After slumping over the past few years, public acceptance of the scientific conclusion that global warming is happening appears to be on the upswing, according to a pair of recent national polls.

Various reasons have been suggested for the decline in public agreement with the view, held by the vast majority of scientists, that the earth’s climate is heating up. Among them are the economic downturn (economic troubles traditionally correlate with lower environmental concern) and a hardening of many Republicans’ skepticism about manmade climate change and Democrat-championed initiatives to address it.

Whatever the case may be, Gallup’s latest survey on the issue, released March 30 and based on polling from March 8-11, found a slight increase in agreement with the statement that “the effects of global warming … have already begun to happen.”

Fifty-two percent of respondents concurred with that statement following a steady decline from Gallup’s all-time high finding of 61 percent who agreed in 2008 to 49 percent in 2011).

At the same time, Gallup found in the 2012 survey that attribution of a warming climate trend to human causes has continued to increase.

Asked their opinion of the primary cause of global warming, 53 percent of survey participants said it was “the effects of pollution from human activities,” while 41 percent chose “natural changes in the environment that are not due to human activities.”

In a 2007 Gallup poll, 61 percent had said “human activities” and 35 percent had said “natural changes.” The gap narrowed to 50 percent for “human activities” versus 46 percent for “natural changes” in 2010, but has been widening since then in favor of a bigger margin for “human activities.”

In the latest survey, Gallup found a continuing partisan divide on these and other climate-related questions that the survey organization posed:

Across all four Gallup measures of views on global warming, the majority of Americans lean toward believing in it. Independents’ views are similar to the national averages, while much larger percentages of Democrats are supportive. Republicans, on the other hand, are largely skeptical.

The highest support for global warming claims among Republicans is seen on the scientific consensus question, with 43 percent saying most scientists believe global warming is happening. Republicans’ agreement is much lower on the question of news reports about global warming, with 31 percent saying those reports are accurate or underestimate the problem.

Gallup’s analysts saw little effect from recent, much-warmer-than-normal weather across much of the U.S. on poll respondents’ attitudes:

Some shift in Americans’ global warming views might have been expected this year, given the near-record warm temperatures experienced this winter across much of the country – Gallup finds 79 percent of Americans reporting that the weather in their area was warmer than usual, though less than half of these attributed this to global warming.

However, the fact that belief in global warming did not increase markedly suggests Americans are basing their perceptions more on the debates over scientific evidence than on the weather outside their front door.

In contrast, however, a second national poll recently found a notable increase in evidence that people’s own experience of warmer temperatures was a key factor behind their growing agreement that global warming is happening. (Climate scientists warn against confusing short-term weather patterns with long-term climate change, which includes those patterns.)

This second survey was conducted by researchers at the University of Michigan and Pennsylvania’s Muhlenberg College in December as the latest edition of their National Survey of American Public Opinion on Climate Change, which dates to 2008.

By the large margin of 62 percent to 26 percent, respondents said they believe there is “solid evidence that the average temperature on Earth has been getting warmer.”

The researchers noted that the 62 percent “belief” response was the highest in their climate polls since 2009.

Seventy-eight percent of Democrats thought there was “solid evidence” of a warming climate (15 percent did not), compared to a 47-42, yes-no split in favor of “solid evidence” among Republicans and a 55-30 split among independents.

Regarding the findings about respondents’ reasons for their views, the researchers wrote:

The 24 percent of respondents citing observations of warmer temperatures as the main reason behind their beliefs regarding climate change is the highest level since the question was first asked in 2008 and equal to the number of Americans that point to changing or extreme weather as the main factor why they believe climate change is occurring. In all, about half of Americans now point to observations of temperature changes and weather as the main reasons they believe global warming is taking place.

Unlike the Gallup Survey, the Michigan-Muhlenberg team did not ask questions to elicit opinions on the causes of global warming.

Another recently released study, based on a variety of U.S. and international opinion polls, concluded that worsening economic conditions were probably the main cause in the last few years of reduced public agreement that global warming has been occurring.

USA Today reported on this study, published in February:

“We suggest that the decline in belief about climate change is most likely driven by the economic insecurity caused by the Great Recession,” political scientists Lyle Scruggs and Salil Benegal of the University of Connecticut write in the study.

The economy is even more of a factor than partisan politics, supposed biased media coverage, or changeable weather, they say.

[…]

“We would suggest that it is misreading public opinion to dismiss the impact of the current economic crisis and to blame the problem mainly on disinformation or the weather,” the authors write. “Given what we know about recent and historic patterns, it seems probable that climate change opinion will rebound as the economy, and more specifically the job situation, improves.”

– Bill Dawson