Global warming: each heat wave reinforced by climate change: experts

All heat waves today bear the unmistakable and measurable footprint of global warming, top experts in quantifying the impact of climate change on extreme weather said on Wednesday.

All heat waves today bear the undeniable and measurable footprint of global warming, top experts in quantifying the impact of climate change on extreme weather said on Wednesday.

The burning of fossil fuels and the destruction of forests have released enough greenhouse gases into the atmosphere to also increase the frequency and intensity of many floods, droughts, wildfires and tropical storms, they detailed in a report on the state of the science.

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“There is no doubt that climate change is a huge game-changer when it comes to extreme heat,” Friederike Otto, a scientist at the Grantham Institute at Imperial College London, told AFP.

Extreme heat waves such as the heat wave that hit South Asia in March and April are already the deadliest extreme events, she added.

“Every heat wave around the world is now made stronger and more likely to occur due to human-induced climate change,” Otto and co-author Ben Clarke from the University of Oxford said in the report. , presented as a backgrounder for the media. .

Evidence of the impact of global warming on extreme weather events has been accumulating for decades, but only recently has it been possible to answer the most obvious questions: to what extent a particular event has- was it caused by climate change?

Most scientists could tell before that an unusually severe hurricane, flood, or heat wave was consistent with general predictions of how global warming would eventually influence the weather.

The news media, meanwhile, has sometimes completely ignored climate change or, at the other extreme, mistakenly attributed climate catastrophe entirely to rising temperatures.

With more data and better tools, however, Otto and other pioneers in a field known as event attribution science were able to calculate – sometimes in near real time – how much a particular storm or heat wave has become more likely or intense due to global warming.

Evidence in the courtroom

Otto and his colleagues from the World Weather Attribution (WWA) consortium, for example, concluded that the heat wave that gripped western North America last June – pushing temperatures in Canada to a record high of 49.6°C (121°F) – would have been “virtually impossible” without human-induced climate change.

The heat wave that ravaged India and Pakistan last month is still under investigation, Otto told AFP, but the bigger picture is starkly clear.

“What we are seeing now in terms of extreme heat will be completely normal, if not cool, in a 2-3 degree Celsius world,” she said, referring to average global temperatures above pre-industrial levels.

The world has warmed by almost 1.2°C so far.

The increase made record rainfall and flooding last July in Germany and Belgium that killed more than 200 people up to nine times more likely, the WWA found.

But global warming isn’t always to blame.

A two-year drought in southern Madagascar resulting in near-famine conditions attributed by the UN to climate change was actually the product of natural weather variability, experts have reported.

Quantifying the impact of global warming on extreme weather events using peer-reviewed methods has real policy implications.

Attribution studies, for example, have been used as evidence in historic climate litigation in the United States, Australia and Europe.

In a case set to resume later this month, Saul Luciano Lliuya v RWE AG, a Peruvian farmer is suing the German energy giant for the costs of preventing harmful flooding from a glacial lake destabilized by climate change.

A scientific assessment filed in evidence has concluded that man-made global warming is directly responsible for creating a ‘critical threat’ of a devastating explosion, putting a city of some 120,000 people on the path to potential flooding .

Teresa H. Sadler