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Issued at 11:12
Paris (AFP) – Top experts in quantifying the effects of climate change on extreme weather pointed out Wednesday that all heatwaves bear the unmistakable fingerprint of global warming.
They explained in a state of science report that the destruction of forests and burning fossil fuels has resulted in enough greenhouse gases being released into the atmosphere to increase the frequency and intensity many floods, droughts and tropical storms.
Friederike Otto, a Grantham Institute scientist at Imperial College London, stated that “there is no doubt” that climate change has the potential to transform extreme heat.
Extreme heat spells like the one that hit South Asia in March/April are already the most deadly extreme events, she stated.
“Every heatwave around the world is now stronger and more likely because of human climate change,” Otto and Ben Clarke of Oxford stated in the report, which was presented as a briefing document for the media.
Although evidence of global warming’s effect on extreme weather has been mounting over the past decades, it has only been recently that it has been possible to answer one of the most important questions: To what extent was this particular event caused or exacerbated by climate change?
Scientists have been able to say that an unusually severe hurricane or flood, or heatwave, was consistent with general predictions about how global warming would affect weather.
In the meantime, news media sometimes ignored climate change entirely or incorrectly attributed rising temperatures to a weather disaster.
Otto and other pioneers in event attribution science were able to calculate, sometimes in near realtime, how likely a storm or hot spell is due to global warming.
Courtroom evidence
Otto and others from the World Weather Attribution Consortium (WWA) concluded, for example that the heatwave that swept across western North America last summer — sending temperatures to record 49.6 C (121 F), in Canada — would have been “virtually impracticable” without human-induced global warming.
Otto said that while the heatwave that scorched India last month and Pakistan is still being investigated by AFP, the bigger picture is alarmingly clear.
“What we see in terms of extreme heat right now will be very typical, if not cooler, in a 2° to 3° Celsius world,” she said. She was referring to global temperatures that are higher than preindustrial levels.
The world has warmed up to 1.2C so far.
This increase led to record-setting rainfall and flooding in Germany, Belgium and Germany last July that left more 200 people dead. It was nine times more likely than usual, according to the WWA.
Global warming is not always to blame.
Experts have reported that the two-year drought in southern Madagascar that caused near famine conditions was actually caused by natural variability of the weather.
Real-world policy implications result from quantifying the impact of global heating on extreme weather events with peer-reviewed methods.
In landmark climate litigation in the United States, Australia, and Europe, attribution studies were used as evidence.
One case will resume later in the month: Saul Luciano Lliuya, a Peruvian farmer, v. RWE AG. The lawsuit seeks damages from the German energy giant for failing to prevent flooding from a glacial lake that has been destabilised by climate changes.
A scientific analysis that was presented into evidence has concluded that human-caused climate change is directly responsible in creating a “critical risk” of a devastating eruption, putting 120,000 people in danger of flooding.
© 2022 AFP
