Frequent wet days can crank down economic growth, say researchers 

Economic growth goes down when the number of wet days and days with extreme rainfall go up, a team of scientists at the Potsdam Institute for Climate Impact Research I(PIK) in Germany has found.

The analysis statistically evaluated data of subnational economic output for 1,554 regions worldwide in the period 1979-2019, collected and made publicly available by the Potsdam Institute and the Mercator Research Institute on Global Commons and Climate Change (MCC), who led the study.

Rich countries badly hit 

Rich countries are most severely affected and therefore the manufacturing and service sectors, according to their study published as cover story in Nature. 

The scientists combine subnational economic output data with high-resolution rainfall data. A combination of ever increasing detail in climatic and economic data is of particular importance in the context of rain, a highly local phenomenon, and revealed the new insights.

By loading the atmosphere with greenhouse gases from fossil power plants and cars, humanity is heating the planet, the study says. Warming air holds more water vapour that eventually becomes rain. 

Warming air, more vapour

Data analysis of more than 1,500 regions over 40 years shows a clear connection and suggests that intensified daily rainfall driven by climate change will harm the global economy.

“This is about prosperity, and ultimately about people’s jobs. Economies across the world are slowed down by more wet days and extreme daily rainfall, an important insight that adds to our growing understanding of the true costs of climate change,” says Leonie Wenz at both the PIK and the MCC. 

“Macro-economic assessments of climate impacts have so far focused mostly on temperature and considered, if at all, changes in rainfall only across longer time scales such as years or months, thus missing the complete picture,” explains Wenz. 

Rainfall distribution pattern

“While more annual rainfall is generally good for economies, especially agriculture-dependent ones, the question is also how the rain is distributed across the days of the year. Intensified daily rainfall turns out to be bad, especially for wealthy, industrialised countries like the US, Japan, or Germany.”

“We identify a number of distinct effects on economic production, yet the most important one really is from extreme daily rainfall”, says Maximilian Kotz, first author of the study and also at the PIK. 

“This is because rainfall extremes are where we can already see the influence of climate change most clearly, and because they are intensifying almost everywhere across the world.”

Daily rainfall trends

Although atmospheric dynamics make regional changes in annual averages more complicated, daily rainfall extremes are increasing globally due to this water vapour effect.

“Our study reveals that it’s precisely the fingerprint of global warming in daily rainfall which have hefty economic effects that have not yet been accounted for but are highly relevant”, says co-author Anders Levermann, Head of the PIK’s Complexity Science domain, professor at Potsdam University and researcher at Columbia University’s Lamont Doherty Earth Observatory, New York. 

Shock from weather extremes

“Taking a closer look at short-time scales instead of annual averages helps to understand what is going on: it’s the daily rainfall which poses the threat. It’s rather the climate shocks from weather extremes that threaten our way of life than the gradual changes,” Levermann pointed out.

“By destabilising our climate we harm our economies. We have to make sure that our burning of fossil fuels does not destabilise our societies, too,” he cautioned. 

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