A man on his paddleboard on a flooded city street, subway staircases that look like waterfalls and a bus plowing through deep water as if it were a motorboat. Such images of Berlin mirror those witnessed in many other cities confronted with extreme weather throughout Germany over the last several weeks.
So far the summer has been, at least in terms of weather, one thing above all: extreme. As a result, the German Meteorological Service (DWD) declared July 2017 the rainiest month Germany has seen since measurements thereof began back in 1881. For climate researchers, such extremes are evidence that climate change is affecting everyday life. That means that summer will now be a roller-coaster of hot, humid days and heavy rainfall. This is a tweet from the Berlin public transport service's advertising campaign, titled "Because we love you." It says, "We like to do a few laps in the morning," referring to the city's recent flooding.
New weather patterns, new challenges
New weather patterns mean that cities, above all, are facing major problems. They are being forced to deal with massive amounts of water brought on by those heavy rains. And incessant rain means the volume of water falling in cities cannot be absorbed and that sewer systems overflow. The result: Streets flood, basements fill up with water and firefighters are in action around the clock.
Rising mercury can also be a major problem. Densely populated cities and urban areas are especially hampered by the extreme heat. Temperatures in cities are often much higher than in surrounding rural areas – in summer temperatures can be up to ten degrees higher (18 degrees Fahrenheit). Air supply is the main reason for that difference. Also, an exponential increase in the amount of buildings and streets means that there is simply much more surface area to absorb and store more heat.
"It took a while before city planners realized that this was an issue that they would have to come to grips with," says Christian Hartwig from the city of Cologne's environmental agency.
Climate change is here
The theory of climate change is certainly present in people's minds: Numerous German cities, such as Cologne, have begun to develop climate adaptation concepts over the last several years. They have tasked experts with developing improved measures for dealing with storms and heavy rain in the future.
There is no shortage of resources: "Urban climatologists have come up with a number of well-established concepts that have proven useful and effective over the last several decades," explains Dirk Dütemeyer. A climatologist from Essen, he has compiled a number of assessment reports on how well urban planning is positioned to deal with the effects of climate change.
He says architectural steps must be taken to address rising temperatures: Buildings must be designed so that they store less heat. Light-colored facades help to that end, as do green roofs and facades, which help cool buildings but also help control rainwater: "If you could green square kilometers of roofs, then you would have the added advantage that you could absorb water during heavy rainfalls and then disperse it later," explains Dütemeyer. That would keep streets from flooding so quickly.
But that is easier said than done: "You can't just order homeowners to undertake such measures," says Beate Profe, who heads the city planning section of the Berlin Senate's Department of Urban Development and Housing. For some time now, Berlin has been offering homeowners advice and information about the advantages of green roofs.
Other cities are trying to win over homeowners by offering subsidies: Last year, Hamburg began a roof greening program. Smaller cities and municipalities are also making money available to homeowners for such projects.
Rip up the asphalt
Asphalt surfaces are also a major problem when it comes to summer heat. In response to the problem, the city of Bonn, for instance, has begun a project that it calls "Nature in the gray zones." In it, businesses "unseal" surfaces – that is they remove asphalt from their entryways and parking lots in order to make the city greener. Other cities around Germany have also picked up on the idea.
There is no shortage of clever ideas on how to combat the problem of climate change – the bigger issue is the implementation of such ideas. Cities already exist, therefore it makes it difficult to change much – one example is of course drainage infrastructure.
City sewer systems were installed at a time when planners were not confronted with such regularly occurring heavy rainfalls. That is why those systems have been so prone to flooding throughout Germany over the last several weeks. Would replacing them solve the problem? "That's a bold idea," says climatologist Dütemeyer. "But who is going to pay for it?" Nevertheless, major cities like Berlin are building much more underground storage space for rainwater.
City planners are focused on the future. "New construction is an area where we can say, 'from now on we will build with an eye towards the next 100 years.' And we need to apply everything that we know today," says Beate Profe. She cites as an example one area of Berlin in which "no-drain" settlement areas are being developed. In real terms, that means that rainwater is collected in grass troughs and then slowly seeps into the ground.
It is utopian to envision completely rebuilding existing cities – that is something that climatologist Dütemeyer acknowledges. He realizes that his suggestions can never be completely implemented – whether for organizational, financial or political reasons. "The climate change component is just one of many that must be considered when planning," he says. But Dütemeyer still believes enough is being done: "The most important thing is that city planners are sensitive enough to realize that the problem exists and that they acknowledge it."