Environmental Action Germany has published a heat check for Germany. The study shows the extent to which people are exposed to extreme heat in their residential area. 190 cities in Germany were examined and a new Heat Exposure Index (HBI) was developed. This involves dividing the inhabited areas of a city into grids and evaluating them according to four criteria: sealing, green areas, surface temperature and population density. If the HBI value is higher or lower than the national average, the area is considered to be severely or slightly affected by heat.
Karlsruhe is one of the cities with above-average heat stress
In a nationwide comparison, Karlsruhe’s heat stress index of 16.70 is well above the threshold value of 16.16, above which, according to the environmental organization Umwelthilfe, the city is “affected to an above-average degree”. This makes Karlsruhe one of the most heat-stressed regions in Germany and puts it roughly on a par with Magdeburg (16.68) and Nuremberg (16.71).
The average surface temperature in the summer months is particularly striking at 36.68 °C, which is very high. Karlsruhe also has a comparatively high degree of sealing of 48.06% – a sign of a high level of development with little open ground. Although the green volume of 3.35 m³ per square meter is in the average range, this is not enough to compensate for the negative effects of heavy sealing and high temperatures.
The high proportion of sealed surfaces and the dense development ensure that the city heats up considerably in summer and only releases the stored heat slowly, even at night. This puts a particular strain on older people, small children and people with pre-existing conditions.
There is a need for action in Karlsruhe
The figures show: Karlsruhe faces major challenges when it comes to heat protection. To ensure the quality of life in the future, more unsealed surfaces, targeted urban greening and heat protection measures in public spaces are needed. Municipal adaptation strategies and funding programs should be targeted at those areas where the impact is greatest.
Some projects have already been launched in Karlsruhe. For example, the development plan “Greening and climate adaptation in the city center” aims to secure the city’s green spaces and provide more shade and better evaporation of rainwater through seepage into the groundwater, especially during extreme heat waves. In addition, these unsealed green spaces offer protection against heavy rainfall, as flooding can quickly occur if there are too many sealed surfaces.
City Councillor Friedemann Kalmbach (FÜR Karlsruhe) is nevertheless concerned about Karlsruhe’s performance in the heat check: “We urgently need to take action in this area. The fact that we are so far behind in the heat check is also an indicator of the quality of life in our city. If you can only find a few shady places in the city center in summer and the flooring reaches 40 °C, then that is not attractive. In the past, FÜR Karlsruhe has presented several concepts to green the city center: We advocate trees on the market square as well as more unsealed squares and the concept of ‘Karlsruhe as a climate-friendly sponge city’, where rainwater is collected through green roofs, rainwater basins and permeable surfaces such as parks or other unsealed areas and evaporates in hot phases, thus cooling the city. So we have many opportunities to counteract this problem!”
