‘Heaviest Rain Ever’ That Triggered Deadly Floods in Central Europe Made Twice As Likely By Climate Change, Study Finds

In a 2C warmer planet, an event like Storm Boris in Central Europe would be a further 5% more intense and 50% more frequent, World Weather Attribution said on Wednesday.

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The exceptionally heavy downpours that triggered deadly floods in Central Europe earlier this month, affecting two million people, were made at least twice as likely by human-made climate change, a new attribution report has revealed.

Storm Boris unleashed unprecedented rains throughout the region, causing rivers and reservoirs to swell to alarming levels. All affected countries – Austria, Czech Republic, Hungary, Poland, Romania, Slovakia, and northern Italy – experienced flooding and power cuts. Tens of thousands were evacuated and at least 24 were killed.

The four-day downpours were made at least twice as likely and 7% heavier due to human-made climate change, World Weather Attribution (WWA), an academic collaboration studying extreme event attribution, said on Wednesday. The group’s rapid attribution study revealed that the amount of rain that fell between September 12-16 was the heaviest ever recorded across Central Europe, and covered an area even greater than previous historical floods recorded in 1997 and 2002.

The downpours formed as cold polar air from the north met with warm air in Southern Europe as it flew over the Alps. Heat and moisture drawn up from the Mediterranean and the Black Sea, which have been much hotter than usual for more than a year, exacerbated the storm, fuelling it for days before it moved back inland.

Days before the events unleashed, weather models flagged the potential of a “massive rainfall event” and “catastrophic flooding,” prompting scientists to raise the alarm and authorities to issue early warnings and prepare for the flooding. Ahead of the storm, Czech authorities released large volumes of water from tributary dams in the East of the country to bring reservoir levels down and create storage.

“These floods were big, widespread and hugely damaging. They were well forecast and the planning and action taken, by both individuals and authorities, undoubtedly helped save lives,” said Hannah Cloke, Professor of Hydrology at University of Reading and one of the authors of the study. “Yet many people still tragically died. For some, they were unable to imagine the effects of such intense rainfall. It is vital, as extreme rainfall gets more extreme, that we develop new ways of helping people understand the risks.”

WWA warned that the continuous burning of fossil fuels will further increase the likelihood and intensity of devastating storms. In a 2C-warmer world, an event like Storm Boris would be 5% more intense and 50% more frequent, the 24 researchers involved in the study warned.

The past nine years have been the hottest on record, with 2023 topping the ranking. Last year’s record-breaking temperatures can be partly attributed to the return of El Niño, a weather pattern associated with the unusual warming of surface waters in the eastern equatorial Pacific Ocean. However, despite the gradual weakening of the pattern, temperatures continued to rise. Earlier this month, European scientists confirmed that the world just endured its hottest summer on record. This string of record temperatures, they said, is increasing the likelihood of 2024 being even hotter than last year.

A warmer planet does not just impact events like Storm Boris. It also makes other weather events such as heatwaves and tropical cyclones more frequent and severe, besides contributing to further melting ice caps, rising sea levels, and the disruption of biodiversity and ecosystems.

The burning of coal, natural gas, and oil for electricity and heat is the single-largest source of global greenhouse gas (GHG) emissions. These are the primary drivers of global warming as they trap heat in the atmosphere and raising Earth’s surface temperature. Global fossil fuel consumption has more than doubled in the last 50 years, as countries around the world aim to improve their standards of living and economic output. In 2023, all three of the most potent GHGs – carbon dioxide (CO2), methane, and nitrous oxide – reached record highs.

The International Energy Agency (IEA) has urged countries to halt new gas and oil field projects, arguing that this is the only way to keep the 1.5C-compatible net-zero emissions scenario alive.

“The 1997 and 2002 floods in Central Europe were described as once in a century events, but two decades later, global warming has increased from 0.5 to 1.3°C, and they’ve happened again,” said Bogdan H. Chojnicki, a climatologist at Poznań University of Life Sciences and one of the study’s authors, adding that Europe is warming faster than the rest of the world. “The trend is clear – if humans keep filling the atmosphere with fossil fuel emissions, the situation will be more severe.”

Featured image: Wikimedia Commons.