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.

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In nearly half of the model projections examined in the paper, the input scenarios were significantly different from the real-world changes in greenhouse gas emissions. As a result, projected temperature changes were only consistent with observed global warming in 10 of the 17 models, with four projecting more warming and three projecting less than subsequently occurred.

However, the study authors addressed these inconsistencies by evaluating the change in temperature per change in “radiative forcing” – the global energy imbalance caused by the increased greenhouse effect and other factors – in models against what happened in the real world. This metric reveals whether the climate models are accurately producing the temperature response to a given emissions change – in essence, whether are accurately simulating the physical response of Earth’s climate system. With this factored in, 14 of the 17 models were accurate.

“The rate of warming we are experiencing today is pretty much exactly what past climate models projected it would be,” said Hausfather.