The cooling effect of urban vegetation contributes to a pleasant and healthy climate in our cities, especially in times of global warming. Sensitive people in particular (the elderly, the sick, small children) often suffer from periods of summer heat if the presence of enough urban vegetation does not reduce the impact of urban heat islands.
The indicator for the ecosystem service "climate regulation in cities" combines the supply of cooling effects from vegetated areas in the city with the demand from the resident population. Based on the land cover, a specific cooling capacity value is determined from the tree canopy and ground cover, area size and climate region; this cooling capacity is listed as an ecosystem condition indicator. This indicator addresses conditions that typically exist on clear days without cloud cover, i.e. days on which the thermal load for humans is high and consequently the effects on human well-being and health are high. Cooling effects at night or during wind ventilation are not included here.
The climate regulation in cities indicator results from a comparison between the cooling capacity of urban neighbourhoods and the number of inhabitants. All cities with more than 50,000 inhabitants that lie within the "functional urban areas" according to the Copernicus Urban Atlas are analysed.
In 2018, 76 % of the population in the 165 German cities analysed can benefit from high or very high cooling capacities in their immediate living environment. In 37 cities, more than 85 % are even supplied with good to very good cooling capacity through green infrastructure. No other time periods are yet available and therefore no trends can be derived.
Original methodics paper: Zardo, L., Geneletti, D., Pérez-Soba, M. und van Eupen, M. (2017): Estimating the cooling capacity of green infrastructures to support urban planning. In: Ecosystem Services (26), 225–235. doi:10.1016/j.ecoser.2017.06.016.
The indicator calculation was applied to Germany by the following steps:
- Identification of the cities to be analysed (over 50,000 inhabitants whose official municipal boundaries lie within the functional urban areas of the Urban Atlas, 2018)
- Assignment of land cover types (sealed, open ground, heterogeneous, grass, water, forest)
- Calculation of tree canopy cover (in per cent from various data sources)
- Calculation of area size and differentiation of areas over and up to 2 hectares
- Determination of the possible cooling effect taking into account the distance
- Determination of the average cooling capacity for each city
- Determination of the supply of the inhabitants with cooling capacity for each city.