As temperatures cool down, concerns over climate trends heat up: How Germany’s hot summer is a sign of future challenges

The hot summer may have had long-term effects on the climate in and around Germany. Omnified contributor Emily Bader examines the potential local and national impact of climate change in Berlin.

Photo by Jess Sweetman

A post for Omnified by Emily Bader

Benjamin Kraemer, an international postdoctoral fellow at the Leibniz Institute for Freshwater Ecology and Inland Fisheries in Berlin, usually jumps into Müggelsee to cool off after a game of beach volleyball. But a few weeks ago, he said, all swimming in the lake was banned: “There was a pretty intense cyanobacteria bloom.”

The cyanobacteria bloom was a result of the most recent heat wave, which according to Deutscher Wetterdienst (DWD), the German meteorological services’ climate monitoring tool, began in the last weeks of July, when average temperatures across Germany hovered around 30 degree Celsius during the day, or about 86 degrees Fahrenheit. This places last month as the fourth hottest July in over 100 years.

Cyanobacteria is a subset of phytoplankton, the microscopic organisms floating around in bodies of water, and appears as a green slick across the surface of bodies of water, often producing a fishy smell.

Though cyanobacteria is helpful in one way – it produces oxygen, just like any other plant – it also produces dangerous toxins which attack the liver, and the nervous and respiratory systems. Even if the cyanobacteria is washed up on shore and dries out, it can remain toxic for months.

The government issues warnings when the water is not safe for recreational use, such as when a cyanobacteria bloom occurs, like the one Kraemer described at Müggelsee.

Kraemer, whose research focuses on the effects of warming on lakes, said there’s evidence that if these warmer temperatures continue, they will have an effect on the amount of phytoplankton in the bodies of water already considered “green.” “Green” describes water that is nutrient-rich (as opposed to water that is “blue,” or nutrient-poor). This trend could signal trouble for Berlin residents and visitors who often take to one of the Berlin-Brandenburg area’s many lakes for some reprieve during the summer months.

The most recent heat wave is not only notable for the effect it is having on lakes, but also because it came during a drought. The intense dry period began back in May, according to the July and August 2018 reports from the European Drought Observatory. Jürgen Vogt, the scientific project leader at the Disaster Risk Management Unit of the European Commission’s Joint Research Centre, said that Berlin is particularly affected by this dry period, but that it could take anywhere from weeks to years to fully understand the severity of these environmental changes.

In the past weeks, fires the size of 500 football fields ripped through the forested areas southwest of Berlin, where buried World War II grenades and munitions set off by the flames are complicating the firefighting efforts. Vogt described low moisture levels in the soil that essentially clear the way for fires to spread quickly. Less water in general also means that water pollution is likely to increase, Vogt said.

Though heat waves and droughts have occurred in Germany before, Dr. Frank Kreienkamp, the head of the Potsdam regional climate office for DWD, said that this combination of both hot and dry weather is something that has not occurred in his recent memory.

He warned that if this trend of hotter summers combined with less rainfall continues, then it could have major impacts on Germany’s infrastructure and other sectors of the economy. Farmers have already faced major hits to this year’s crop production, with calls to both the Berlin regional government and the federal government for aid. Water-dependent transportation has been disrupted by decreased water levels, making it next to impossible for boats to navigate drained waterways.

Everything from concrete motorways cracking under the extreme heat, to power plants that depend on water to cool down their systems could be affected. Kreienkamp encouraged an active discussion for how to cope with the effects of extreme weather events such as this one. He said his research suggests a continued change in the next 50 to 100 years.

“We build for the climate conditions that we know, but not for the climate conditions that might come,” said Kreienkamp.

Kraemer said that climate change has the potential to make his job of monitoring bacteria in water and reducing the amount of toxins more difficult. But still, he said, water quality in the city of Berlin is getting better all the time: As new technologies and standards evolve, the ability of treatment systems to keep toxins out of our drinking water is rapidly improving.