On hot summer days, the air seems to glow over a paved road. The temperatures there can rise by ten to 20 degrees compared to green spaces. However, if there is a violent summer thunderstorm, the rain can at most drain through the sealed surfaces in the city into the sewer system. Rainwater is lost for nature in the city, also as a cooling element in damp meadows. Munich is the most sealed city in Germany. That should finally change.
According to the Department for Climate and Environmental Protection, 44 percent of the urban area is built up with roads or buildings. For comparison: According to studies, 13 percent of Potsdam is paved with paving, cities such as Freiburg, Heidelberg and Erfurt are less than 20 percent sealed.
Munich’s climate protection officer Christine Kugler is now calling on politicians to green the city more and to dismantle streets and buildings or to redesign them so that Munich does not heat up even more and valuable rainwater is lost. “Doing instead of measuring,” demanded Kugler on Tuesday at the meeting of the Environment Committee. Because so far the presentations have actually mainly described the degree of sealing in the city. And that is alarming: just through the construction of streets, paths and squares, sealing has increased enormously. The traffic areas grew by 20 percent between 1994 and 2015, which corresponds to an area of 717 hectares. For comparison: Munich has a total area of around 31,000 hectares.
Climate protection officer Kugler naturally sees the dilemma between the shortage of housing in Munich and the increasing density of the city, which is heating up more and more and offers less natural living space. The changes not only affect large new housing estates such as Freiham, where the degree of sealing of the area increased from ten to 25 percent between 1994 and 2019. In the Messestadt Riem, 47 percent of the area is now built with streets, underground garages or houses. Munich’s garden cities are also changing a lot. In an investigation of an area around Possenhofener Strasse east of the Garmisch Autobahn in the south of Munich between 2006 and 2019, some old houses were demolished there and “a much larger number of new larger buildings were built,” says the climate protection department’s decision paper. In many cases there are now underground garages that have almost the same floor space as the associated buildings.
Of course, this also has consequences for the environment: in underground car parks there are often no large trees, and the underground structures prevent the water from flowing naturally. In addition, large old trees are often felled in new buildings. The trees that were newly planted for this would take around 50 years to reach the same volume as the felled trees, says Kugler. But large trees are immensely important for the urban climate. They produce oxygen and bind large amounts of carbon dioxide, and they also cool the environment significantly.
So far, the city still lacks a real master plan as to how the further sealing of Munich can be stopped or even reversed. After all, the planning committee decided a few days ago to take the so-called sponge city principle into much greater consideration in the future. Roads are to be built with water-permeable surfaces where possible, and the entire city is to be given a networked green infrastructure with green spaces and trees. But so far several thousand trees are still disappearing from the urban area every year, mostly giving way to new buildings.