Amid these rising averages, a new and puzzling trend has emerged: isolated regions experiencing extreme and unpredictable heat waves that defy existing climate models. A groundbreaking study has identified and mapped these "hotspots," which appear on every continent except Antarctica. These intense heat waves have led to widespread devastation, including tens of thousands of deaths, widespread crop failures, and catastrophic wildfires.
"The large and unexpected margins by which recent regional-scale extremes have broken earlier records have raised questions about the degree to which climate models can provide adequate estimates of relations between global mean temperature changes and regional climate risks," the study noted.
Lead author Kai Kornhuber of the Lamont-Doherty Earth Observatory and the International Institute for Applied Systems Analysis described these areas as "temporary hothouses," where extreme heat accelerates beyond predictions. The research was recently published in Proceedings of the National Academy of Sciences.
A World Map of Intensifying Extremes
The study examined data from the last 65 years, identifying regions where extreme heat is outpacing moderate temperature increases. These include populous areas like central China, Japan, Korea, and the Arabian Peninsula, as well as parts of Australia, Africa, Canada, Greenland, South America, and Siberia. Northwestern Europe has emerged as the most consistent and intense hotspot, with heat waves contributing to 60,000 deaths in 2022 and 47,000 in 2023.
"In recent years, the hottest days of the year are warming twice as fast as average summer temperatures," the study found. Europe's vulnerability stems partly from limited air conditioning infrastructure, historically deemed unnecessary in the region.
Causes of Extreme Heat
The study attributed some heat waves to climate-change-related factors, while others were linked to atmospheric anomalies like jet stream disruptions. For instance, the deadly 2021 Pacific Northwest heat wave resulted from a combination of jet stream instability, long-term vegetation drying, and atmospheric waves transporting heat from the Pacific Ocean.
This event included record-breaking temperatures of 49.6C (121.3 F) in Lytton, British Columbia, just before the town was consumed by a wildfire. Hundreds died in Oregon and Washington from heat stroke and related conditions.
A Growing Crisis
Excessive heat is now the leading weather-related cause of death in the United States, with over 2,300 fatalities reported in 2023. Researchers are calling for heat waves to be named, akin to hurricanes, to improve public awareness and policy responses.
Kornhuber warned, "Due to their unprecedented nature, these heat waves are usually linked to very severe health impacts, and can be disastrous for agriculture, vegetation and infrastructure. We're not built for them, and we might not be able to adapt fast enough."
The study highlights the urgent need for improved climate models to anticipate and address these emerging patterns. Coauthors include Richard Seager and Mingfang Ting of the Lamont-Doherty Earth Observatory and H.J. Schellnhuber of the International Institute for Applied Systems Analysis.
Research Report:Global emergence of regional heatwave hotspots outpaces climate model simulations
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Lamont-Doherty Earth Observatory.
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