The lack of fervor about climate change is also true of the United States, where action on climate and emissions reduction is still very much a work in progress, and concern about global warming was never as strong as in Europe. A March Gallup poll found that 48 percent of Americans believed that the seriousness of global warming was “generally exaggerated,” up from 41 percent a year ago.

Here in Britain, the change has been driven by the news media’s intensive coverage of a series of climate science controversies unearthed and highlighted by skeptics since November. These include the unauthorized release of e-mail messages from prominent British climate scientists at the University of East Anglia that skeptics cited as evidence that researchers were overstating the evidence for global warming and the discovery of errors in a United Nations climate report.

Two independent reviews later found no evidence that the East Anglia researchers had actively distorted climate data, but heavy press coverage had already left an impression that the scientists had schemed to repress data. Then there was the unusually cold winter in Northern Europe and the United States, which may have reinforced a perception that the Earth was not warming. (Data from the National Oceanic and Atmospheric Administration, a United States agency, show that globally, this winter was the fifth warmest in history.)

Asked about his views on global warming on a recent evening, Brian George, a 30-year-old builder from southeast London, mused, “It was extremely cold in January, wasn’t it?”

In a telephone interview, Nicholas Stern, a former chief economist at the World Bank and a climate change expert, said that the shift in opinion “hadn’t helped” efforts to come up with strong policy in a number of countries. But he predicted that it would be overcome, not least because the science was so clear on the warming trend.

“I don’t think it will be problematic in the long run,” he said, adding that in Britain, at least, politicians “are ahead of the public anyway.” Indeed, once Mr. Cameron became prime minister, he vowed to run “the greenest government in our history” and proposed projects like a more efficient national electricity grid.

Scientists have meanwhile awakened to the public’s misgivings and are increasingly fighting back. An editorial in the prestigious journal Nature said climate deniers were using “every means at their disposal to undermine science and scientists” and urged scientists to counterattack. Scientists in France, the Netherlands and the United States have signed open letters affirming their trust in climate change evidence, including one published on May 7 in the journal Science.