Five lesser-known effects of extreme heat in Switzerland

Extreme heat is not measured by the thermometer alone. An analysis by SWI swissinfo.ch written by Luigi Jorio gathers some of the less visible consequences of heatwaves in Switzerland.

The first concerns electricity. On 26 June Axpo shut down two reactors at Beznau, in Aargau, when the water of the Aare reached 25 degrees. The same plant had already suspended production temporarily the previous July. In France 3 of 57 reactors were deactivated and another 8 reduced output. According to EDF estimates, climate change will cut reactor availability by around 2% a year by 2050.

The second concerns the railways. Heat expands the steel of the rails and deforms tracks and overhead lines. In June the Swiss Federal Railways recorded heat-related faults in infrastructure and rolling stock, while in France dozens of trains were cancelled on high-speed lines. The railways now spray the tracks using tank wagons and plan to replace wooden sleepers with concrete ones, which resist heat better.

Drinking water, vegetables and ticks

The third effect concerns drinking water. Swiss lakes reached temperatures up to 7 degrees above the average for 1983 to 2024. The association managing water from Lake Constance warned that heat encourages the proliferation of legionella. The law sets 25 degrees as the limit not to be exceeded, but that value can no longer be respected everywhere.

The fourth concerns the shopping basket. During heatwaves farmers have to irrigate more. Coop expected effects on prices in the following weeks, while Migros initially applied no increases. The Swiss Union of Vegetable Producers called for adequate compensation for the extra irrigation effort. Potatoes risk remaining unsellable if they fail to reach the size required by retailers.

On this point the question is not only technical. The cost of water and of the extra work falls either on those who produce or on those who buy, and how it is shared depends more on agreements with the large retailers than on the climate.

The fifth effect points the other way. In June cases of tick-borne encephalitis fell to 1.18 per 100,000 inhabitants, against 1.46 the previous year. Lyme disease went from 28.45 to 23.16 cases per 100,000 inhabitants. Ticks, in fact, avoid conditions of extreme heat.