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Impact of Extreme Climate Events on West Greenland’s Lakes
West Greenland is home to tens of thousands of blue lakes that play a crucial role in providing drinking water to residents and sequestering carbon dioxide from the atmosphere. However, after an unprecedented period of record heat and rainfall in the fall of 2022, approximately 7,500 of these lakes experienced significant ecological changes, turning brown and releasing carbon while suffering a decline in water quality, a recent study reveals.
The research, led by Jasmine Saros, a Fulbright Distinguished Arctic Scholar and Associate Director at the University of Maine Climate Change Institute, sheds light on how extreme weather events can dramatically alter the environment. Published in the Proceedings of the National Academy of Sciences (PNAS), the study indicates that the combination of unusual climate conditions in fall 2022 pushed these Arctic lakes across a disturbing tipping point. Saros noted that the alterations observed by July 2023 typically unfold over centuries, making the changes especially alarming.
Typically, West Greenland experiences snowfall during the fall months, but higher temperatures resulted in increased rainfall instead. This shift not only affected lake water levels but also triggered the thawing of permafrost, which stores large amounts of organic carbon. The thaw released significant quantities of carbon, iron, magnesium, and other substances into the lakes, causing the alarming color change.
Saros, who also teaches paleolimnology and lake ecology at UMaine, highlighted the stark difference between this rapid transformation and the slower browning seen in lakes across the Northern Hemisphere, including those in Maine. “The magnitude and velocity of these changes are without precedent,” she remarked.
As dissolved organic carbon and nutrients from permafrost entered the lakes, they created an environment conducive to bacterial growth, leading to adverse taste and smell in the water, according to Saros. The release of metals can pose health risks as well. By understanding the types and volumes of organic and inorganic materials affecting lake health, local communities can make better-informed decisions about water treatment strategies.
“The influx of dissolved organic material can interact with drinking water treatment processes, leading to the formation of trihalomethanes during chlorination, which may have carcinogenic effects,” Saros stated.
The changes have rendered the lakes murkier, hindering light penetration and negatively impacting plankton biodiversity. This diminished light availability has resulted in a decline in phytoplankton, which typically absorbs carbon dioxide via photosynthesis, while promoting plankton types that break down and release carbon. Instead of acting as carbon sinks during the summer, the lakes have transitioned into carbon sources, exhibiting a staggering 350% rise in greenhouse gas emissions.
Saros explained, “As large amounts of organic carbon washed in from the landscape and became available for aquatic life, the reduced light shifted the ecosystem toward organisms that rely on organic carbon rather than photosynthesis.”
The researchers attributed the extreme level of heat and precipitation to several atmospheric rivers—narrow corridors of concentrated water vapor that can result in heavy rainfall or snowfall when they encounter land. According to the National Oceanic and Atmospheric Administration (NOAA), climate models suggest that frequencies of atmospheric rivers could increase by 50-290% by the century’s end, affecting regions such as Greenland and parts of Western North America and Europe.
Saros emphasized the need for ongoing research and monitoring to understand the potential recovery of these lakes, which would lend insight into lake dynamics and ecological resilience in the region. “Given the overwhelming climatic forces at play, we must determine whether recovery patterns will be consistent across all affected lakes or differ significantly,” she asserted.
This study benefited from comprehensive data collections made possible by consistent water sampling and year-round remote sensor monitoring of the lakes.
“Our findings highlight the importance of long-term observations. My team and I have maintained a consistent dataset for years, which enabled us to quantify these unprecedented climate effects,” Saros explained.
Alongside Saros, the co-authors of the study include several University of Maine Ph.D. students, such as Václava “Vendy” Hazuková, Grayson Huston, Avery Lamb, and Guillaume Bourdin, as well as scientists from various institutions. This collaboration underscores the pivotal role of dedicated research and student involvement in understanding complex environmental challenges.
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