If the heat records of recent years weren’t enough, a new study warns that what’s already bad could get worse than expected. According to research published in the Proceedings of the National Academy of Sciences (PNAS), one of the most prestigious scientific journals in the world, heat waves in the coming years are expected to be more severe and frequent than those projected by climate models.
Unseasonably hot: firefighters battle vegetation fires on the Harlem River, in Manhattan. New York faces anomalous drought and heat conditions in November for the autumn in the Northern Hemisphere — Photo: AFP
The study authors say the models underestimated the intensity of heat extremes, especially in the Amazon, much of South America, including Brazil, Australia, northern Canada and northern Europe.
” Projections of extremes are quite conservative in relation to heat. We need to prepare,” said the study’s lead author, Kai Kornhuber, from the International Institute for Applied Systems Analysis, in Austria, to the British magazine New Scientist.
Kornhuber led a reanalysis of leading climate models. Scientists have seen that if the frequency of daily maximum temperatures at a location over a given period of time is graphed, the distribution will show a classic bell-shaped curve, with most temperatures concentrated around the mean and some extremes. distant. If the average temperature increases over time, the curve will move sideways.
However, global warming causes extreme heat to be more frequent and intense than would be expected from an increase in average temperature alone. This flattens and widens the bell curve. And it shows that extreme heat persists.
Kornhuber warns that unprecedented heat waves could occur throughout the year. He and his team analyzed the planet’s warming curves from 1958 and 2022. They then simulated this same period with the most recent climate models. Then, they compared the recorded trends with the simulated ones.
Overall, the models did well and captured the increase in heat extremes. However, in some parts of the planet the heat extremes were much worse than the simulations indicated.
Kornhuber explains that the models are good, but they still have difficulty simulating the full complexity of extreme events. He says one of the causes of so much heat is that climate change has made so-called atmospheric blockages more common and longer-lasting. These are hot domes, like the ones that in 2023 and this year turned much of the Central-West, Amazon and Southeast of Brazil into a furnace.
Another factor that the models also do not adequately consider is the low level of soil and vegetation moisture, which generates a vicious cycle. The lack of rain and intense heat dry out plants and soil and, as a result, there is less cooling through evaporation. Less moisture is returned to the atmosphere, making it difficult for rain clouds to form and thus perpetuating the dry, hot condition.
Kornhuber says that models still cannot capture the full complexity of local phenomena that contribute to intensifying extremes.
