気候変動：主要な炭素排出源が熱波の強度と発生確率に影響を及ぼしている

A quarter of heatwave events from 2000 to 2023 would have been near impossible without anthropogenic climate change, a paper in Nature suggests. The paper also indicates that major carbon emitters are responsible for around 50% of the increase in intensity of these events.

The frequency and intensity of extreme weather events are reported to be influenced by human-induced warming. The contribution of these climate changes to specific events has been investigated but what impact these changes may have made to a series of events is unclear. Additionally, the contributions of emitters to climate changes are underexplored.

Using data from an international disaster database on 213 heatwaves from 2000 to 2023, Yann Quilcaille and colleagues expanded a well-established event-based framework to assess how much anthropogenic climate change had influenced these events. They suggest that without climate change, a quarter of these heatwave events would have been nearly impossible. The median estimates indicate that compared to 1850–1900, heatwaves became 20 times more likely between 2000 and 2009 and 200 times more likely from 2010 to 2019 as a result of climate change. They note that the median of the events also shows that the intensity of heatwaves increased by 1.4 °C from 2000 to 2009, 1.7 °C during 2010 to 2019 and 2.2 °C from 2020 to 2023 as a result of climate change.

Using data from the 180 biggest carbon majors (businesses with a particularly high emission profile), Quilcaille and colleagues examined the role their emissions had in increasing the frequency and intensity of the events. They indicate the emissions from the carbon majors contributed 50% of the increase in heatwave intensity since 1850–1900. The authors suggest that the individual emissions from each carbon major may have contributed to the occurrence of 16 to 53 heatwaves (that previously would have been virtually impossible in a pre-industrial climate).

The authors conclude that their findings show the influence human-induced climate change has had on the likelihood and frequency of extreme events and highlights the role emissions have in their occurrence. They note that their framework could be adapted for other hazards and has implications for climate policy.