How many scientists agree about climate change?

Research confirms a consensus
The most comprehensive study of scientific views on climate change was published in 2013. The study found more than 97 percent of peer reviewed climate science publications agree people are driving unnatural warming.(1) Research out of Stanford, Harvard and the University of Illinois also independently reached similar conclusions.(2),(3),(4)

PeerReview-01Source: Environmental Research Letters

The 2013 study showed that the agreement around human-driven climate change grew significantly as more research was conducted and the understanding of Earth’s climate improved.


Source: Environmental Research Letters

What does “peer reviewed” mean?
Peer review is a process used in academia to ensure publications meet high accuracy and quality standards.(5) The process relies on independent scientists to anonymously review and critique research by other scientists. Prospective papers that fail to meet these standards are not published.(6)

How was the study conducted?
The study assessed 11,944 peer-reviewed publications on climate science. Each was reviewed by at least two researchers and ranked based on whether they agreed, disagreed, or had no position on human-driven climate change. Of the 4,000 papers that took a position, researchers found nearly 97% agreed with human-driven climate change.

One drawback of this approach is that many studies counted in the 97% simply implied people were causing climate change. For example, studies that look to reduce greenhouse gas emissions are counted as those that acknowledge human greenhouse gases cause climate change. The researchers, recognizing the potential for misinterpretations, also asked the original authors to rank their own papers. Of the authors that responded, more than 96% agreed that people were the main cause of climate change.(7)



All scientists agree that greenhouse gases warm the Earth
The scientific community – including those labeled as climate change “critics” or “skeptics” – universally agrees that greenhouse gases significantly warm the Earth. Most scientists and organizations agree that people are driving unnatural warming by putting extra greenhouse gases into the air.(8) A very small minority disagrees. They believe that recent record-breaking temperatures and other changes are mostly natural and unrelated to human emissions.

Universal agreement rarely exists in science
There’s disagreement about virtually every scientific theory — even those we take for granted. Consider the claim that smoking tobacco is bad for one’s health. Since 1964, the Surgeon General has repeatedly outlined the dangers of smoking and secondhand smoke. The American Cancer Society refers to secondhand smoke as a “known human carcinogen.”(9) The vast majority of doctors agree.

But there are still people, even doctors, who deny that secondhand smoke actually causes any health problems.(10) Almost no scientific theory commands unanimous support. But the overwhelming majority of scientists believes that man-made climate change is real — just as the overwhelming majority of scientists believes that smoking is hazardous to human health.




  1. Environmental Research Letters
  2. Proceedings of the National Academy of Sciences
  3. American Geophysical Union
  4. Science
  5. University of California, Berkeley
  6. City University at New York
  7. Environmental Research Letters
  8. NASA: Consensus
  9. American Cancer Society
  10. Heartland Institute


  1. Environmental Research Letters