Sylvain Allemand // Credits: BERTRAND BODIN / ONLY FRANCE / ONLY FRANCE VIA AFP 1:56 p.m., February 26, 2024, modified at 1:57 p.m., February 26, 2024

Lakes are also victims of climate change.

Lake Geneva, for example, is warming four to five times faster than the oceans.

Even well nestled in the Alps, Western Europe's largest fresh water reserve is finding itself battered by increasingly mild temperatures.  

Will Lake Geneva become pleasant for swimming?

Western Europe's first freshwater reserve of glacial origin is heavily impacted by global warming, according to a study by the International Commission for the Protection of Lake Geneva Waters (CIPEL).

In their report, the experts indicate that the temperatures of the Franco-Swiss lake are increasing four to five times faster than those of the oceans.

In 2022, the waters on the surface of Lake Geneva had an average temperature of 13.6 degrees.

The thermometer had not displayed such figures since 1990.

A situation due to the increase in mild winters in the region which prevent surface waters, partly fed by melting glaciers, from mixing with colder waters from the depths.

In addition, the winter period is the only time of year when the surface and the bottom can mix under the effect of cold and wind.

"This phenomenon, called 'winter mixing', is characterized by the depth of mixing which separates the mixed surface layer and the bottom layer which has not assimilated with the surface water. The more severe the winter, the more the mixing depth is getting closer to the bottom of the lake” indicates CIPEL. 

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Warming with multiple consequences 

The repetition of incomplete mixing over the last ten years has led to an increase in the temperature at the bottom of the lake (+1.1°C since 2012) as well as a decrease in the oxygen content.

“The warming of the lake bottom and its deoxygenation represent a risk of asphyxiation for living organisms at depth,” warns the commission.

Historically, the largest body of fresh water in Western Europe is a formidable area of ​​biodiversity.

Rising temperatures cause less food for local wildlife, which subsequently struggles to reproduce.

Deteriorating water quality is not only detrimental to wildlife.

Indeed, the waters of the lake provide water for the French and Swiss.

Global warming allows the massive proliferation of algae and bacteria.

An increase making water treatment more expensive is necessary to make water safe for consumption. 

A trend that should continue 

Considered one of the jewels of the Alps, Lake Geneva is also a victim of its location.

In 2023, the UN sounded the alarm regarding climate change in the mountain range.

According to the organization, the region's glaciers are melting at a spectacular rate, as the Alps are warming twice as fast as the rest of the planet.

A trend that is expected to continue until 2060, according to United Nations experts.

A not very encouraging prospect for lovers of Lake Geneva.