For the first time since the United States entered a deep recession five years ago, 70% of Americans now say they believe global warming is a reality, according to researchers.

In a report released Thursday by the Yale Project on Climate Change Communication, authors wrote that America’s concern about global warming is now at its highest level since 2008, and that 58% of Americans expressed worries about it.

“Historically Americans have viewed climate change as a distant problem -- distant in time and distant in space -- and perceived that it wasn’t something that involved them,” said environmental scientist and lead author Anthony Leiserowitz. “That gap is beginning to close, however ... we’re seeing a jump in the number of people who believe it will affect them or their families.”

American attitudes on climate change shifted remarkably during the recession. While 71% of Americans said they believed that global warming was real just prior to the recession in late 2008, the number of believers had plummeted to 57% by 2010, according to the study. By the same token, the share of Americans who did not believe in global warming before the recession stood at 10%, whereas today its 12%.


Many climate scientists said they believed public perception changed dramatically after the start of the recession -- in part -- because economic worries took precedence in people’s minds.

In recent years, however, the number of people who say that global warming is real has grown steadily, according to study authors.

“Additional analysis is required to determine why Americans increasingly believe that global warming is happening, but it is likely due to a number of factors, including the record number of extreme weather events that have occurred over the past two years, including heat waves, widespread drought, floods, wildfires and violent storms. Indeed ... more Americans think that the weather in the United States is getting worse.”

Leiserowitz said he expected the trend to continue. While this summer was the third-hottest in the U.S. since record-keeping began in 1895, the entire year is on track to be the nation’s hottest, according to the National Oceanic and Atmospheric Administration.


Among the study’s findings were the following:

-- Those who believe global warming is happening are more certain than those who do not. Over half of Americans who believe global warming is happening (57%) say they are “very” (30%) or “extremely sure” (27%).

-- For the first time since 2008, more than half of Americans (54%) believe global warming is caused mostly by human activities. The proportion of Americans who say it is caused mostly by natural changes in the environment has declined to 30%.

-- A growing number of Americans believe global warming is already harming people both at home and abroad. Four in 10 say people around the world are being harmed right now by climate change, while 36% say global warming is currently harming people in the United States.


The study conclusions were based on a survey of 1,061 American adults. The survey was conducted online and took roughly 25 minutes to complete. The sampling was random and respondents who did not have a computer or Internet connection were provided with one.

While study authors surmise that two years of extreme weather events are likely responsible for shifting America’s perception of climate change, climate scientists themselves disagree over what weather events, if any, can be tied to global warming.

William Patzert, a NASA climatologist and oceanographer, said that while it was clear that the planet was warming due to human production of greenhouse gases, it was less clear to him that recent droughts and record-breaking heat were direct results.

“Have these events been a preview of coming attractions? The answer is, maybe,” Patzert said. “There are all kinds of scenarios. You know, there is a possibility that floods and droughts will become less intense. But the important thing to realize is that climate will shift. Patterns of rainfall and temperature, upon which our present civilization was built, will change in unknown ways, and that’s scary.”


Despite disagreement among scientists over global warming’s link to extreme weather events, a growing number of Americans say their minds have already been made up.

Over the past year and a half, according to the Yale study, a growing number of Americans say they have all the information they need to form a firm opinion about global warming, from 23% in May of last year to 30% today.

But a solid majority -- 70% -- said they would like at least a “little more” information on the subject, study authors wrote.