News Desk Scientists identify a self-reinforcing interaction between high temperatures, drying soils and atmospheric pressure that could make the world’s most severe heat waves even more dangerous.
Climate change may be making the most extreme heat waves even hotter than previously understood, with a new study finding that an interaction between temperature, soil moisture and atmospheric pressure can amplify heat by as much as 10%.
The study, published in Science Advances, identifies a self-reinforcing process in which rising temperatures, drying soils and high-pressure weather systems work together to push temperatures even higher.
Researchers from the Potsdam Institute for Climate Impact Research (PIK) and the International Institute for Applied Systems Analysis (IIASA) led the study, with PIK scientist Yinglin Tian as lead author.
The findings suggest that the most intense heat waves are not simply the result of prolonged high temperatures. Under certain conditions, several atmospheric and land-surface processes begin reinforcing one another, producing temperatures that exceed what would otherwise be expected.
Three factors drive temperatures higher
The researchers identified three interacting factors behind the phenomenon: extreme heat, declining soil moisture and high atmospheric pressure.
High-pressure systems allow more solar radiation to reach the Earth’s surface, heating the land. As temperatures rise, soil gradually loses moisture. With less water available, the ground becomes less capable of cooling through evaporation, allowing more heat to accumulate at the surface.
These processes can create a feedback loop. Higher temperatures dry out the soil, while increasingly dry soil contributes to further warming.
The relationship between heat and soil moisture has long been recognized by climate scientists. But the new research suggests that, during the most extreme heat events, atmospheric pressure adds another dimension to the process.
“The two-way relationship between rising temperatures and drying soils has been understood for a while and is already factored into what we expect from a typical extreme heat event,” Tian said.
However, the researchers found that once temperatures cross a certain threshold, all three factors begin reinforcing one another, intensifying the heat.
“When we look at these mega heat waves that have been significantly outstripping previous temperature records, what we’re seeing is that once you reach a certain temperature, all three factors—drying soils, high pressure and extreme heat—begin to interact and drive each other further in a way that we haven’t understood before,” Tian added.
Heat-wave risks are increasing
The phenomenon has been observed in several midlatitude regions, including Europe, southern Russia, Mongolia, eastern and northwestern North America, northwestern India, western South America, central and southern Africa, and northern interior Australia.
The researchers used machine learning methods and statistical analysis to examine extreme heat events and identify the conditions under which the feedback mechanism becomes active.
Their findings also indicate that climate change is making it increasingly likely for temperatures to cross the threshold that triggers this interaction.
In Europe, for example, the feedback mechanism begins operating at around 4 Kelvin above average summer temperatures, equivalent to roughly 29 degrees Celsius.
The likelihood of temperatures in Central Europe exceeding this threshold rose from 6% between 1979 and 1983 to 23% between 2018 and 2022.
THE GROWING DANGER OF EXTREME HEAT
Extreme heat waves can become up to 10% hotter through a self-reinforcing climate feedback mechanism.
Europe: A rising heat threshold risk
The feedback mechanism begins operating at around 4 Kelvin above average summer temperatures, equivalent to roughly:
Researchers found that the likelihood of Central Europe exceeding this threshold increased substantially.
Bars use a common 0–25% scale. Figures refer to Central Europe.
The likelihood increased from 6% to 23% — nearly four times the earlier level.
United Kingdom: First time above 40°C
In 2022, the United Kingdom recorded temperatures above 40°C for the first time in its history.
The record illustrates how extreme heat can push temperatures beyond previously observed national records.
Event highlighted in the study’s discussion of record-breaking heat waves.
US Pacific Northwest: 2021 heat wave
During the 2021 summer heat wave, temperatures in the U.S. Pacific Northwest reached as much as 4.6°C above previous records.
The event demonstrated how extreme heat can produce temperature records far beyond previous historical highs.
How the heat feedback mechanism works
Click each factor to understand how the three processes reinforce one another.
High-pressure systems allow more solar radiation to reach the Earth’s surface, increasing ground temperatures.
THE BIGGER PICTURE
Climate change is increasing the likelihood of conditions that trigger self-reinforcing heat. The result could be more severe heat waves than current climate models anticipate.
Note: The 10% figure describes the amplification of the most extreme heat events attributed to the identified feedback mechanism. It does not mean all heat waves worldwide are 10% hotter.
The trend offers another explanation for why some recent heat waves have broken temperature records by unusually wide margins.
In 2022, the United Kingdom recorded temperatures above 40 degrees Celsius for the first time. A year earlier, a summer heat wave in the U.S. Pacific Northwest pushed temperatures as much as 4.6 degrees Celsius above previous records.
Such events illustrate the growing intensity of extreme heat in some parts of the world.
Climate models may underestimate the danger
The study raises concerns about how accurately current climate models capture the processes driving the most severe heat waves.
According to the researchers, the newly identified self-reinforcing interaction is not yet adequately represented in climate models used to forecast extreme heat events.
That gap could mean projections are underestimating the severity of future heat waves, particularly in regions where the feedback mechanism is likely to be triggered more frequently as the planet warms.
“If we’re right and this interaction is making the most extreme heat events even hotter, it means we could be in store for more severe future heat wave risks than what is currently expected,” said Kai Kornhuber, a study co-author from IIASA and the Max Planck Institute of Geoanthropology.
The findings add to the scientific understanding of how climate change can intensify extreme weather. They also highlight the importance of looking beyond rising air temperatures alone.
As the planet continues to warm, the combination of dry ground, persistent high pressure and extreme heat could make already dangerous heat waves even more severe.
Yinglin Tian, Three-way circulation–soil moisture–temperature feedbacks amplify the most extreme mid-latitudinal heatwaves, Science Advances (2026). DOI: 10.1126/sciadv.aeh9111. www.science.org/doi/10.1126/sciadv.aeh9111
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