Climate change raised the risk of deadly floods that swept through Western Europe in July, new research confirms. As people around the world continue burning fossil fuels and pumping out greenhouse gas emissions, the threat of similar disasters grows.
Already, single-day rainfall events in the affected region are between 3 to 19 percent more intense than they would be without human-caused climate change. Global warming also makes extreme rainfall events like the one that triggered mid-July floods in Germany, Belgium, the Netherlands, and Luxembourg between 1.2 and nine times more likely to occur in the region.
At least 220 people died in Germany and Belgium because of swollen rivers and floods that raged through entire towns, knocking homes off their foundations. The disaster was triggered by heavy rainfall that smashed records as the amount of water that might normally fall over a span of a couple of months instead came down in just two days.
“This event demonstrates once again in 2021 that extremes breaking observed records by far, exacerbated by climate change, can strike anywhere, induce huge damages and cause fatalities. Western Europe’s local and national authorities need to be aware of the increasing risks from extreme precipitation to be better prepared for potential future events,” Frank Kreienkamp, head of the Regional Climate Office Potsdam at the German weather service Deutscher Wetterdienst, said in a statement today from the World Meteorological Organization.
Human activity is the main culprit behind the more extreme weather we’re beginning to experience, a landmark United Nations climate report found earlier this month. By burning fossil fuels, humans have unleashed greenhouse gases that heat the planet, intensifying the water cycle.
That UN report aggregated the findings from hundreds of “attribution studies” that determine if climate change supercharged individual weather events. The new study on Europe’s July floods is one such attribution study, released yesterday by an international group of 39 researchers. Though their study hasn’t yet been published in a peer-reviewed journal, the researchers used established methods to quickly analyze the event.
They looked back at rainfall records and modeled how much rainfall the area might have received with and without the influence of climate change. They started by homing in on two regions that were hit hard by the floods: Germany’s Ahr and Erft region and Belgium’s Meuse region. But with this particular study, the researchers came up against more challenges than they have with other attribution studies. They lacked data on river flow over time, in part because floodwaters washed away measurement stations. They also had limited long-term, local data, so they broadened their study to a larger area of Western Europe. Because of those limitations, the report gives a wide range for how much more likely climate change made the floods.
Extreme weather attribution is a field of study that’s growing in leaps and bounds. Thanks to more computation power, more advanced models, and remote sensing, scientists can now tie the climate crisis to individual weather events with more speed and certainty than they were able to just a few years ago.
“This is a really exciting, cutting-edge field right now,” Alex Ruane, one of the authors of the recent UN report and a research physical scientist at the NASA Goddard Institute for Space Studies, told The Verge this month. “Methodological advances and several groups that have really taken this on as a major focus of their efforts have, in many ways, increased our ability and the speed at which we can make these types of connections. So that’s a big advantage.”
Scientists will need that advantage as they study more extreme events. For now, global warming has reached about 1.2 degrees Celsius above pre-industrial levels. When it reaches 2 degrees Celsius, rainfall from a similar event in Europe could be up to 6 percent more intense, according to the attribution study. That falls in line with findings from the UN report, which also predicted more severe rainfall and floods for Western and central Europe as the planet heats up.