Climate change role clear in many extreme events but social factors also key, study finds

Climate change is to blame for the majority of the heatwaves being recorded around the planet but the relation to other extreme events and their impacts on society is less clear, according to a study.

They say that in the case of heatwaves, the role of climate change is unequivocal, and that the average and extreme heat levels in every continent across the globe are increasing specifically because of human-caused climate change.

A heatwave with a one in 50 chance of happening in pre-industrial times is now almost five times more likely to happen and will be 1.2C hotter, according to an IPCC report. In the past 20 years there have been 157,000 deaths from 34 heatwaves, according to data from the EMDAT disaster database. Yet the impact of human-induced climate change on heatwaves and the repercussions are still largely underestimated.

Most people died from pre-existing conditions suddenly becoming acute, Otto said, and this often did not show up in data. Wildfires were also one of the big climate impacts not talked about enough, Otto said.

For other events such as droughts, floods and tropical cyclones, there is a more nuanced link to climate change. For example, there are some regions of the world where droughts are becoming worse because of human-caused climate change, such as southern Africa, Otto notes, while in other droughts the climate change signal is either not there or very small.

Much of the problem in figuring out exactly to what extent climate change was responsible for the impact of extreme weather events, Otto said, lay in the lack of reliable data around the globe.

There is not enough information coming from lower- and middle-income countries, although these are the places more likely to be at risk of the repercussions of human-induced climate change.