Consensus reached: 90-100% of climate change scientists agree humans caused recent global warming

A consensus on a consensus of climate change scientists has been reached, with 90 to 100% agreeing recent global warming is a result of human activities. A team of scientists was following up on a 'controversial' research paper released in 2013 that said 97% of climate scientists agree recent warming is man made.

Following its release in Environmental Research Letters, John Cook's paper received widespread criticism, with many media outlets questioning the methods used. Cook et al had looked at 11,944 abstracts from the peer-reviewed studies on climate change to find their position on whether warming was man-made, had no opinion on anthropogenic (man-made) global warming, or if they disagreed humans were responsible.

Findings showed 66.4% had no opinion on the cause of recent global warming, 32.6% said it was man-made, while 0.7% rejected warming being the result of human activities. Of the papers that expressed an opinion on the cause of global warming, 97% said humans are to blame.

In a new study, also published in Environmental Research Letters, researchers carried out six independent consensus studies looking at beliefs about climate change. This included gathering different data through different approaches and included Cook's 2013 paper.

Findings showed that, depending on how expert is defined, the view that climate change is caused by humans is shared by between 90 to 100% of publishing climate scientists. Furthermore, they showed the more of a climate expert those surveyed were, the higher the agreement on mankind's influence on climate became. They called it a "consensus on consensus".

"Those results are consistent with the 97% consensus reported by Cook et al," the study said. There was less consensus in surveys of non-experts including climate change deniers. "We demonstrate that this outcome is not unexpected because the level of consensus correlates with expertise in climate science," it said.

"We examine the available studies and conclude that the finding of 97% consensus in published climate research is robust and consistent with other surveys of climate scientists and peer-reviewed studies."

Michigan Technological University's Sarah Green, one of the group that carried out the research, said the problem with surveys on attitudes towards climate change is that respondents can have a pre-determined point of view and lack scientific expertise.

"The public has a very skewed view of how much disagreement there is in the scientific community," she said, pertaining to the argument that many climate sceptics raise – that there is a lack of scientific consensus on the causes of climate change. "But climate change denial is not about scientific skepticism," she said.

Naomi Oreskes, from Harvard University, was co-author on the Cook paper. Commenting on the latest study, she said: "By compiling and analysing all of this research -- essentially a meta-study of meta-studies -- we've established a consistent picture with high levels of scientific agreement among climate experts."