Berlin - Collapsed homes, submerged streets, dozens dead and hundreds missing - the consequences of the heavy rain in Germany, Belgium, Austria and the Netherlands are terrifying. And the current flood disaster could be a foretaste of the extreme weather scenarios scientists expect as the climate heats up. 

Although the current disaster cannot be definitively chalked up to climate change, many scientists agree that such extreme weather events will increase in number thanks to global warming.

"More than 30 years ago, climate models already predicted that extreme precipitation would become more frequent, while days with weak rain would become rarer," explains Stefan Rahmstorf of the Potsdam Institute for Climate Impact Research (PIK). For every additional degree of warming, the air can absorb seven per cent more water vapour, resulting in more rain, says Rahmstorf. At the same time, the number of days with normal levels of precipitation are expected to decrease due to concentrated heavy rainfall.

More extreme weather in Berlin and Brandenburg

Berlin and the surrounding state of Brandenburg are also expected to face more extreme weather events such as heavy rain and heat waves, according to the German government's current climate impact and risk report. The risk of heavy rain and flooding will be greatest in cities, including Berlin. This is because many areas are built up. Rainwater can't run off and torrents can develop, as was recently seen in the flood disaster in western Germany.

In Berlin, underground tunnels and shafts would also be at risk. Sewage systems could be overloaded, according to a report titled "Adaptation to the Consequences of Climate Change" (AFOK) commissioned by the Berlin Senat. According to the study, more extreme weather would disrupt the city's supply chains. Railway lines and roads could be blocked for traffic and deliveries of supplies.

Climate researchers at PIK predicted in a 2018 study that stronger flood protection would be necessary by the 2040s. Without appropriate countermeasures, eight times more people in Brandenburg will be affected by floods between 2035 and 2044 than today, according to the scientists. 

More droughts, more rain

Even if the number of days with heavy rainfall increase, large swathes of eastern Germany and parts of central Germany are expected to remain the driest region of the country, according the federal government's risk assessment. Berlin and the surrounding area will become one of the hottest regions in Germany.

Researchers at the Climate Service Center Germany (GERICS) have made their own predictions for Berlin and Brandenburg. According to their calculations, if greenhouse gas emissions are not reduced, Berlin could experience a temperature increase of up to 5.3 degrees Celsius by the end of the 21st century, compared to the reference period from 1971-2000. According to the AFOK study, in 2100 Berlin will have the climate of Toulouse today.

More heat deaths

Higher temperatures will have consequences for Berliners' health. In addition to minor complications such as sleep disturbances or lower productivity, heat waves can result in a higher number of cardiovascular emergencies, including heat stroke, dehydration and respiratory diseases, the AFOK study states. Older Berliners in particular will be at risk from the heat because their cardiovascular systems could be weakened. Researchers already identified around 20,000 heat-related deaths among over-65s in Germany in 2018.

New type of infection could appear in Berlin due to the rising heat, such as tropical diseases like dengue fever, which is transmitted by the Asian tiger mosquito, which could become native to Germany in the future. Another health consequence of climate change: the extension of the flowering period of plants and thus higher burdens for people suffering from pollen allergies.

Dark tarmac surfaces soften in the heat, meaning dangerous bulges could form in Berlin's road surfaces. Berlin's streets are already suffering from heat stress, says the AFOK study. In new construction projects attention must be paid to heat-resistant materials that can at the same time handle precipitation well and reflect solar radiation better.

Berlin's streets could be redesigned to drain water better. This is possible, for example, with the idea of the
"sponge city": rainwater should not simply flow away, but be collected - in reservoirs, on unsealed surfaces, in rainwater troughs, in parks, in newly created ponds and on green roofs. Then, during hot spells, the water evaporates and cools the neighbourhood - without any additional energy input.

Germany's Federal Office of Civil Protection and Disaster Assistance warns in a risk analysis paper that long periods of drought could lead to problems in supplying the population with drinking water. The drought monitor of the Helmholtz Centre for Environmental Research shows that the soil in Berlin and Brandenburg is already suffering from extreme drought. What's more, the water levels of Brandenburg lakes have never been as low as they are today. At Lake Peetsch in the north of Berlin, for example, the water level dropped by more than 90cm between 1958 and 2020. Lake Fresdorf, south-east of Potsdam, dried up completely in 2020.

Climate change will clobber Berlin's economy

Climate chaos will impact the local econony, predicts the AFOK study. First, extreme weather events can endanger buildings and facilities. Second, various economic processes could be impaired, ranging from logistics to water and energy supply to waste disposal. Third, climate change could affect the productivity of workers.

Heat waves could cause annual damages worth millions or even billions of euros, according to the scientists behind the AFOK study. These risks need to recognised and assessed on a company-by-company basis, the authors suggest.

Droughts, heat waves and heavy rainfall would have drastic consequences for agriculture. Animals and plants are already under heat stress due to the increased temperatures. The future could see more ruined harvests, new pests and flooded fields.

Another consequence of climate change that should not be underestimated: millions will probably flee from droughts or floods in the coming decades. The UN fears that by 2050, more than 200 million people worldwide will be displaced from their homes as a result of climate change. Other studies predict even higher numbers. The Sahel zone in Africa, Bangladesh and many South Pacific islands could be particularly affected. The refugees would probably head towards temperate zones, like Germany.

The effects of climate change are measurable today

Climate change is about much more than just a few degrees hotter weather. There is little doubt that the everyday lives of Berliners will be impacted and that the economy will suffer. Experts say the effects of climate change are already measurable today. According to data from the German Weather Service (DWD), the average temperature has already risen by 1.6 degrees Celsius compared to 1881. The number of days above 30 degrees Celsius have increased by 196 per cent since 1951 and days below zero have fallen by a good 50 per cent since 1951.

Adaptation measures are urgently required to mitigate the already unavoidable consequences of climate change, scientists emphasise in the various studies. Measures range from more trees to cool down cities, less paved over areas, better disaster protection, improved road drainage, air conditioning at workplaces and in public transport, investment in the health system and the improvement of early warning systems.

The reports stress, however, that the primary goal should be more ambitious climate protection policies. The DWD models show it's not to late to prevent a worst-case scenario.

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