New study: Climate change has made heat waves last longer, spike hotter, hurt more people
Saskia O'Donoghue
Climate change is making giant heat waves crawl slower across the globe - and they are baking more people for a longer time with higher temperatures over larger areas, a new study has found.
Since 1979, global heat waves are moving 20 per cent more slowly - meaning more people stay hot longer - and they are happening 67 per cent more often, according to a study in Friday's Science Advances.
Scientists also found the highest temperatures in the heat waves are warmer than 40 years ago and the area under a heat dome is larger.
Studies have shown heat waves worsening before - but this one is more comprehensive and concentrates heavily on not just temperature and area.
The report, co-authored by climate scientists Wei Zhang of Utah State University and Gabriel Lau of Princeton University, also focuses on how long the high heat lasts and how it travels across continents.
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What exactly did the study discover about the change in heat wave behaviour?
From 1979 to 1983, global heat waves would last eight days on average, but by 2016 to 2020 that was up to 12 days, the study found.
Eurasia was especially hit harder with longer lasting heat waves, the study said. Heat waves slowed down most in Africa, while North America and Australia saw the biggest increases in overall magnitude, which measures temperature and area.
Just like in an oven, the longer the heat lasts, the more something cooks. In this case it's peo
ple, the co-authors said.
The team conducted computer simulations showing this change was due to heat-trapping emissions that come from the burning of coal, oil and natural gas. The study found climate change's fingerprint by simulating a world without greenhouse gas emissions and concluding it could not produce the worsening heat waves observed in the last 45 years.
It also looked at the changes in weather patterns that propagate heat waves. Atmospheric waves that move weather systems along, such as the jet stream, are weakening, so they are not moving heat waves along as quickly - west to east in most but not all continents.