Americans seem to be cooling toward global warming. Just 57 percent think there is solid evidence the world is getting warmer, down 20 points in just three years, a new poll says. And the share of people who believe pollution caused by humans is causing temperatures to rise has also taken a dip, even as the US and world forums gear up for (准备) possible action against climate change. In a poll of 1,500 adults released by the Pew Research Centre for the People & the Press, the number of people saying there is strong scientific evidence that the Earth has gotten warmer over the past few decades is down from 71 percent in April of last year and from 77 percent when Pew started asking the question in 2006. The number of people who see the situation as a serious problem also has declined. The steepest drop has occurred during the past year, as Congress and the Obama administration have taken steps to control heat-trapping emissions for the first time and international negotiations for a new treaty to slow global warming have been under way. At the same time, there has been mounting scientific evidence of climate change—from melting ice caps to the world’s oceans hitting the highest monthly recorded temperatures this summer. The poll was released a day after 18 scientific organisations wrote Congress to reaffirm the consensus behind global warming. A federal government report recently found that global warming is upsetting the Arctic’s thermostat (恒温器). Only about a third, or 36 percent of the respondents, feel that human activities—such as pollution from power plants, factories and automobiles—are behind a temperature increase. That’s down from 47 percent from 2006 through last year’s poll. "The priority that people give to pollution and environmental concerns and a whole host of other issues is down because of the economy and because of the focus on other things," suggested Andrew Kohut, the director of the research center, which conducted the poll from Sept. 30 to Oct. 4. "When the focus is on other things, people forget and see these issues as less grave," Andrew Weaver said, a professor of climate analysis at the University of Victoria in British Columbia, "and politics could be drowning out scientific awareness.\ What did Congress and the Obama administration do for slowing global warming

A. Collecting the evidence of climate change.
B. Taking action to limit emissions which absorb heat.
C. Recording the highest temperature in a year.
D. Negotiating a new treaty for reducing the emissions.