Melbourne: A comprehensive analysis of 4,000 studies on climate change published over last 21 years has revealed an overwhelming consensus among climate scientists that humans are to blame for global warming, researchers claim.
The study is the most comprehensive yet and identified 4000 summaries, otherwise known as abstracts that stated a position on the cause of recent global warming - 97 per cent of these endorsed the consensus that we are seeing human-made, or anthropogenic, global warming (AGW).
The study went one step further, asking the authors of these papers to rate their entire paper using the same criteria. Over 2000 papers were rated and among those that discussed the cause of recent global warming, 97 per cent endorsed the consensus that it is caused by humans.
The findings are in stark contrast to the public`s position on global warming - a 2012 poll revealed that more than half of Americans either disagree, or are unaware, that scientists overwhelmingly agree that Earth is warming because of human activity.
"Our findings prove that there is a strong scientific agreement about the cause of climate change, despite public perceptions to the contrary," lead author John Cook, from the University of Queensland, said.
"There is a gaping chasm between the actual consensus and the public perception. It`s staggering given the evidence for consensus that less than half of the general public think scientists agree that humans are causing global warming.
"This is significant because when people understand that scientists agree on global warming, they`re more likely to support policies that take action on it," said Cook.
In March 2012, the researchers used the ISI Web of Science database to search for peer-reviewed academic articles published between 1991 and 2011 using two topic searches: "global warming" and "global climate change."
After limiting the selection to peer-reviewed climate science, the study considered 11, 994 papers written by 29, 083 authors in 1,980 different scientific journals.
The abstracts from these papers were randomly distributed between a team of 24 volunteers recruited through the "myth-busting" website skepticalscience.Com, who used set criteria to determine the level to which the abstracts endorsed that humans are the primary cause of global warming.
Each abstract was analysed by two independent, anonymous raters.
From the 11,994 papers, 32.6 per cent endorsed AGW, 66.4 per cent stated no position on AGW, 0.7 per cent rejected AGW and in 0.3 per cent of papers, the authors said the cause of global warming was uncertain.
The study was published in IOP Publishing`s journal Environmental Research Letters.