Kassel's heat alarm: Climate change is increasing urban heat islands!

Kassel's heat alarm: Climate change is increasing urban heat islands!

On August 29, 2025, a pioneering project to investigate urban climate conditions in the city will start at the University of Kassel. The Kassel Urban Climate Observation Network (KUCON) is being implemented in the city to better understand the interactions between development, vegetation, relief and climatic conditions. Prof. Dr. Britta Jänicke leads this project and emphasizes the growing relevance of the urban heat island effect in Kassel, which is a direct consequence of global climate change. Particularly affected are districts such as Vordere Westen and the city center, which are characterized by their dense development and lack of green spaces.

In recent years, the number of tropical nights, i.e. nights with temperatures above 20 degrees Celsius, has increased significantly. This development is alarming and requires precise data to develop targeted adaptation strategies for climate-resilient urban planning. The measuring stations, which are installed using existing urban infrastructure such as street lights, measure basic meteorological parameters such as air temperature, humidity and precipitation. This data will initially be made available to a research team with the prospect of later public accessibility.

Urban heat island and its effects

Again Weather Service reported, urban conditions such as underground development or dense development often result in cities being warmer than rural areas. These urban heat islands are not only uncomfortable for residents, but they also have a significant impact on the local climate. Evaporation is reduced in urban areas, lowering humidity and reducing the likelihood of fog formation.

Temperature differences between the city and the surrounding area can be up to 5 degrees Celsius. This means that cooling down living spaces becomes problematic during the summer nights. The storage effect of urban terrain means that heat stored during the day is only released into the environment late in the evening, which further increases nighttime temperatures.

Countermeasures and challenges

To counteract the dangers of urban heat islands, various measures are proposed. These include reducing absorbed solar energy through light-colored paint, increasing evaporation through targeted greening and creating urban water areas. However, these approaches also pose risks, such as the possible increase in mosquitoes due to new bodies of water. In addition, an increased proportion of trees can have both positive and negative effects on air quality and ozone formation.

The KUCON project is initially scheduled to run for five years, with the possibility of an extension. Together with the student employees Till Wiesehoff and Max Gaußmann as well as doctoral student Shakir Ahmed, Prof. Dr. Britta Jänicke is working on the foundations of better urban planning in order to overcome the challenges of climate change and improve the quality of life of Kassel's population. The knowledge gained could make a significant contribution to the creation of climate-friendly cities and thus represent an important step in adapting to the consequences of climate change.