Climate models predict that climate change will cause more droughts in Southern Europe and heavier rainfall in the north. A new study in Scientific Reports shows that these projections can already be observed today. Elke Bunge reports.
‘Herwart’ and ‘Xavier’ brought gale-force winds and heavy rain to Northern Germany last month. ‘Lucifer’, in contrast, was responsible for heatwaves and droughts in the Mediterranean region in August.
Such extreme weather events – heatwaves, floods and droughts – are causing more and more damages in Europe: the south is struggling with crop failures due to prolonged droughts, while the north is experiencing storm and flood damages.
Last year alone, storm with heavy rainfall caused nearly ten times more insurance losses than the previous year, according to the German Insurance Association (GDV).
And the figures don’t look much better this year. Take for instance crop failures due to drought: Italy has received only one-tenth the usual rainfall in 2017. The farmer’s oganization Coldiretti estimates the damages due to crop failures caused by persistent drought at 2 billion euros.
Dry south, wet north
All of this corresponds with the projections that climate scientists have been making for years. Overall, temperatures are rising across Europe, especially in the south where it is getting drier and drier, and in Central and Northern Europe with its heavier rainfall.
But are these current trends the consequence of climate change? And if yes, is there a clear geographical boundary between drought and precipitation? Where would this be?
These are some of the questions asked by an international team of researchers led by James Stagge at Utah State University. They analysed meteorological data from the 1950s to the present and compared them with various climate models.
Projections are correct
The results show that droughts have indeed become more frequent in Southern Europe. Reality thus corresponds to the various climate simulations. According to the researchers, temperatures – which have been steadily rising in Europe since the 1970s – are to blame.
With a temperature rise of 1 degree Celsius, 7 per cent more water can be absorbed by the air. This means that when the Mediterranean region is affected by a low pressure system, the atmosphere sucks the humidity like a sponge full of water, before moving eastwards past the Alps to rain down in Central and Eastern Europe. As a reult, these areas are more and more influenced by the changing weather conditions in the Mediterranean region.
“When you include evapotranspiration, the border from where it’s getting wetter to where it’s getting drier is pushing farther and farther north,” said Stagge. “So it’s not just the Mediterranean that’s getting drier. It’s pushing up into Germany and England. It’s moving everything farther north.”
How extreme will it get?
With their study, the researchers have confirmed two important pieces of information: the droughts that we have experienced in the past and those we are currently experiencing in Europe have “all the hallmarks of climate change”.
“There have been a lot of projections, but now that we’re starting to see the projections and observations line up, it’s not a question of ‘is it happening?’ It’s a question of ‘how much?’ And ‘what do we do?’” said Stagge.
The new findings are important to the scientific community, but they could also influence public policy and Europe’s agriculture industries as they cast doubt on the indices used by many drought monitoring agencies to determine what constitutes a drought and whether or not farmers are entitled to compensation.
“The research highlights the increasing need to carefully define drought in a changing climate,” explained Stagge. “Indices that were standardized in the past may drift significantly in a changing climate depending on how a data set is measured and what time period is considered.”