We can now rapidly and reliably link heatwaves, droughts and hurricanes to human-induced global warming, says climate scientist Friederike Otto. The science could soon be used as evidence in legal cases brought against fossil fuel companies
22 July 2020
THE bush fires that engulfed parts of Australia earlier this year were nothing short of apocalyptic. More recently, a record-breaking heatwave has hit Siberia, causing a thaw in the permafrost that contributed to one of Russia’s worst ever oil spills. But were these disasters caused by climate change?
For a long time, scientists have said that we can’t pin any single extreme weather event on our greenhouse gas emissions. That is still true, but in recent years, researchers have become far better at estimating how much more probable any given “natural” disaster was made by human-caused global warming.
This work is called extreme event attribution, and it involves comparisons between real observations of weather events and computer simulations of a world with and without the roughly 1°C hike in temperatures caused by humanity so far. Run the simulations thousands of times and you can calculate the odds of the event occurring in both scenarios. So you can say, for example, that the drought conditions that were responsible for the Australian bush fires were made at least 30 per cent more likely by climate change. Or that human-induced global warming made the rise in temperatures that have been seen in Siberia over the past few months at least 600 times more likely.
Friederike Otto at the University of Oxford, who led the team behind the rapid-response studies that made both of these estimations, is at the vanguard of the field. As co-founder of the World Weather Attribution project, she has been pivotal in recent work that has significantly sped up the process.
Attribution already occurs in a matter …