We can now give you a figure: 99.9%.
This doesn't leave much to doubt. Researchers looked at a total 3,000 peer-reviewed papers randomly chosen from a list 88,125 climate related papers. They found that only four of them doubted that human activity is causing climate shifts.
A similar study was conducted in 2012 and papers from 1991 to 2012 were 97 percent certain. It would seem that this small amount of skepticism has been decreasing over the years.
"We are almost certain that there is consensus at well over 99 percent and that it's pretty much closed for any meaningful public discussion about the reality of human-caused global warming," states Mark Lynas from the Alliance for Science at Cornell University.
Even though there is almost universal agreement in science, over a third of Americans don't believe that global warming is the main cause of climate change. Some political circles also have doubts.
The team looked at 3,000 papers and used a keyword-based algorithm to rank all 88,125 papers according to anthropogenic climate change skepticism. 28 papers were labeled implicitly or explicit'skeptical'.
This is similar to the consensus level on plate tectonics and evolution. The team also claims that the large number of studies that have been done to analyze climate change data leaves little room for debate when it comes time to discuss the science behind the phenomenon.
Lynas says, "To understand where there is consensus, you must be able quantify it."
"This means that we must examine the literature in a cohesive and non-arbitrary manner in order to avoid cherry-picking papers being traded, which is often how these arguments are presented in the public sphere."
It's unclear, however, if this weight of scientific opinions is being actually noticed by the public. Only 27 percent of Americans believe that scientists agree on most of the causes of climate change. In comparison, 55 percent of Americans think almost all scientists agree that the MMR vaccine can be safe.
Although this study does not attempt to answer the question why scientists believe something is different from what the public believes, other researchers have suggested some possible explanations for the spread of disinformation.
It is also clear that human activity has been responsible for global warming. This is due to greenhouse gas emissions. The COP26 global climate summit will be held in the UK at end of March. This gives world leaders another opportunity to take the necessary drastic steps to reduce the planet's warming.
"It is crucial to recognize the primary role of greenhouse gas emission so that we can quickly mobilize new solutions," Benjamin Houlton from Cornell University, an environmental scientist.
The research was published in Environmental Research Letters.
