All heatwaves today bear the unmistakable and measurable fingerprints of global warming, top experts on quantifying the impact of climate change on extreme weather said Wednesday.
Burning fossil fuels and the destruction of forests have released greenhouse gases into the atmosphere that have increased the intensity of floods, fires, and tropical storms.
Friederike Otto, a scientist at Imperial College London's Grantham Institute, told Agence France-Presse that climate change is a huge game-changer when it comes to extreme heat.
The most deadly of extreme events are the hot spells that hit South Asia in March and April.
Otto and co-author Ben Clarke of the University of Oxford said in the report that every heatwave in the world is now made stronger and more likely to happen because of human-caused climate change.
Evidence of global warming's impact on extreme weather has been mounting for decades, but only recently has it been possible to answer the most obvious of questions: What extent was a particular event caused by climate change?
The most scientists have been able to say is that the weather was consistent with predictions of how global warming would affect it.
News media sometimes left climate change out of the picture altogether or wrongly attributed a weather disaster to rising temperatures.
Otto and other pioneers of a field known as event attribution science have been able to calculate how much more likely a storm is due to global warming.
Otto and colleagues in the World Weather Attribution (WWA) consortium concluded that the heatwave that gripped western North America last June sent temperatures in Canada to a record high.
Otto told Agence France-Presse that a heatwave that scorched India and Pakistan last month is still under review.
She said that average global temperatures above preindustrial levels will be normal, if not cool, in a 2-degree to 3-degree Celsius world.
The world has warmed 1.2C so far.
More than 200 people died in Germany and Belgium in July of last year because of record-setting rain and flooding, according to the WWA.
Sometimes global warming is not to blame.
Natural variability in the weather is what caused the two-year dry spell in southern Madagascar that the UN attributed to climate change.
Peer-reviewed methods can be used to quantify the impact of global warming on extreme weather events.
In landmark climate litigation in the United States, Australia, and Europe, Attribution studies have been used as evidence.
The case of Saul Luciano Lliuya v. RWE AG is set to resume later this month.
A scientific assessment concluded that human-caused global warming is to blame for creating a critical threat to the city of some 120,000 people.
Agence France-Presse
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