Global Heatwaves: Starting Earlier and Lasting Longer, According to a New Study
A study published in Nature Climate Change shows that heatwaves on continents are starting earlier, lasting longer, and intensifying. This evolution is altering forecast uncertainty and posing new challenges to meteorologists and decision-makers.
Heatwaves Are Starting Earlier and Developing More Quickly: What the Latest Study Reveals
Early heatwaves of the season are now appearing several days before the historical average, and the total duration of heat episodes is noticeably increasing. According to researchers, the "rapid start" of the first heat peak reflects climate disruption already evident in global atmospheric data.
What the study reveals: Lengthening and earlier heatwaves
The analysis, covering decades of satellite observations and ground records, indicates that heatwaves on Earth are starting earlier, ending later, and extending over longer seasons. In some regions, the period of extreme heat has increased by several weeks, although the exact figure remains "unconfirmed information at this stage" in the press release.
Researchers also note that the first heat episode of each year now shows a "rapid onset", meaning temperatures exceed critical thresholds in less time than before. This acceleration increases populations' exposure to health risks, such as heat strokes and exacerbations of chronic illnesses.
How: Research method and data used
To extract these trends, the team combined Copernicus satellite data with ECMWF archives and Météo France time series. A predictive model based on a neural network was trained using machine learning, integrating variables such as soil moisture, cloud cover, and radiative heat fluxes.
The training process used advanced architectures like GraphCast and Pangu-Weather, allowing for the capture of complex interactions between atmospheric data points. Forecast uncertainty was quantified at each stage to distinguish natural variations from climate change-induced changes.
Scientific explanation of the phenomenon
The observed disruption originates from the continuous increase in greenhouse gas concentrations, primarily carbon dioxide and methane, since the start of the industrial era. These gases retain an increasing fraction of infrared radiation emitted by Earth, raising the average temperature of the atmosphere and oceans. Two key mechanisms explain the early onset and rapidity of first heatwaves:
