Perspective“No Doubt Left” about Scientific Consensus on Global Warming, Say Experts

Published 25 July 2019

The scientific consensus that humans are causing global warming is likely to have passed 99 percent, according to the lead author of the most authoritative study on the subject, and could rise further after separate research that clears up some of the remaining doubts. The pushback has been political rather than scientific. Among academics who study the climate, the convergence of opinion is probably strengthening, according to one expert. “As expertise in climate science increases, so too does agreement with human-caused global warming,” says one expert.

The scientific consensus that humans are causing global warming is likely to have passed 99 percent, according to the lead author of the most authoritative study on the subject, and could rise further after separate research that clears up some of the remaining doubts.

Jonathan Watts writes in the Guardian that three studies published in Nature and Nature Geoscience use extensive historical data to show there has never been a period in the last 2,000 years when temperature changes have been as fast and extensive as in recent decades.

It had previously been thought that similarly dramatic peaks and troughs might have occurred in the past, including in periods dubbed the Little Ice Age and the Medieval Climate Anomaly. But the three studies use reconstructions based on 700 proxy records of temperature change, such as trees, ice and sediment, from all continents that indicate none of these shifts took place in more than half the globe at any one time.

Previous studies have shown near unanimity among climate scientists that human factors – car exhausts, factory chimneys, forest clearance and other sources of greenhouse gases – are responsible for the exceptional level of global warming.

The pushback has been political rather than scientific. Among academics who study the climate, the convergence of opinion is probably strengthening, according to one expert. “As expertise in climate science increases, so too does agreement with human-caused global warming,” John Cook wrote on the Skeptical Science blog. “The good news is public understanding of the scientific consensus is increasing. The bad news is there is still a lot of work to do yet as climate deniers continue to persistently attack the scientific consensus.”