“Today, another spell of sunshine, thanks to that ongoing area of high pressure. And we can confirm that last week’s flooding was made six times more likely because of climate change.” Not your usual weather report – but this could be the reality for Europeans within two years.
The climate arm of the European Union’s Earth observation programme, Copernicus, is that could lead to weather agencies in 2021 being provided with “timely and reliable information” on extreme weather events and how they are related, or not, to human-made climate change. German and French weather agencies are also looking to develop their own services.
While no single scorching heatwave or deluge can be said to be caused by global warming, the field of climate change attribution has matured rapidly in recent years. The approach involves comparing real weather observations with computer models of a world without warming caused by human activity, to express how much more likely an extreme weather event was made by global warming. The Seine-swelling Paris floods of 2016, for example, .
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Now attribution is preparing to step from the research community into the wider world. “It’s good this is now happening,” says the UK Met Office’s Peter Stott. “People of course ask the question with extreme weather events, of how they are linked to climate change.”
Stott says extreme events bring home for us how vulnerable people are to the weather, pointing to the . It is important to know if vulnerability is due to natural variability or linked to a warming world. “Is this just bad luck or is climate change adding to the risks? That’s where the attribution comes in,” he says.
German weather agency DWD is building its own climate attribution system, which it hopes will by ready by late next year. “Attribution can provide answers here. With the knowledge, the public or politicians get a better picture of the effects of climate change,” says Frank Kreienkamp of DWD.
Climate attribution studies used to be carried out well after the event, but the process is speeding up. The three main stages of attribution – defining the event, crunching data and analysing the results – can today be slimmed down to one or two weeks, says Dick Dee of the Copernicus Climate Change Service, part of the Copernicus programme.
Only so much of the work can be automated, with most of the time taken up by pinning down the nature of the event, interpreting the results and checking for mistakes. “The bottleneck is humans,” says Friederike Otto at the University of Oxford. But with enough expertise and a clear procedure, within two years we could see the turnaround squeezed to two days after an event, she says.
Today, attribution studies are good at pinpointing the likelihood of climate change influencing extreme heat and heavy rainfall. But the models and methods aren’t yet sufficiently tested to do quick turnarounds for wind storms and complex droughts. Other events, such as hail, are even further out and will need more research.
Taking attribution out of the research world and making it a routine service poses challenges beyond the studies themselves. One is that definitions of extreme weather events will need to be standardised to avoid confusing the public.
Last year’s summer heatwave in northern Europe, for example, was found by Otto and her colleagues to have been made , while a reported it to have been 30 times more likely. “Neither of these studies are wrong, but they all define what a heatwave is in very different ways, thus providing very different key messages,” says Otto.
There is also the question of how best to communicate the messages, something the Copernicus trial will focus on. “As soon as you start talking about probability and statistics, it starts getting difficult,” says Dee. Even talking in a weather forecast about an 80 per cent chance of rain is very confusing to most people, he says.
The Copernicus prototype should be up and running in early 2020. Dee says weather agencies could be using attribution of extreme weather events from 2021, provided a second stage of funding gets the green light. Weather forecasters do seem to be good messengers for improving public understanding of climate change. has found people – even those doubtful that human-made climate change is real – are receptive to forecasters talking about global warming.
Stott says that, for the Met Office, there are still “big challenges”, particularly around certain types of weather event, and a roll-out of climate attribution on the agency’s forecasts and communications will depend on the public’s appetite. But, he says: “I think it is a question of when, not if.”
