Recent global warming trends are consistent with very high climate sensitivity

Research published this week in Earth System Dynamics reports that the most sensitive climate models have overestimated global warming in the last 50 years.

Three scientists from the University of Exeter studied the performance of complex climate models and compared them with temperature observations since the 1970s.

Recent developments in cloud modeling have produced models that show a high sensitivity to increasing greenhouse gas concentrations.

A subset of models even showed that a doubling of CO₂ can lead to more than 5 ° C of warming, the question of whether the goals of the Paris Agreement are achievable, even if peoples do everything they can.

The lead author of the study, Ph.D. candidate Femke Nijsse from the University of Exeter, said: “In evaluating the climate models, we were able to exploit the fact that thanks to clean air regulation, air pollution in the form of climate-cooling aerosols continues to increase worldwide, causing the greenhouse gas signal to to dominate the last warm-up. “

The amount of warming that occurs after CO₂ concentrations in the atmosphere are doubled called the equilibrium of climate sensitivity.

The study found that based on the latest generation of climate models, the equilibrium of climate sensitivity is likely between 1.9 and 3.4 ° C.

Co-author Mark Williamson, of Exeter’s Global Systems Institute, added: “Global warming since 1970 also provides even better guidance on the rate of climate change in the future.

“We find a likely range for the ‘Transient Climate Response’ of 1.3-2.1 ° C, or we use the latest models as the previous generation models.”

The new study is just one piece of the puzzle.

A recent assessment paper found that low estimates of climate sensitivity can be ruled out because, in general, they are inconsistent with climate change in the Earth’s past.

Co-author Professor Peter Cox explains the significance of these findings: “It is good to see that research is now converging on a range of equilibrium climate sensitivities, and that both high and low values ​​can be excluded.

“For more than forty years, climate scientists have been trying to address this quantity and it seems we are finally getting close.”