中国气候变化信息网 China Climate Change Info-Net

(2017-09-27)The scorching temperatures across Europe’s Mediterranean nations this summer were made at least 10 times more likely by climate change, according to scientists.

Furthermore, without action to tackle global warming, such summer heatwaves with temperatures soaring over 40C will become normal by 2050.

The new analysis by the World Weather Attribution (WWA) group also analysed the particular “Lucifer” heatwave which struck south-east France, Italy and Croatia in early August and found it was made at least four times more likely by human-caused climate change.

The Lucifer heatwave saw temperatures fail to drop below 30C for three days and nights in the hottest spots, and was linked to a 15% surge in emergency hospital admissions in Italy. Prolonged heat is known to be very dangerous to health and a severe heatwave in Europe in 2003 was linked to 75,000 deaths by subsequent analysis.

“Summers keep getting hotter,” said Friederike Otto at the University of Oxford, UK, also part of WWA. “Heatwaves are far more intense than when my parents were growing up in the 1950s. If we do nothing to reduce our greenhouse gas emissions, the kind of extreme heat we saw this past summer will be the norm when my young son is a grown man.”

The fast-growing science of climate change attribution tackles the question of what impact global warming is having on extreme weather and the people it affects. No event can be said to be caused by climate change because random extremes occur naturally. But by comparing extremes with historical measurements and computer models of a climate unaltered by carbon emissions, researchers can show how global warming is already heavily loading the dice of dangerous weather.

In June, WWA showed the extreme heatwave that saw deadly forest fires blazing in Portugal and Spain was made 10 times more likely by global warming. In Portugal, 64 people died. Previous work has demonstrated floods in England and France – even as far back as 2000 – were made more significantly likely by climate change.

Research in Australia has shown the bleaching of the Great Barrier Reef was 175 times more likely due to greenhouse gas emissions, while the recent hot winter was made 60 times more likely.

Hurricanes are much more complex and time consuming to analyse than heatwaves and WWA is currently working on Hurricane Harvey. But scientists are clear that climate change is most likely to have made the giant storms that have ripped across the Caribbean and the US this year more destructive. This is because greater heat means more storm energy and rainfall, while rising sea level means storm surges reach further inland.

The new research analysed this summer’s heat across Spain, southern France, Italy and the Balkans. It compared the measured temperatures with four different groups of climate models in which the heating effect of the last century of carbon emissions were omitted. This showed the high level of heat in June, July and August was at least 10 times more likely than it would have been in the early 1900s.

The researchers did the same for the Lucifer heatwave, examining its three-day peak in early August. They found the intensity of such heatwaves has increased by 1C to 2C since 1950 and that overall climate change has quadrupled the change of them happening.

In June, the Guardian revealed that the UK government’s failure to update building regulations for homes, hospitals and schools could cause a tripling of heatwave deaths by 2040.

“It is critical that cities work with scientists and public health experts to develop heat action plans because such extreme heat will become the norm in the middle of the century,” said Robert Vautard, a researcher at the Laboratory of Climate and Environmental Sciences in France. “Climate change is impacting communities right now and these plans save lives.”