Temperatures across Europe have increased considerably, to over 40 degrees Celsius in some cases, which not only causes infrastructure problems in countries that are ill-prepared for extreme heat, but also human casualties.

Sometimes, staying indoors isn't really a better choice, especially if working in an environment that is not properly ventilated, as Politico reports that temperatures in some warehouses can go higher than 46 Celsius.

Big cities can also be considered quite literally "hotspots", as all the concrete, metal and asphalt radiate the already high levels of heat.

Humidity plays a big role in the way we feel temperature, as if there are 32 degrees Celsius outside, but humidity is rated at 70%, the heat index is at 41 degrees Celsius, nearly 10 more than what the Mercury reports in thermometers.

Birgit Georgi, a climate adaptation expert who advises the EU's Urbact program, said that "the accumulation of warmth in heat islands is so intense — and the materials' release of heat is so slow — that these areas can't manage to cool down at night. As a result, people living in these areas have to deal with constant, unbearably high temperatures."

Green infrastructure, the potential solution against heat waves

There is a way we can make cities safer, experts say, that is by investing in a lot of green spaces.

"People living in cities that have invested in green infrastructure — parks and gardens, green façades, sustainable cooling and water management strategies — are less likely to be affected", she added.

Vienna, for example, is one of the cities that is best prepared in case of heat waves, as the city started developing a strategy for such events back in 1999.

In 2018, it became one of the first European cities that made a strategy to detect and fight urban heat.

Jürgen Czernohorszky, the city's executive councilor for climate, explained that "we knew Vienna was likely to be hit hard by the climate crisis because of its geographic situation, with scientists predicting temperatures would rise by five to six degrees within the next two decades. We're using our planning scheme to work with districts on a transition aimed at preventing heat islands."

Some of the measures implemented by city officials include subsidies for green roofs and façades and improvements in the public infrastructure, such as mist sprinklers that activate automatically whenever it gets hot and special bike routes.

These have the role to discourage people from traveling by car and, instead, opt for the more eco-friendly alternative that doesn't produce heat.

Paris also followed a similar strategy in 2019, when authorities unveiled a "cool island" network including parks, museums and public buildings where people can take cover from the burning sun.

Almost all Paris-dwellers live within seven minutes or so from such oasis and they can locate them via an app.

Other cities, such as Nuremberg and Mainz, are looking to grow grass on tram lines in order to cut on the heat these vehicles generate.

These are just some of the measures authorities can take to reduce heat levels inside cities and make living in them during heat waves more bearable for everybody.

Cutting the number of fossil-powered vehicles that travel through the streets of busy cities, encouraging alternative transportation methods and building on green infrastructure, such as parks, are some of the best ways to fight extreme heat.