the water temperature of Lake Geneva increases 4 to 5 times faster than the oceans

This represents a threat to ecosystems, but also to French and Swiss local residents.


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The Jet d'Eau of Geneva (Switzerland) on Lake Geneva.  (STÉPHANE MILHOMME / RADIO FRANCE)

It’s not just the air and oceans that are warming. Lakes are also suffering from global warming and Lake Geneva is no exception. The largest fresh water reserve in Western Europe is warming four to five times faster than the oceans, warns the International Commission for the Protection of the Waters of Lake Geneva (Cipel) in its latest report published on February 12.

Because it is fed by melting glaciers, Lake Geneva is still considered “a little chilly” in the opinion of bathers. But this could change. The average annual temperature of surface waters was measured at 13.6 degrees in 2022, which is a record since 1990. In 2022, surface waters showed 13. 6 degrees on average. This is unheard of since 1990. The cause: the increase in mild winters which prevent surface water from mixing with that at the bottom.

“Four degrees is just impossible, unmanageable”

And the trend is not going to stop any time soon. The Alps are warming twice as fast as the rest of the planet, recalls Marie-Elodie Perga, professor of limnology – the study of lakes – at the University of Lausanne: “Obviously, if we get to plus four degrees, there will be no adaptation possible but the lake will ultimately be the least of our concerns compared to everything that will fall on us in terms of food , water supply… So let’s all agree, four degrees is just impossible. Unmanageable, in any case.”

A warmer Lake Geneva means wildlife that lacks food: species of fish, like the féra, which are no longer able to reproduce and bacteria which proliferate, making water treatment more costly for the million people. French and Swiss people drinking lake water. The only solution to limit the warming of Lake Geneva: limit warming altogether.

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