Lake Geneva’s water temperatures are rising at an unprecedented pace

During winter, the usual process of winter mixing, is when oxygen-rich surface waters blend with deeper waters, which is crucial for oxygenation and biodiversity. 

Marie-Elodie Perga, an expert in lake studies at the University of Lausanne, highlighted the significance, stating, “Overall, we achieve adequate reoxygenation down to 170 meters, but the concern lies beyond that depth. It has been 12 years since the lake bottom experienced reoxygenation through winter mixing.” Urgent measures to mitigate global warming by reducing CO2 emissions are vital.

Professional fishermen are witnessing the effects firsthand, noticing a significant increase in perch catches compared to normal times. Typically, perch spawning occurs from May onwards.

While some species appear to benefit from the rising temperatures, others face threats. The ecosystem of Western Europe’s largest freshwater reserve is undergoing substantial changes. Scientists, alarmed by this phenomenon, installed a platform with hundreds of sensors on the lake five years ago to conduct comprehensive analyses.