display
Cities around the world could increasingly turn into dry heat islands by the end of the century as global warming progresses.
In the worst case, there is a risk of an average temperature rise of more than four degrees Celsius in urban regions by 2100 with a simultaneous decrease in humidity, as scientists write in the journal "Nature Climate Change".
The authors propose to counteract this effect with greener cities.
According to the “Atlas of the Human Planet” of the EU, a good three quarters of the world's population live in metropolitan areas - a number that is likely to continue to grow.
Cities tend to heat up significantly more than rural or suburban areas due to the large number of concrete and asphalt surfaces.
This effect makes cities warmer and drier and represents a health hazard for the residents. This can result in increased cardiovascular diseases.
A study in the journal "The Lancet" came to the conclusion that in Germany in 2018 around 20,200 deaths among people over 65 were related to heat.
Low water on the Rhine near Cologne in May 2020
Source: picture alliance / Goldmann
display
It is therefore important to be able to better estimate the consequences of climate change, especially for urban regions.
A team led by environmental and atmospheric researcher Lei Zhao from the University of Illinois therefore developed a statistical model in which 26 different climate models with medium and high emission scenarios can be applied to urban areas.
The researchers focused on the development between the period from 2006 to 2015 compared to the period from 2091 to 2100.
The result: In the worst case (RCP 8.5.) Urban regions could warm up by an average of 4.4 degrees Celsius in the months of June to August; in climate models with fewer emissions (RCP 4.5.) This warming would still amount to 1.9 degrees Celsius .
With the exception of coastal cities, the scientists also predict an almost nationwide decrease in relative humidity.
In their work, the authors cite a German study by the Climate Service Center Germany (GERICS), which presented and modeled the difference in temperature and humidity for Berlin and the surrounding area.
That modeling also showed that the urban agglomeration of Berlin becomes warmer and drier than the surrounding area as climate change progresses rapidly.
display
The authors of the current study hope that urban planners and political decision-makers will use the new statistical model to better estimate the respective effects of climate change for their specific urban regions and to take appropriate adaptation measures.
In the study, the authors mainly mention the keyword “green infrastructure”, which in simplified terms includes the greening of areas and buildings.
The idea behind it: The evaporation of water on the surface of plants can have a cooling effect.
According to the researchers, this effect is greater in dry cities than in wetter ones.