Extreme rain is an increasing problem in urban areas resulting from climate change. In Wuhan, I experienced a rainfall of 200 millimeters for about four hours bringing traffic in the city to a complete stand still. I was also in Beijing, when we had a rainfall of 450 millimeters over eight hours. And this was totally extreme. Streets were empty, I had to walk home from the office in the middle of the rain. And I was lucky because I fell only into one sewer, a small, shallow sewer. Not so deep, so I could get out again, but I was totally soaked when I got home. Also, in Copenhagen, we have experienced heavy rainfall in 2009. There was a big storm which dropped 150 millimeters rain over the city in the span of two hours. And resulting from this, Copenhagen's started its climate change adaptation plan. Fundamentally, what happens is that the increase of atmospheric temperature, the increase of sea temperature, increases the evaporation from the sea, and in turn, it increases the intensity and frequency of heavy rainfall. In Denmark, the 2009 flooding of Copenhagen led to all municipalities being asked to prepare climate change adaptation plans. The first step is a risk assessment, meaning that risk is equal to frequency, times the losses. In the case of Copenhagen, hydrology, topography, and the financial value of assets, buildings like we have around us here. This risk assessment reveals that it would be impossible to protect Copenhagen by building of sewers, traditional sewers. It would not be impossible, but it would be financially prohibitive to have to construct sewers to separate the rainwater from the waste water throughout a densely built city. So instead, Copenhagen started on a series of what we called low impact development measures. Today we have moved out to in the district of Copenhagen to see a demonstration project for adaptation of the city to climate change. It consists of three segments. There is a hill at one end, a grassy hill where people, they can bathe in the sun. And it also covers a sedimentation basin, where water from the adjacent buildings, and from the street, is channeled into a basin, where sediment and impurities are kept, and can be cleaned out at intervals. From this sedimentation of this hill, the square slopes down to some retention basin at the [INAUDIBLE]. And in the middle we stand here at Mole Recreational Area, where the local inhabitants they can attend, sit and enjoy a cup of coffee in the sun. There's also these living sculptures here, these rain drops that the children can play at and the adults as well if they want. At the far end, we have the real climate change adaptation of this square. This is two of three basins we shall link together, and they have triple function. First of all, its a retention basin, which keeps the water, which can store the water from extreme rainfall for a while, and thereby reduce the runoff to the streets or to the sewers. Second, it contains a root zone, it's a root zone system which treats the water for any impurities that are left, especially nutrients. And certainly it is, this basins they are open in the bottom so water can seep from the basins into the ground water and reach out to the ground water. Finally, bare vegetation is important because it adds moisture to the local climate so this certain area and thereby it has a good impact on microclimate. All together this is an example of how in a recreational area can be combined to the practical purpose of adapting the city infrastructure to climate change. We call it low-impact development because it does not require building a lot of infrastructure. It is limited to this small square and a number of measures that can increase or improve the living conditions of the local people while at the same time serving nature and climate change adaptation.
