Deepwater renewal in Lake Geneva in light of climate change

Rafael Reiss and his field equipment by Lake Geneva. Alain Herzog/EPFL - Scientists have studied two mechanisms that can help bring oxygen to the depths of a lake - essential for preserving the lake's ecosystem. The classical deepwater renewal caused by surface cooling during winter is becoming less efficient due to climate change, especially in deep lakes. Lakes need to contain a certain level of dissolved oxygen to maintain water quality and preserve their ecosystems. While the upper layers of a lake are typically rich in oxygen, that's not the case for deeper layers; in most lakes, oxygenation of these layers occurs primarily through a process called convective cooling that takes place during the cooler autumn and winter periods. For deep lakes in temperate climates, like Lake Geneva, winters are often not cold enough for this process to occur on an adequate scale, meaning the very deep waters are not affected. The last full-depth convective cooling in Lake Geneva took place in 2012 during a severe cold spell ( CIPEL ).