August and September mark the end of winter in the Southern Hemisphere, but a large swath of South America spent much of that period in deadly heat that felt much more like summer. Late in this past winter, millions of people in Brazil, Bolivia, Argentina and Paraguay experienced temperatures that exceeded 40 degrees Celsius —an event that was made 100 times more likely, and significantly hotter, by climate change, according to a new rapid analysis.
A tendency toward more extreme heat events and fewer extreme cold ones is a hallmark of the changing climate as humans continue to burn fossil fuels and add to the heat-trapping greenhouse gases in the atmosphere. In parts of South America, the whole winter period was punctuated by intense heat dome events, in which an atmospheric pattern that ushers in extreme heat becomes entrenched.
The researchers found climate change made the recent South American event at least 100 times more likely and from 1.4 to 4.3 degrees C hotter. Such an event would be expected about every 30 years in today’s climate. Other recent WWA research found climate change exacerbated heat waves in China, North America and Europe earlier in the Northern Hemisphere’s just concluded summer. The team even concluded that the latter two heat waves would have been virtually impossible without the influence of climate change.