Climate change “Extreme summers are becoming more common”

Climate change “Extreme summers are becoming more common”

Climate change

Drought, danger of forest fires, circulatory problems: summer in Germany has been showing its dark side for weeks – and in the future we will have to be prepared for even more hot days and tropical nights. Climate experts are convinced of this. “There will still be good and bad summers, but the extreme summers will occur more frequently,” says Daniela Jacob, Director at the Climate Service Center in Hamburg. The institute is part of the Helmholtz Center Geesthacht in Schleswig-Holstein. According to Jacob, future climate scenarios show: Whether in urban development or in agriculture – everywhere there is a need to adapt to extreme weather. “We have to act today,” emphasizes the professor.

According to Jacob, there will be more periods of heat and drought as well as heavy rain and more violent storms in Germany by the middle of the century. “But by the end of the century it will become much clearer whether we have done climate protection or not,” she explains. The climate reacts very slowly. “Global climate protection measures introduced today will only take effect from the middle of the century.” Changes up to 2050 can only be influenced little.

For the period 2050 to 2100, however, there are still serious differences in warming possible, according to Jacob – depending on climate protection. This shows very clearly the number of hot days that cause temperatures to rise to more than 30 degrees: At the end of this century, according to the models, there are on average only three hot days more in Germany than in the comparison period 100 years before, if the goal of the Paris Climate Agreement – to limit global warming to less than two degrees – is really achieved.

But if greenhouse gases are released into the atmosphere as before, the so-called business as usual scenario, then there are twelve more hot days. The annual mean temperature would rise by around 3.7 degrees.

“That means extreme summers like 2003 or how likely this one can turn into a middle summer,” says Peter Hoffmann, meteorologist from the Potsdam Institute for Climate Impact Research. There will be a shift: “According to our calculations, the future Berlin will be the present one in 2050.” The temperatures in Freiburg, in turn, could then become Mediterranean. What might sound nice on the surface brings many problems with it. “The warmer it will be in the future in summer, the more we have to cool. In doing so, we use more energy, which will be really expensive, ”says the spokesman for the German Weather Service, Gerhard Lux, in Offenbach.

Harvest failures, fish deaths, low water levels in rivers and poor sleep are also some of the consequences of heat and drought – which can already be felt. “In addition, everyone only has 30 days of vacation, if not less,” says Hoffmann. “You have to do your daily work even in such extreme conditions, which of course also has an impact on productivity.”

According to Jacob, the climatic changes are also evident in winter: They become milder and more humid, the number of frost days decreases. “18 days less, if we pursue climate protection and if we continue as before, it will be over 55 days less,” explains Jacob. “But we need the frost for the vegetation.” The Climate Service Center advises politicians and companies on adaptation to climate change. It examines changes in the climate on the basis of regional simulations of the federally funded initiative called ReKliEs-De.

What specifically needs to be done today in order to adapt to these changes? “In Germany we can adapt to a certain extent, but it will hurt,” says Lux. According to Jacob, there is a conflict in the big cities: although densification saves energy, it is a problem for the important adaptation to the heat waves. “For that you would have to create ventilation corridors and bring a lot of green into the cities,” says the scientist.

The use of materials should be reconsidered. “I know that there are some regions in Europe that are thinking of building with clay again, because it simply stores moisture and coolness,” explains Jacob. When building houses, one should focus less on glass facades in the coming years. “Installing air-conditioning systems everywhere is not an alternative because they consume too much energy.” The entire sewer system in the cities must be adapted to more heavy rain. In agriculture, there is currently a discussion about varieties that are resistant to heat and drought stress.

According to experts, climate change can no longer be stopped, only contained with protective measures. “We can’t turn back the wheel,” says Lux. “But we can keep things from getting worse by the end of the century.”