In brief
A net decline of more than 900,000 city trees was recorded across 195 German municipalities between 2018 and 2025.
Offenburg, Lahr, and Mannheim ranked at the bottom of the DUH heat check, with Offenburg's canopy cover at only 13 percent.
Only Kiel and Wuppertal received green ratings in two of three categories; Berlin and Potsdam also met the 30 percent canopy cover benchmark.
All 195 cities received a red card for increased surface sealing since 2018, including the top-ranked municipalities.
The organisation called on federal building minister Verena Hubertz to mandate de-sealing and urban greenery in all construction and renovation projects.
A shrinking urban canopy
Germany's cities have lost nearly one million trees in the past seven years, according to the 2026 "Hitze-Check" (Heat Check) published by the environmental and consumer protection group Deutsche Umwelthilfe (DUH). The study examined 195 municipalities with more than 50,000 residents, combining satellite imagery with data on summer temperatures, population density, and the expansion of sealed surfaces such as roads and car parks. The findings paint a picture of urban areas increasingly ill-equipped to handle rising temperatures.
“If this trend continues, we will be living in hostile concrete deserts in just a few years.”
The net loss of more than 900,000 trees is not a problem that can be reversed quickly, DUH federal managing director Barbara Metz warned at the report's presentation in Berlin. She stressed that urban greenery is not merely decorative but a central prerequisite for health and quality of life.
The best and worst performers
Only two cities, Kiel and Wuppertal, received a green light in two of the three main evaluation categories. At the opposite end of the ranking, three municipalities in Baden-Württemberg — Offenburg, Lahr, and Mannheim — were classified as heat hotspots. Mannheim had already occupied last place in the previous year's check. Offenburg performed particularly poorly on the new metric of canopy cover, with trees shading only about 13 percent of its urban area.
- Offenburg
- 13 %
- Brandenburg an der Havel
- 26 %
- Cottbus
- 27 %
- Frankfurt (Oder)
- 27 %
- Kiel
- 32 %
- Berlin
- 32 %
- Potsdam
- 34 %
Data from the article text
In North Rhine-Westphalia, eight cities fell into the worst category, while roughly 70 landed in the middle tier. Wuppertal was the sole NRW city to achieve the top overall rating. In Rhineland-Palatinate, Ludwigshafen and Worms ranked fourth and sixth nationally among cities with the worst heat protection.
Berlin and Potsdam: shade-rich but losing ground
Berlin and Potsdam are among the few large cities that meet the scientifically recommended benchmark of at least 30 percent canopy cover. Berlin reaches just over 32 percent, while Potsdam sits at around 34 percent. Yet the capital still lost approximately 57,000 trees between 2018 and 2025, one of the highest absolute losses among the cities studied. Potsdam shed nearly 8,700 trees in the same period.
“Green heat protection from trees is dwindling; cities without sufficient tree shade will become unhealthy to unbearable cities.”
Heinrich Strößenreuther, founder of the BaumEntscheid initiative, pointed to Berlin's citizen-led climate adaptation law as proof that residents can force change. The law, passed unanimously across party lines, mandates one million street trees and 4,000 mini-parks.
Sealed surfaces and systemic failures
The DUH issued a red card to all 195 cities on the metric of surface sealing. Even top-ranked Kiel and Wuppertal have more paved-over land today than they did in 2018. The organisation is calling on federal building minister Verena Hubertz (SPD) to introduce binding requirements for de-sealing and more urban greenery in every renovation, road reconstruction, and construction project.
“We demand binding requirements from the building minister for de-sealing, more urban greenery, and thus more shade — for every renovation, every road reconstruction, and every construction project.”
The DUH recommends municipalities adopt the 3-30-300 rule: at least three trees visible from every home, 30 percent canopy cover in the neighbourhood, and a green space no more than 300 metres away.
A warming country
Germany has warmed by 2.5 degrees Celsius compared to pre-industrial levels, according to the German Weather Service (DWD), making it disproportionately affected by global heating. Heatwaves are becoming more intense and more probable, carrying particular health risks for the elderly and those with pre-existing conditions. The health ministry warns that multi-day heat periods above 30 degrees place significant strain on the body. City trees can lower pavement temperatures by up to twelve degrees, the DUH notes, making their loss a direct public health concern.