has grown up that makes a living off” advocating action to combat global warming, Happer insists. For example, he dismisses U.S. Energy Secretary Steven Chu, a former professor of physics and molecular biology at the University of California, Berkeley, as someone who has “convinced himself that he needs to save the world, even if it doesn’t need saving.”

Both Happer and Austin express regret that the climate-change issue has become conflated with simple environmentalism, which they say they support. “In a perfect world,” Austin says, “I would like to see us do everything in our power to develop alternatives to fossil fuel. I am all in favor of sustainability.” Happer said in his Senate testimony, “We should not confuse these laudable goals [such as protecting the environment and ending dependence on foreign oil] with hysterics about carbon footprints.”

Given the possibly dire consequences of global warming, would it not be prudent to curb greenhouse-gas emissions anyway? Happer dismisses that argument, known as a precautionary principle, as harmful to American economic competitiveness and wasteful of our time and energies. “You can make that argument about anything,” he says. More to the point, “It is corrupting to the body politic to live on a lie,” and he compares climate-change correctness to Newspeak in George Orwell’s 1984.  

Austin advocates a level of agnosticism as the best professional posture. “In the physics community, we are supposed to be skeptics,” he says, noting that most scientific breakthroughs, dating back to Galileo and Newton, came from scientists who refused to accept settled assumptions. What is necessary, he says, is to insist on getting as much data as possible, evaluating the information objectively, and reaching one’s own conclusions. It should be pointed out, however, that those who accept the consensus on climate change do not disagree with this principle, but they believe that the evidence is now clear enough that action ought to be taken.

Michael Lemonick, a Princeton visiting lecturer and senior writer for Climate Central, a group that aims to “create a bridge between the scientific community and the public,” fears the impact of the scientific skeptics. “The fact that something is false does not keep it from shifting the public debate,” he says. “We could well decide not to do much about global warming based on false assertions.”

Almost everyone seems to agree that the science has become dangerously politicized. Socolow recognizes that a “group of members of the APS” are unhappy with the 2007 statement, and says the society is responding to their criticisms. “I am doing my best to play a constructive role in that response,” he says. Socolow supports a proposal that Austin has advanced, which calls on the APS to create a special panel to conduct further research on climate change, whether or not the society amends its 2007 statement.  

Austin hopes a panel could remove some of the politics from the debate. “I would like to see it be a place,” he says, “where people could leave their ideological guns at the door.”  

Mark F. Bernstein ’83 is PAW’s senior writer.