Greenland's lakes turn murky, emit CO2 amid climate shifts
Atmospheric rivers have significantly changed Greenland's ecosystem. Lakes once known for their clear, blue waters have now become brown water reservoirs. A recent study revealed that these lakes are beginning to emit carbon dioxide instead of absorbing it.
Scientists from the University of Maine report that approximately 7,500 lakes in the western part of Greenland underwent significant changes following an exceptionally warm and rainy period in the fall of 2022. The high temperatures and rainfall, which replaced snow, caused the permafrost to melt, releasing substantial amounts of carbon, iron, and magnesium into the environment.
Rainfall allowed these elements to enter the lakes, altering their chemical composition. The increase in organic matter stimulated bacterial growth, resulting in the browning of the waters and the emergence of an unpleasant odour. These changes pose a threat to local communities that rely on the lakes as a source of drinking water.
Changes in the chemical composition of the waters affect the biodiversity of plankton. Darker waters block sunlight, leading to a decrease in the number of phytoplankton, which absorbed carbon dioxide. As a result, CO2 emissions from the lakes have increased by 350%.
Atmospheric rivers as a catalyst
Atmospheric rivers are relatively narrow bands where increased humidity occurs. These formations in the atmosphere are responsible for transporting massive amounts of water vapour. This vapour usually originates from the tropics or other high-humidity areas, most often absorbed from the surface of warm oceans. This phenomenon may have been the cause of the intense rainfall in Greenland. Consequently, it could have triggered a chain reaction, destabilizing freshwater ecosystems in the region.
Uncertain future of lakes
Scientists now need to observe the long-term consequences of these changes. It is unknown whether the lakes will return to their original state and how quickly this might occur. Atmospheric phenomena, local ecosystems, and the global climate clearly interact with one another.
The coming years will reveal whether the lakes of western Greenland can withstand the influence of atmospheric rivers or if they will undergo permanent changes. These observations will be crucial for understanding ecosystems' ability to self-regulate in the face of rapid climate changes.
