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The Transformation of Greenland’s Lakes: A Rapid Change in Ecology

Every summer since 2011, Professor Jasmine Saros has dedicated her time to studying the freshwater ecosystems of West Greenland. As an expert in lake ecology at the University of Maine, her annual research trips are essential for tracking changes in these vital habitats. During her routine data collection in 2022, the ten lakes she typically studies appeared mostly stable, displaying the gradual impacts associated with climate change. However, the following summer revealed a startling transformation.

In 2023, upon her return, Saros found the lakes dramatically altered. “You could see it right away,” she observed. The once pristine blue waters that allowed the rocky beds beneath to be seen clearly had turned a murky brown. Initially, the scientists speculated that only a single lake was affected, but soon realized that all ten had undergone this unexpected change. “There was this major transformation that occurred across all the lakes in the landscape,” Saros remarked, expressing her astonishment.

Typically characterized as a relatively dry tundra, West Greenland features a myriad of lakes within its landscapes. Saros and her research team estimate that around 7,486 lakes exist in her study area alone, many of which are likely experiencing similar browning, indicating a wider ecological shift.

This change in color has profound implications beyond mere aesthetics; it signifies a fundamental shift in the lakes’ ecology, as outlined in a study published in the Proceedings of the National Academy of Sciences. The findings reveal a staggering 90% loss in microbial biodiversity, an increase in dissolved iron by 1,000%, and a transformation from carbon dioxide sinks to sources, leading the ecosystem to emit rather than absorb this greenhouse gas.

The dramatic alterations stem from particularly warm and wet conditions during the autumn of 2022, which resulted in significant permafrost thawing and the subsequent influx of organic materials and metals into the lakes. “This extreme autumn season essentially led to a big flushing of that material into lakes,” Saros explained. Moreover, the interaction among lakes increased, causing them to mix and spread these changes over a broader area. The additional heavy rain and warmth experienced in July 2023 contributed to this evolving state. Satellite images suggest these phenomena extend beyond the lakes, with the surrounding land also showing signs of increased greenness.

Although lake browning has occurred throughout Earth’s history in response to ecological shifts, such a rapid transformation is unprecedented. Typically, similar changes would require centuries to manifest. In Saros’ view, the acceleration observed in West Greenland—where natural processes might take a millennium—has become alarmingly rapid.

Past patterns, such as a similar precipitation event in September 2003 that did not result in major ecological shifts, highlight the unique conditions in today’s climate. Climate change has been linked to an increase in the frequency of heatwaves and atmospheric rivers in the Arctic, with projections suggesting significant increases in these events by the end of the century.

The question of whether these lakes can revert to their previous states remains uncertain. Saros speculates that a series of dry years might help restore clarity, but increased evaporation and contamination from past changes complicate this possibility. “It’s hard to predict,” she conceded, expressing concern that the current trajectory of climate change may make a return to blue lakes highly unlikely.

The immediate implications of these changes extend directly to the local communities in Greenland, many of which rely on lake water for drinking. The evolving ecosystem may introduce health risks due to potential metal toxicity, highlighting the necessity of infrastructure investments for water treatment solutions. While Saros has shared her research findings with community members, the future steps remain unclear.

Source
www.popsci.com