827. Climate Change Significantly Increased the Occurrence of Extreme Heatwaves in July 2023

Following the record-breaking heat of June 2023, this July has seen new record high temperatures across the globe. On July 16th, temperatures in Death Valley, USA, and northwestern China surpassed 50℃.

On July 25th, the World Weather Attribution (WWA), an organization that analyzes extreme events and their relationship to climate change, reported that extreme heatwaves observed in the Northern Hemisphere in July 2023 are more likely to occur due to climate change.

In recent years, reports such as the IPCC have predicted the increased frequency of heat waves due to human-caused global warming. The WWA states that the current extreme heat waves are no longer rare events under today's climate conditions. They could occur every 15 years in the United States and Mexico, every 10 years in southern Europe, and every 5 years in China.

Conversely, without human-induced climate change, the ongoing heatwaves would have been considered extremely rare events. According to the WWA, the intensity of the heatwaves observed in July 2023 would have occurred only once every 250 years in China, and would have been virtually nonexistent in the United States, Mexico, and southern Europe without human-induced warming from the burning of fossil fuels.

In the future, as global warming continues, such extreme heatwaves are expected to become more common. The WWA warns that in a world where temperatures have risen by 2°C above pre-industrial levels, heatwaves of increased intensity and duration could occur every 2 to 5 years. They call for urgent reductions in fossil fuel use and emphasize the need to accelerate action plans to overcome vulnerability to heatwaves, taking into account the trends of climate change, aging populations and urbanization.

Contributor: IIYAMA Miyuki (Information Program)