This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Recent heat waves in Europe have been intensified by the greenhouse gases emitted since nations committed to limiting global warming under the 2015 Paris Agreement, according to a Sep. 22 study published in Geophysical Research Letters. "We found strong evidence that if Europe's heat wave in the summer of 2025 had occurred without the emissions since 2015, it very likely would have been cooler," said lead author Jared Trok, a doctoral student in Earth system science at the Stanford Doerr School of Sustainability.
"That result is not unique to the 2025 heat wave, but also true for Europe's hottest week in every individual year since at least 2021." Scientists have long studied whether the burning of fossil fuels since the Industrial Revolution in the mid-19th century has contributed to changes in global average temperatures and other aspects of Earth's climate. Over the past two decades, researchers have developed methods to study how historical emissions have affected heat waves, hurricanes, droughts, wildfires and other extreme weather events. This new study builds on that research by using generative AI trained on climate models to quantify whether subsets of all human-caused emissions have influenced specific weather events in recent years.
The findings highlight the need to prepare for more extreme weather, even if policy goals for reducing greenhouse gas emissions are successful. Under the 2015 Paris Agreement, nearly 200 countries pledged to limit global warming to well below 2°C above preindustrial levels, while pursuing efforts to limit warming to 1.5°C, or 2.7°F. Global warming is already approaching the 1.5°C threshold, and stabilizing the global temperature will require reducing emissions to "net-zero," the point at which greenhouse gases released into the atmosphere are balanced by natural mechanisms or advanced technologies.
"Even in the most optimistic timelines for reducing emissions, there will still be more emissions in the future than there have been in the last decade since the Paris Agreement," said co-author Noah Diffenbaugh, the William Wrigley Professor and Kimmelman Family Senior Fellow in the Stanford Doerr School of Sustainability. "This study highlights that we can expect the kinds of extreme heat waves we've been experiencing recently to intensify even more in the coming years." As annual global emissions drive up carbon dioxide levels in the atmosphere, heat waves are reaching new extremes. Scorching temperatures killed several thousand people across Europe in 2025, resulting in the hottest June observed in the region until heat waves broke that record in 2026.
Almost one-fifth of all carbon dioxide emissions from burning fossil fuels have been emitted in the decade since the Paris Agreement was adopted. Most of those emissions have come from burning oil, natural gas and coal. The new study results indicate there is more than a 99% chance that emissions during this decade intensified Europe's deadly June 2025 heat wave.
The researchers estimated the emissions increased average daily temperatures in some regions by roughly a third of a °C, or just over half a °F. "That third of a degree temperature change may seem small," said Trok, "but a large body of literature shows that small changes in temperature can have meaningful impacts on the damages caused by those extreme weather events." For example, previous research by Trok, Diffenbaugh and colleagues has found that a small climb in temperature can disproportionately increase the risk of heat-related deaths in Europe. Another study shows that changes in daily temperature have disproportionate impacts on electricity demand, mortality rates, agricultural yields, labor productivity and other sectors across the United States.
Extract — continue reading at the source.
