Stanford University recently conducted a study that shows a minimal number of scientists who do not accept that human beings have contributed to the Earth's climate change have "far less expertise and prominence in climate research" than scientists who do believe climate change has been affected by humans. 

The university came to these conclusions by analyzing the number of research papers published "by more than 900 climate researchers" and the number of times these researchers' works were cited by other scientists. The expertise was evaluated by citing the number of research papers written by scientists (with the minimum number for inclusion being 20).

Prominence was analyzed by finding the four most popular climate change and non-climate change papers published by scientists, and "tallying" the number of times these papers were cited. According to the results, approximately 64 percent of papers by climate researchers convinced of human contribution were cited more often than those who are unconvinced. 

"These are standard academic metrics used when universities are making hiring or tenure decisions," said William Anderegg, lead author of a paper published in Proceedings of the National Academy of Sciences.

The scientists who participated in the study were also involved in creating the 2007 report of the Intergovernmental Panel on Climate Change (IPCC), which compiled and "assessed the evidence for and against human involvement in climate change, as well as any climate researchers who signed a major public statement disagreeing with the findings of the panel's report."

In addition, the university's team of scientists decided on who the top 100 climate researchers are by determining the "total number of climate-related publications each had." According to Anderegg, 97 percent of those in the top 100 agree with and/or endorse the IPCC's assessment. He also says that this result has been "borne out" by other studies that use different methodology.  

"We really wanted to bring the expertise dimension into this whole discussion," said Anderegg. "We hope to put to rest the notion that keeps being repeated in the media and by some members of the public that 'the scientists disagree' about whether human activity is contributing to climate change."

The scientists at Stanford have mentioned that they are ready to take some heat from doubters of anthropogenic, or human-affected, climate change who "object to their data." But according to Stephen Schneider, a professor of biology and a coauthor of the paper in Proceedings of the National Academy of Sciences, the team "took pains to avoid any sort of prejudice or skewed data in their analysis." When selecting researchers for the study who either disagreed with statements of the IPCC or signed the petitions, the Stanford team was sure to stay completely neutral in the study by omitting "those who had no published papers in the climate literature."

Schneider says that despite the careful analysis of this study, skeptics of human-affected climate change will "claim foul" anyway, and will say that climate researchers who are onboard with the idea of anthropogenic climate change are "just trying to deny publication of the doubters' opinion," but he challenges them to "go out and do a study to prove it -- it is of course not true."

"I think the most typical criticism of a paper like this -- not necessarily in academic discourse, but in the broader context -- is going to be that we haven't addressed these sorts of differences could be due to some clique or, at the extreme, a conspiracy of the researchers who are convinced of climate change," Anderegg said. 

"When you stop to consider whether some sort of 'group think' really drives these patterns and it could really exist in science in general, the idea is really pretty laughable," he said. "All of the incentives in science are exactly the opposite."

This Stanford study is the first of its kind to address the issue of scientists' opinions of human-affected climate change, and what their level of expertise and prominence in the field is.