Sizzling Summer Heat Index: How Your City Stacks Up
- 2 Min
City Heat Stress Intensity: Explore This Map to Determine Your Local Conditions - What's the current temperature in your city?
Unbearable heat stress is plaguing numerous German cities, with close to thirteen million residents exposed to extreme temperatures, as revealed by a study conducted by the German Environmental Association (DUH). This association utilized a "Heat Affected Index" to measure urban locales comprising intense heat, abundant concrete, and scarce greenery in cities with over fifty thousand inhabitants.
Leading the chart, negatively, are Mannheim, Ludwigshafen, and Worms, with 88-91% of their populations residing in hotspots of heat stress. The number of inhabitants exposed to extreme heat in southern German cities is substantially higher compared to their northern counterparts. Cities like Flensburg, Wilhelmshaven, and Kiel profit from milder summer temperatures, while Hattingen, Gummersbach, and Witten shine due to their abundant green spaces and relative scarcity of sealed surfaces.
Night and Day: Where it's Sweltering
Remarkably, Environmental Aid has designated 31 cities in the red category as especially vulnerable to extreme heat, including Frankfurt am Main and Magdeburg. Cologne, Berlin, and Munich find themselves in the middle yellow category. To the relief of residents in Hamburg, 28 cities have received a green label, meaning they are among the least affected.
To create this index, DUH teamed up with Luftbild Environmental Planning GmbH, a company based in Potsdam, Germany. They divided the country into 100x100-meter grids and determined the summer surface temperatures, degree of sealing, green volume, and population density for each square. Scores were awarded based on deviations from average values, and census and satellite data were used.
DUH has refined its already published heat check from last year, now incorporating additional information on average summer surface temperatures and population density.
The Power of Concrete and Green
Heat stress occurs when sunlight absorbs and is trapped by sealed surfaces like roads, parking lots, and rooftops, preventing water from seeping in and evaporating, which would promote cooling. As a result, these surfaces heat up and release stored heat for an extended period, amplifying heat stress, particularly in urban environments. Conversely, green spaces such as meadows, hedges, or trees have the opposite impact due to moisture evaporation, providing cooling effects, especially during extreme heat.
Trees, a remarkable aid in countering heat stress, can lower temperatures by up to 10°C in the surrounding area, according to the Ministry of Construction's heat protection strategy of last year. Open water surfaces and cool air corridors further contribute to cooling. Drinking water fountains provide much-needed refreshment.
City officials can take several measures to minimize heat stress, including implementing the "Sponge City" concept, which allows for better water absorption and storage to help manage extreme rain and dry spells. Green roofs, facades, parks, and trees stimulate evaporation, while cool air corridors bring in cooler air from surrounding areas.
Find out how your city measures up in the table below:
- Heat
- Weather
- German Environmental Association e.V.
[1] Climate Change, Heatwaves, and Extreme Heat: A Review of the Literature. (n.d.). Retrieved March 03, 2023, from https://www.who.int/publications/i/item/climate-change-heatwaves-and-extreme-heat--a-review-of-the-literature[2] Berlin Energy and Climate Protection Programme 2030 (BEK 2030). (n.d.). Retrieved March 03, 2023, from https://www.klimaschutz.berlin/filestore/74215/0/PROGRAMM_FAHRENPLAN_BERLIN_2030_FR_E3e8d74a237ef0a0fc0c99f1931abd75.pdf[3] Heat Affected Index – German Environmental Aid (DUH). (n.d.). Retrieved March 03, 2023, from https://www.duh.de/reaktion-und-kampagne/aktuelle-kampagnen/hitze-hitze-hitze[4] Healthy Urban Design Index (HUDI) – WHO Europe. (n.d.). Retrieved March 03, 2023, from https://www.euro.who.int/en/healthy-cities/what-we-do/healthy-urban-design-index-hudi-hudi
- The German Environmental Association (DUH) has collaborated with Luftbild Environmental Planning GmbH to develop an employment policy for reducing heat stress in cities, which involves the study of science such as environmental science and climate change.
- The implementation of the "Sponge City" concept, suggested as a measure to minimize heat stress, is rooted in the principles of fitness-and-exercise, as it encourages better water absorption and storage, much like muscles absorb and release nutrients for energy.
- In an effort to improve the health-and-wellness of city residents, city officials are encouraged to implement cooling strategies like green spaces and cool air corridors, as demonstrated by the cooling effect trees have on temperature, reducing it by up to 10°C, akin to the beneficial effects of regular exercise on heart rate.
