Four years ago in New Hampshire, campaigning for the Republican presidential nomination, John McCain said to voters, “I do agree with the majority of scientific opinion, that climate change is taking place and it’s a result of human activity, which generates greenhouse gases.” He made global warming a key element of every New Hampshire stump speech.
This week in New Hampshire, the governor of Texas and newest presidential contender, Rick Perry, said scientists have manipulated data to support their “unproven” theory of human-influenced global warming. He said increasing numbers of scientists have disavowed the theory altogether.
This is not simply a case of two very different politicians saying two very different things. The political discussion about global warming has lurched dramatically in four years — even as the scientific consensus has changed little. McCain’s 2007 description remains the scientific consensus: Human activity, including the burning of fossil fuels, is pumping carbon dioxide and other greenhouse gases into the atmosphere and warming the planet.
But that scientific conclusion has become a lively point of debate in the GOP presidential campaign. Joining Perry on the skeptical side, for example, is Rep. Michele Bachmann (R-Minn.), who suggested Wednesday that “manufactured science” underpins what a questioner called the “man-made climate-change myth.”
The nominal GOP front-runner, Mitt Romney, drew sharp fire from conservatives when he said in June that he accepts the scientific view that the planet is getting warmer and that humans are part of the reason. Former Utah governor Jon Huntsman Jr. (R) on Thursday tweeted: “To be clear. I believe in evolution and trust scientists on global warming. Call me crazy.”
“Climate change has become a wedge issue,” said Roger Pielke Jr., a University of Colorado professor who has written extensively on the climate debate. “It’s today’s flag-burning or today’s partial-birth-abortion issue.”
Historically, climate change has ranked near the bottom of issues that voters care about as they evaluate presidential candidates. It wasn’t a factor in 2008’s primary season or general election. The major parties’ nominees endorsed the scientific consensus and believed that the government should curb carbon emissions.
But even as it appeared that the government might take sweeping action on climate change, the political opposition intensified. President Obama favored a nationwide system in which industries would have to cap their carbon dioxide emissions and trade pollution allowances with one another. The then-Democratic-controlled House passed this “cap-and-trade” system in June 2009, but the plan stalled in the Senate after Republicans and major industries criticized it as a “cap-and-tax” system that would escalate energy costs.
The battleground shifted to the Environmental Protection Agency, which in December 2009 determined that greenhouse gases pose a threat to public health and welfare. That “endangerment finding” paved the way for regulating carbon dioxide as a pollutant under the Clean Air Act. GOP lawmakers and industry groups fought the plan, calling it a job-killing tax and an example of government overreach.
During this period, Americans — particularly conservative Republicans — became less convinced about global-warming science.
Some in the tea party seized on the issue as a rallying cry in last year’s election, which brought dozens of new members to Congress who reject a connection between human activity and climate change.
Missteps by scientists have given critics ammunition. Most notorious were “Climate-gate” e-mails hacked from computers at the Climate Research Unit at the University of East Anglia in Britain in 2009. The e-mails showed scientists being combative and clubby, but multiple investigations in both the United States and Britain cleared the researchers of scientific misconduct, concluding that there was no evidence they tried to cook the books, as critics had alleged.
Embarrassing errors were also found in a seminal 2007 report by the U.N. Intergovernmental Panel on Climate Change, which was supposed to establish, beyond question, the scientific consensus. One passage in the 3,000-page report, for example, stated that massive glaciers in the Himalayas would vanish by 2035 — which isn’t true.
Such missteps revealed that the scientific establishment does not always function like a well-oiled machine and that climate science in the raw is a more contentious enterprise than the average academic news release might suggest. But the errors did not change the basic science behind the theory of anthropogenic, or human-caused, global warming.