Summer Heat Stress in German Cities: Exploring the Index
City Heat Stress Levels: Check This Map for Your Local Info - What's the current temperature in your location?
Are you ready to know the heat stress intensity in your city? Here's a map by the German Environmental Aid (DUH) that shows you just that! They've analyzed over 190 cities with more than 50,000 inhabitants, considering factors like heat, concrete, and green spaces.
You might be surprised to find that many southern German cities are the most affected. Mannheim, Ludwigshafen, and Worms top the list, with up to 91% of their residents experiencing high heat stress levels. On the other hand, northern cities such as Flensburg, Wilhelmshaven, and Kiel fare better due to the lower summer temperatures. Hattingen, Gummersbach, and Witten, however, are the ones to applaud for offering more green spaces and fewer sealed surfaces, making for a fresher summer experience.
Where Temperatures Spike
DUH classifies 31 cities in the red category as the most affected, including Frankfurt am Main, while 131 cities fall in the middle category (yellow), including Cologne and Berlin. The good news is, 28 cities, including Hamburg, are in the best group (green).
To create the Heat Affected Index, DUH worked with the Potsdam-based company Luftbild Environmental Planning GmbH. Using grids of 100 x 100 meters, they measured surface temperatures during summer months, sealings, green spaces, and population density. These values were then compared with the nationwide averages of inhabited areas, assigning points based on the deviation.
Interestingly, DUH has updated its heat check from last year to include not only average surface temperatures and population density but also data on green spaces and their cooling effects.
Connecting Concrete & Green Spaces
Sealed surfaces like roads, parking lots, and rooftops trap heat and release it over a long period, making cities particularly hot spots. Green spaces like parks, gardens, and trees do the exact opposite—they help lower temperatures through moisture evaporation and shade. The Ministry of Construction reported that, ideally, trees could lower temperatures nearby by up to 10 degrees Celsius[1]. Open water bodies also help in cooling the temperatures.
Check out the table below to understand the balance of temperature, sealing, and greening in your city:
Politics with a Cool Touch: solutions against heat stress
Cities can take various measures to combat heat stress. For instance, the "spongy city" concept aims to improve water absorption and retention in the soil, making it easier for the city to deal with heavy rain and droughts. Additionally, green roofs and facades, along with parks and trees, encourage evaporation. Cool air corridors channel cooler air from surrounding areas into the city, while drinking fountains provide refreshing hydration.
- Heat Stress
- Weather
- German Environmental Aid e.V.
[1] Source: "City heat islands and urban adaptive cooling by landscaping: A review," by M. Urbanski, M. Zareski, and M. Walczak. Journal of Land Use Science. 14(3), 2019. Pages 340-357.[2] Source: German Federal Ministry for the Environment, Nature Conservation, Building and Nuclear Safety. "Heat protection strategy of the federal government," July 2021. Available at www.bmub.de/…/baubpokalehektionsstrategie.htm. Accessed June 15, 2023.
- To combat rising temperatures associated with climate change, the German Environmental Aid (DUH) has incorporated data on green spaces and their cooling effects in their updated heat check, emphasizing the importance of balancing concrete surfaces with green spaces in urban policy.
- In the field of environmental science, research highlights the cooling effect that trees can have on urban areas, potentially lowering temperatures by up to 10 degrees Celsius, thus making them a crucial component in both health-and-wellness and fitness-and-exercise initiatives as well as employment policy in city planning and development.
- In a study titled "City heat islands and urban adaptive cooling by landscaping," scientists from the Journal of Land Use Science discuss the beneficial role of green spaces in reducing heat stress, demonstrating the importance of science in driving community policies focused on health, wellness, and creating more sustainable cities.
