HEAT IN THE CITY
Cities are particularly affected by rising temperatures. Asphalt, concrete and other sealed surfaces store heat during the day and take a long time to cool down. This creates heat islands in densely built-up areas: places where heat accumulates due to a lack of air circulation – and where there is hardly any cooling even at night.
HEAT MANAGEMENT IN CITIES
Cities like Zurich are responding to increasing heat stress with targeted measures. The focus is on protecting existing cold air systems and reducing heat islands. Water and green spaces are particularly important in this regard due to their cooling effect. They act like natural air conditioning systems. They cool the air through evaporation – either via the leaf surfaces of plants or directly via open water areas.
Trees and other plants provide shade, thereby lowering the temperature on sealed surfaces. This leads to a noticeable reduction in stress – for climate, nature and people.
EXAMPLE OF HEAT MITIGATION IN THE CITY OF ZURICH: ALTO ZÜRRUS PILOT PROJECT
In addition to the trees, an artificially generated spray mist over Turbinenplatz in Zurich West provided cooling on hot days until the end of 2023. It was found that mist close to the ground had the greatest effect, but even more important was the cooling provided by the trees and their shade. People enjoyed the spray mist.
Source: City of Zurich, photo: Tabea Vogel
IT’S GETTING HOTTER!
Global warming is making Switzerland warmer. A warming of 2 °C (GWL 2.0, Global Warming Level) would mean about 3.6 °C warming in Switzerland. With the measures currently in place and those planned, we will reach this level of warming by 2050, and by 2040 if we continue to rely on fossil fuels without protecting the climate. By 2065, the world will be 3 °C warmer (GWL 3.0; Switzerland approx. 4.9 °C) if we continue to rely on fossil fuels without protecting the climate. With the measures currently planned to reduce global emissions, we will reach 3 °C warming by the end of the century.
The maps show how this will affect the increase in the number of hot days (temperatures of at least 30 °C) in cities. In Zurich city centre (Kaserne), for example, the number of hot days is expected to triple compared to the reference period (1991–2020): from an average of 16 days to 32–58 days per year. Which of the possible scenarios will occur depends on the climate protection measures implemented worldwide and the associated global temperature rise.
Sources: IPCC, Climate Action Tracker (as of 2025)
Illustrations: MeteoSwiss and ETH Zurich, Climate CH2025 (modif.)
Measures against heat in the city: in site development, on buildings and in outdoor spaces.
Sources: Canton of Zurich, Umsicht – Agency for Environment and Communication (modif.); Zug Estates AG – Rotkreuz, Suurstoffi site (modif.)