Swiss Review 3/2020

Swiss Review / June 2020 / No.3 8 Adapting urban development to climate change Extreme summer heat is harmful to public health. The mortality risk increases markedly during heatwaves. Hundreds of people in Switzerland died from the extreme tempera- tures in 2003 and 2015, with the elderly in urban areas particularly affected. Such heat- waves will be longer, hotter and more frequent due to climate change. The challenge for urban developers is to ensure that towns and cities continue to offer a good quality of life in a warmer climate. The Federal Office for the Environment (FOEN) drew up guidelines for adapting urban development to climate change in a 2018 report that uses examples in Switzerland and abroad to illustrate how the urban heat island effect can be reduced. How- ever, none of this will stop the rise in summer temperatures. Excessive CO2 emissions are the root cause of climate change. A massive reduction in greenhouse gases – as prescribed in the Paris climate agreement – is the only way to counter global warming. (TP) Link to the FOEN report “Hitze in Städten” (in German) : ogy.de/stadthitze Focus increase in the average number of 30°C days from20 to 44. “We need to stop heat from smothering the entire city,” says the head of Zurich’s envi- ronmental and health protection department, Christine Bächtiger. Specifically, this means minimising asphalt and other forms of paving, be- cause paved surfaces are liable to heat their surroundings from all the solar radiation that they absorb. The au- thorities also want to relieve parts of the city that are densely populated or have a high proportion of older in- habitants who find it harder to cope in hot weather. Other options include expanding the network of paths and parks as well as enlarging less heat- prone areas of the city. Zurich has a favourable geography compared to other places, with three quarters of the city benefiting from the cool air that flows down at night-time from the wooded slopes of Zürichberg, Käferberg and Uetliberg. To preserve this natural ‘cold air system’, Zurich’s urban planners intend to keep cer- tain air corridors free and ensure that new builds do not exceed a certain height. The authorities in Basel have also conducted an analysis that maps the city’s ‘heat islands’, ‘green lungs’ and prevailing air flows. Spatial planners and architects used these findings to build the Erlenmatt district from scratch, positioning the buildings in such a way as to ensure that fresh air continued to blow in from the Wie- sental valley. Constructed according Zürich / BD / AWEL / Abteilung Lu� wser (h�p://maps.zh.ch) Air temperature in and around Zurich at 4 a.m. <=22º 23º 22º 24º 25º 26º 27º 28º 29º 30º 31º 32º >= 32º <=13º >= 21º 13º 14º 15º 16º 17º 18º 19º 20º 21º modell Kanton Zürich: Lu�temperatur in °C um 04 Uhr nalysekarte / Nachtsituation / Lufttemperatur Zürich / BD / AWEL / Abteilung Lu� wser (h�p://maps.zh.ch) > 16.5 - 17 > 16 - 16.5 > 15.5 - 16 > 18 - 18.5 > 17.5 - 18 > 17 - 17.5 > 19.5 - 20 > 19 - 19.5 > 18.5 - 19 >= 21 > 20.5 > 20 - 2 > 13.5 - 14 > 13 - 13.5 <= 13 > 15 - 15.5 > 14.5 - 15 > 14 - 14.5 Air temperature in and around Zurich at 2 p.m. These two images show temperatures that are now typical of calm high-pressure summer weather in Zurich. Source: canton of Zurich; Office of Waste, Water, Energy and Air; maps.zh.ch (GIS browser)