Lake Geneva is getting warmer and hit a record high in 2022, according to a recently published report by the International Commission for the Protection of the Waters of Lake Geneva (CIPEL).
Since 2012, the water temperature at the bottom of Lake Geneva has risen by one degree while the average surface temperature has leapt by 1.2 degrees to 13.6 degrees. Similar changes have been recorded at Lake Constance, Switzerland’s second largest lake – these lakes also fall into French and German territory.
These temperature changes might appear minor. However, they are not. As the surface water warms lakes become more stratified and stagnant. To remain healthy, lakes need their water to mix. Surface water needs to become sufficiently cold and heavy in the winter months to sink and set of a cycle of mixing.
Mixing sends oxygen to the bottom of the lake keeping the the ecosystem in balance. Lake Constance has fully mixed only once in the last 15 years.
If there’s too little mixing, phytoplankton die out and this echos down the food chain. Eventually fish populations take a hit and invasive plant species gain an upper hand, impacting lake biodiversity.
Another threat to lakes is excess animal effluent. Switzerland has more livestock than it’s ecosystem could naturally sustain. Imported animal feed makes the phenomenon possible. But it produces an animal waste problem. Farmers spray it on the ground and some of it runs off into water ways damaging delicate ecosystems.
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CIPEL website (in French) – Take a 5 minute French test now
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