While meteorologists have referred to this summer as “record-breaking”, with temperatures reaching 40C, the recent heatwave is a not new phenomenon per se.

With temperatures gradually rising for years due to climate change driven by the global warming, Swiss cities have become the so-called “urban heat islands” — densely populated zones where buildings and paved roads trap and absorb the heat and release it into the air.

READ MORE: 40C: Switzerland set for another heatwave

According to a report by RTS public broadcaster, “the effect of heat islands is greater in areas with a high built-up density and fewer green spaces”.

In Geneva, for instance, the districts of Pâquis, Plainpalais, Eaux-Vives, and Pont-Rouge are particularly affected.

In Zurich, the densely populated city centre and the area around the train station are the two hottest spots.

This Youtube video explains where Zurich’s urban heat islands are located.

How do the two cities counteract the effect of these heat bubbles?

According to climatologist Martine Rebetez, the best way to generate coolness is “an urban forest with vegetation on the ground and tall trees so as to create a continuous canopy”.

In Geneva, for instance, 21 percent of the urban zones have these kind of canopies, and the city’s objective is to increase this coverage to at least 25 percent by 2030.

Between 2020 and 2022, 900 trees, have been planted in Geneva specifically for this purpose.

However, as the TSR report points out, this coverage is unequal and seems to be income-based.

“In Florissant, the second-highest income district of the municipality of Geneva, more than 30 percent of the territory is under foliage. In Pâquis, on the other hand, where the median income is much lower, the canopy barely covers 5 percent of the area”.

What about Zurich?

Aside from green areas already in the city, municipal authorities are not only planting new trees but are also replacing those that had to be cut down due to damage.

A new feature is a giant fogger that was recently installed on the Turbinenplatz, one of the largest squares in the city. As soon as the thermometer passes the 30C mark, it sprinkles fine particles of water, cooling the air by up to 10C.

“The contribution of trees to the climate of the city remains unequaled”, said Simone Brander, head of Zurich’s public works at during the inauguration of the fogger.

“Sometimes technical innovations like this artificial cloud can serve as a sensible addition to reduce heat as well.”

READ MORE: How to keep your cool during Switzerland’s heatwave