Once a relatively revolutionary theory without much mainstream support, climate change is now mostly an accepted notion that has engaged national governments worldwide in search of effective ways to reduce CO2 emissions. According to NASA's Goddard Institute for Space Studies, 2020 tied with 2016 as the hottest year on record since 1880.

Moreover, 19 of the hottest years since record keeping began have occurred since 2000. More than 196 parties, including governments, signed the Paris Agreement in 2015 to restrict global warming to 1.5 degrees Celsius relative to pre-industrial levels.

Debates about the reality of climate change—and its cause(s)—have been ongoing for quite some time. However, a recent survey conducted by academics at Cornell University found that 99.9 percent of peer-reviewed scientific papers conclude human beings largely contributed to the rapid heating of the earth's surface.

Cornell University Survey Results

The authors of the paper, "Greater than 99% Consensus on Human Caused Climate Change in the Peer-Reviewed Scientific Literature," examined 88,125 climate-related studies published from 2012 to 2020. They used an algorithm to detect key words related to skepticism such as "cosmic rays," "natural cycles," and "solar."

Only 28 of the 88,125 papers were implicitly or explicitly skeptical, and all of these were published in lesser-known journals. A similar survey in 2013 found that 97 percent of papers published between 1991 and 2012 agreed with the notion that climate change was caused in part by human activity.

"We are virtually certain that the consensus is well over 99 percent now and that it's pretty much case closed for any meaningful public conversation about the reality of human-caused climate change," noted Mark Lynas, a co-author of the paper and visiting fellow at the Alliance for Science at Cornell University.

Changing Perception Among Americans

Studies have also shown that more Americans are beginning to take climate change seriously. In 2020, the Yale Program on Climate Change (YPCC) found that 26 percent of Americans were feeling alarmed about global warming. Only 11 percent of respondents were doubtful and 7 percent dismissive about the realities of climate change. A similar poll conducted by YPCC found only 11 percent of respondents were alarmed in 2015, with 15 percent doubtful and 12 percent dismissive.

Yet, in 2016, the Pew Research Center conducted a study that showed only 27 percent of adults in the United States believed "almost all" scientists were in agreement on human beings exacerbating the effects of climate change. Moreover, a 2018 Gallup poll found that only 45 percent of Americans believed climate change would affect them personally.