Summers and heatwaves in Europe will be even more sweltering than feared. The regional climate models relied on by planners greatly underestimate summer heat because they don’t factor in more intense sunshine due to falling air pollution, a study has shown.

“If models don’t take air pollution changes into account, they will underestimate the intensity of future heatwaves even more than they underestimate mean summer warming,” says Dominik Schumacher at ETH Zürich in Switzerland. “It’s problematic because a lot of European countries strongly rely on these simulations to plan for the future.”

Running global climate models requires a lot of expensive computer time, so researchers often look only at smaller regions, allowing them to run more detailed models. These higher-resolution regional models are typically relied on by governments, as their projections for specific locations are supposed to be more accurate than global models.

“The regional models are used in many countries to inform future changes, so really should do a good job capturing the observed warming,” says Schumacher.

But when he and his colleagues compared the observed summer warming in Europe between 1980 and 2022 with the projections of global and regional climate models, they found the regional models underestimated the actual warming by more than 1°C, on average. The global models did better, only underestimating by an average of around 0.5°C.

“The regional models are used in many countries to inform future changes, so really should do a good job capturing the observed warming,” says Schumacher.

But when he and his colleagues compared the observed summer warming in Europe between 1980 and 2022 with the projections of global and regional climate models, they found the regional models underestimated the actual warming by more than 1°C, on average. The global models did better, only underestimating by an average of around 0.5°C.

“The regional models are used in many countries to inform future changes, so really should do a good job capturing the observed warming,” says Schumacher.

But when he and his colleagues compared the observed summer warming in Europe between 1980 and 2022 with the projections of global and regional climate models, they found the regional models underestimated the actual warming by more than 1°C, on average. The global models did better, only underestimating by an average of around 0.5°C.

Reference: European Geosciences Union meeting 2024 DOI: 10.5194/egusphere-egu24-18153

Original: https://www.newscientist.com/article/2428124-european-summers-will-be-hotter-than-predicted-because-of-cleaner-air/