[BBC]
‘Stalling’ weather systems
One reason Boris has produced so much rain is that the weather system got ‘stuck’, dumping huge amounts of water over the same areas for days.
There is some evidence that the effects of climate change on the jet stream – a band of fast-flowing winds high up in the atmosphere – may make this ‘stalling’ phenomenon more common. But this is still up for debate.
Even if we don’t get more ‘stalled’ weather systems in the future, climate change means that any that do get stuck can carry more moisture and therefore be potentially disastrous.
“These weather patterns occurred in a warmer climate because of our greenhouse gas emissions, [so] the intensity and volume of rainfall was larger than it would have otherwise been,” explains Richard Allan, professor in climate science at the University of Reading.
Weather forecasts are continually improving, and in this case the huge levels of rainfall that triggered the floods were forecast several days in advance.
That meant flood preparations could be put in place.
That’s partly why the death toll was not as bad as previous major flooding in 1997 and 2002, even though the recent rain was heavier in many places and the floods covered a larger area.
“There has been a lot of money spent after the previous two floods to [install and update] the flood defences,” explains Mirek Trnka of the Global Change Research Institute in the Czech Republic, one of the countries most affected by the flooding.
In the city of Brno, for example, where Prof Trnka is based, not all of the flood defences had been completed, but the advanced warning allowed authorities to strengthen areas where there was still work to be done.
Not everywhere in Europe has been as fortunate. The EU has pledged €10bn (£8.3bn) in emergency repairs to help affected areas.
“It shows just how expensive climate change is,” says Dr Otto.
Over recent decades, improved flood protection has largely shielded communities from increased impacts.
But there are concerns that rising temperatures – and so ever increasing extreme rainfall – could make them ineffective.
“The [severity of the] flood events is going to increase considerably in the future, so if you keep the flood protections at the same level as they are today, the impacts may become unbearable for societies in Europe,” explains Francesco Dottori of IUSS in Pavia, Italy.
There is of course a clear way to stop these rainfall events from getting ever worse – cutting emissions of planet-warming gases such as carbon dioxide.
“Our simulations show that if you are able to keep future global warming below 1.5C, which is one of the targets of the Paris agreement, then future flood damage will be cut by half compared to the [business as usual] scenario,” Dr Dottori adds.
Otherwise, we know what will happen to these events in the future, Prof Allan says.
“The intensity of rainfall and these weather events will only get worse.”
Map by Muskeen Liddar.
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Publish date : 2024-09-24 20:06:00
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