Climate change feeds record summer heat, killing thousands

The last three summers have been the three warmest ever recorded

By Andrea Thompson Edited by Dean Visser

The summers of the northern hemisphere of 2023, 2024 and 2025 were the three warmest ever recorded, the European Union and the United States climate agencies announced. This record heat of summer was mainly driven by climate change of human origin, which not only increased the average global temperatures, but also fueled waves of more deadly heat. A new study published on Wednesday concludes that climate change has probably tripled the number of heat -related deaths in European cities this summer.

“Many of them [people] Would not have died without climate change, “said the co-author of the Friederike Otto study, climatologist at Imperial College in London, during a press conference on the conclusion.

The period from June to August 2025 was the hottest third ever recorded, with a global average temperature of 0.47 degree Celsius (0.85 degree fahrenheit) above the average of 1991-2000, according to the Copernicus Climate Change Service of the European Union (C3S). (The same period in 2023 was the hottest second, and that in 2024 remained in the first place.) The National Oceanic and Atmospheric American Administration also ranked the last summer of the northern hemisphere as the third warmer of the agency’s 176 -year record and measured it at 1.02 degrees C (1.84 degrees F) warmer than the average of the 20th century.

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According to the NOAA, the current year to date is to date as the hottest second ever recorded, behind 2024. The first part of 2025 presented a weak Niña, a climate model which includes cooler waters than the average in the tropical Pacific and tends to cool global temperatures. But the years of Niña in recent decades have been even warmer than the years of the 20th century which fell under El Niño, a model that tends to increase global temperatures.

The year 2024 was the first recorded to have an average temperature greater than 1.5 degrees C (2.7 degrees f) above the pre-industrial era. By virtue of the Paris climate agreement (from which President Donald Trump decided again to withdraw the United States), the countries have agreed to try to limit warming less than 1.5 degrees C and “well below” of two degrees C (3.6 degrees F). But although reaching the milestone of 1.5 for a year is extremely worrying and a marker of the measure in which the world is to achieve these objectives, this does not mean that the climatic threshold of Paris has been violated; The agreement examines global average temperatures over many years. On this broader time scale, the world is approximately 1.2 to 1.3 degrees C (2.2 to 2.3 degrees f) above the pre-industrial period due to greenhouse gases that have spilled into the atmosphere since that time.

Last October, the World Meteorological Organization (WMO) confirmed that the average carbon dioxide levels, the main greenhouse gas, had reached a record level of 420 parts per million (PPM) in 2023.₂ The levels of the pre -industrial period were around 280 ppm.

The hottest 10 years ever recorded have taken place in the last decade, according to C3S, Noaa and NASA data.

Of course, no one lives on average – they experience time locally and daily. But the effects of climate change are also clear. The new study, led by researchers from the Imperial College of London and the London School of Hygiene & Tropical Medicine, has combined climate models with temperature and epidemiological data data to estimate the number of deaths related to additional heat caused in Europe in last summer. They found that in 854 urban areas they examined, 68% of the 24,400 estimated thermal deaths were attributable to climate change.

And this number is probably conservative because it only covers around 30% of the European population and does not include other regions. “The details will vary wherever you look in the world, but the basic point of these studies will always be the same: that we warm the world through our fossil combustible and other activities and other activities and that it kills people,” said Clear Barnes, climate researcher at the Imperial College in London, during the press conference. “This is what it comes down to.”

And the proportion of thermal deaths attributable to climate change rises, says Otto.

In the United States, where the heat is the deadliest killer of time, residents have gone from the average of two heat waves each summer in the 1960s to more than six today. These heat waves have also extended from an average of three days to four – and the heat waves season lasts much longer, extending from more than 20 days in the 1960s to more than 70 now.

This trend should persist while society continues to burn fossil fuels: a study in 2021 Science have found that even under the current promises to reduce greenhouse gases in countries, children born in 2020 will experience seven times more heat waves during their lives than people born in 1960. These future waves will also last longer and have ever higher temperatures than those of today.

Without a more concerted action on the part of governments and businesses to slow down emissions, it is only a matter of time before these summers with record is pushed down the list, which means that the record heat of today seems relatively cool in the coming decades.

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