The percentage of Americans who believe global warming is real dropped slightly from 80% in 2008 to 75% late last year, still a robust majority that reflects a continued agreement with the conclusions of climate science, a leading specialist on survey research told a Capitol Hill briefing co-sponsored by AAAS.
Jon A. Krosnick, professor of communication, political science and psychology at Stanford University, said the dip was caused by the recognition that the earth’s average temperature was cooler in 2008 than in previous years rather than a backlash against scientists as a result of recent news stories questioning the credibility of the research effort on climate change.
Krosnick, who has been conducting national surveys on climate change for more than a decade, said his findings differ from other polls, including one by the Pew Research Center last fall, which suggest that there has been a sharp decline in the percentage of Americans who believe there is solid evidence for global warming.
While some analysts say that stolen e-mails, appearing to show some climate scientists trying to squelch their critics, and reports of several errors in a consensus report on climate change have affected public confidence in climate research, Krosnick said there is no evidence in his polling numbers to support that view.
The percentage of people who trust scientists “completely, a lot, or moderately” dipped only slightly from 72% in 2006 to 70% in late 2009, Krosnick said, citing results from his recent survey, sponsored by Stanford’s Woods Institute for the Environment and the Associated Press.
A substantial majority of Americans still support government tax breaks and other policies requiring or encouraging businesses to reduce greenhouse gas emissions and build more efficient cars, buildings and appliances, Krosnick said. In 2006, 82% backed such policies, compared to 77% now, his research shows. Support has remained steady or increased for other measures, such as tax breaks for alternative energy sources and construction of nuclear power plants and increased gas and electricity taxes to reduce use, Krosnick said.
He presented his latest polling results at a 12 March briefing for congressional staff and others on “Climate Policy: Public Perception, Science and the Political Landscape” co-sponsored by the AAAS Center for Science, Technology and Congress, the American Meteorological Society, the American Statistical Society, and the American Geophysical Union. Krosnick was joined by Michael Oppenheimer, professor of geosciences and international affairs at Princeton University, who laid out the scientific evidence for global warming, and Norman Ornstein, resident scholar at the American Enterprise Institute, who discussed how the current political landscape affects prospects for combating climate change.
“There is a truism in survey measurement that you have to bear in mind: question wording matters,” Krosnick said.
“Respondents respond to the words in the questions you ask. The brain can’t help but do so.” While he acknowledged that crafting questions is not easy, Krosnick said that too often, public opinion survey questions on climate change have been poorly worded, lacked balance, or delivered too much information for respondents to quickly process. The result can be polls which suggest a more substantial shift in attitudes toward climate change than is warranted, he said.
Regarding the five-point drop in his own numbers on the percentage of those who believe global warming has been happening, Krosnick said almost all of the change occurred among the minority of Americans who have little trust in scientists.
One instance of widespread misunderstanding, he said, has been caused by the successful efforts of climate change skeptics to convince the public that there is disagreement among scientists on the reality of global warming. Krosnick’s latest survey shows an eight-point drop—from 39% in 2008 to 31% in 2009—in the percentage of people who think most scientists agree that global warming has been happening. And, in fact, for many years, the number of Americans who recognize the extent of the scientific consensus has been smaller than scientists would like.
“Since 1997, only one-third or fewer of Americans have recognized a scientific consensus among natural science experts on this issue,” Krosnick said. He called it “the most striking misperception” in his polling on climate change, one that poses a significant and continuing public education challenge for scientists.
“Scientists are terrible at communicating with the public,” Oppenheimer said. “That’s not a surprise, but something needs to be done about it.” At the same time, he noted, the polling data suggest there is only a tenuous relationship between what scientists say and what the public believes. Many may form their opinions on factors other than the information presented.
Still, the Capitol Hill briefing gave Oppenheimer an opportunity to remind congressional staff and others that—despite the recent media debate on the integrity of climate change researchers—the scientific understanding of global warming is clear and convincing. The natural greenhouse effect, by which water vapor and other gases in the atmosphere trap some of the sun’s heat as it is re-emitted from the Earth’s surface, has been understood for about 200 years, Oppenheimer said.
Without that natural warming mechanism, the Earth’s temperature would be 60 degrees Fahrenheit colder than it is and humans never would have evolved as a species, he said. The problem is that human activity has been pumping up the level of greenhouse gases, primarily due to fossil fuel-burning and deforestation. Total greenhouse gas emissions grew from 28.7 billion tons per year in 1970 to 49 billion tons in 2004.
The accumulation of such gases in the atmosphere is robust and persistent, Oppenheimer said. “Some of the carbon dioxide that you take into your lungs when you breathe was emitted by the first Model T,” he said. It has been estimated that about 20% of the carbon dioxide we emit today by fossil fuel burning will still be in the atmosphere 1,000 years from now, Oppenheimer added.
The measured temperature increase at the Earth’s surface has gone up nearly 1.5 degrees Fahrenheit over the past 100 years, Oppenheimer said. The climate-related changes already underway, he said, include an increase in global average sea level of about 7 inches over the past 150 years. For each foot of sea level rise on the Eastern Seaboard, scientists estimate a loss inland of 100 feet of shore area without adaptations such as sea walls or sand replenishment. Researchers also have documented a 25% seasonal loss of sea ice in the Arctic, greater than the land area of Texas, California and Maryland combined.
Oppenheimer cautioned that even when the overall global trend is toward warming, brief periods of cooling can occur. One computer model foresees just such a period of cooling in Atlantic sea surface temperatures over the next decade. “Don’t be fooled,” he said. The long-term temperature trend in that model and others is upward.
For the future, scientists predict regional changes in which killer heat waves—such as the one which caused an estimated 35,000 deaths in Europe in 2003—may become the norm. Unless steps are taken to mitigate climate change, Oppenheimer said, “By the end of the century, the nasty summer of 2003 becomes just the typical summer.”
The impact of melting ice at the poles and in Greenland on global sea levels, while difficult to predict, could bring disastrous results in some areas. A sea level rise of 1 meter could inundate low-lying areas in Bangladesh where 10 million people now live, Oppenheimer said.
Given the scientific consensus on climate change, what are the prospects for legislation that would begin to cap the amount of greenhouse gas emissions by the United States? Ornstein, who has been watching and analyzing Congress for four decades, said he has never seen a higher level of dysfunction in the legislative process. The partisanship and prolonged bickering over health care reform, he said, has made it harder for lawmakers to move on other issues.
It is remarkable that the House of Representatives, in a sharply polarized environment, was able to pass a climate change bill last year with cap-and-trade provisions, Ornstein said. The odds of passing similar legislation in the Senate were never high, he said. It will require “a very tough, uphill slog” to find regional and ideological coalitions in the Senate to pass a bill, he said.
“It is almost miraculous that we have debate, discussion and even negotiation over climate change,” Ornstein said. The process is “alive and reasonably well right now while moving to a very different plane.”
President Barack Obama is willing to consider expansion of nuclear power and offshore drilling as steps that could bring some Republican senators along. Ornstein said, while Sen. Lindsay Graham (R-South Carolina) has been working with John Kerry (D-Massachusetts) and Joe Lieberman (I-Connecticut) to explore new avenues toward a bipartisan Senate climate bill. That the process remains alive in the current political climate, he said, “is more than I think many of us would have thought six months or a year ago.”