Findings confirm reliability of projections of temperature changes over last 50 years
Climate models have accurately predicted global heating for the past 50 years, a study has found.
The findings confirm that since as early as 1970, climate scientists have had a solid fundamental understanding of the Earth’s climate system and the ability to project how it will respond to continued increases in the greenhouse effect. Since climate models have accurately anticipated global temperature changes so far, we can expect projections of future warming to be reliable as well.
The research examines the accuracy of 17 models published over the past five decades, beginning with a 1970 study and including 1981 and 1988 models led by James Hansen, the former Nasa climatologist who testified to the US Senate in 1988 about the impacts of anthropogenic global heating. The study also includes the first four reports by the UN’s intergovernmental panel on climate change (IPCC).
“We found that climate models – even those published back in the 1970s – did remarkably well, with 14 out of the 17 model projections indistinguishable from what actually occurred,” said Zeke Hausfather, of the University of California, Berkeley, and lead author of the paper.
Based on modern climate model projections, if countries follow through with current and pledged climate policies, the world is on track for about 3C of warming above pre-industrial temperatures by 2100 – a situation the IPCC and others predict would be catastrophic.
The challenge in evaluating climate model accuracy lies in the fact that due to computing power limitations, simulations are only run for a few specific future greenhouse gas emissions scenarios. There are an infinite number of such possible scenarios, but real-world emissions will follow only one path, and it will never exactly match the few scenarios input into climate models. Thus, if Earth warms less than in a climate model projection, it does not necessarily mean the model was inaccurate.