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Extreme Weather Transforms Lakes in Western Greenland
Context:
A recent study published in Proceedings of the National Academy of Sciences has revealed alarming changes in over 7,500 lakes in western Greenland, driven by extreme weather events in 2022.
What Happened to the Lakes?
- Transformation in Record Time: The lakes, once crystal blue, turned brown, began emitting carbon, and suffered a drop in water quality in just a few months—an unprecedented rate of change.
- Cause of the Change:
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- In 2022, Greenland experienced unusual weather: rain instead of snow due to warmer temperatures, and permafrost thawing.
- The thawed permafrost released significant amounts of organic carbon, iron, magnesium, and other elements into the lakes.
- The extreme weather events were driven by atmospheric rivers—narrow regions in the atmosphere that transport large amounts of water vapour, leading to intense precipitation and heat.
- As global temperatures rise, atmospheric rivers are expected to become 50–290% more frequent by the end of the 21st century in regions like Greenland, North America, and Europe.
Impact on Lakes and Ecosystems
- Water Quality Degradation: The influx of carbon and other elements changed the physical, chemical, and biological properties of the lakes. By July 2023, the lakes had altered in colour, odour, and taste, and their water quality had deteriorated.
- Increased dissolved organic material in the water could lead to the formation of carcinogenic chlorination byproducts, like trihalomethanes, during water treatment.
- Environmental Consequences: The change in colour decreased the amount of sunlight penetrating the lakes, affecting phytoplankton, which are crucial for carbon dioxide absorption through photosynthesis.
- Shift to Carbon Sources: As light reduced, organic carbon pathways became more dominant in the ecosystem, causing a shift from a carbon sink to a carbon source. The lakes’ emissions of carbon dioxide increased by 350%.
Implication for Global Climate
- Global Carbon Cycle Disruption: The findings contribute to concerns about the stability of Earth’s natural carbon sinks (oceans, forests, soils). As these sinks either stop absorbing carbon or become carbon sources, atmospheric carbon levels could rise significantly.
- Carbon Absorption Decline: A related study found that carbon absorption by land (forests, plants, and soil) in 2023 was at its lowest (Only 0.23–0.65 gigatonnes) since 2003, further emphasising the urgency of the situation.
- A Warning for the Future: The study highlights the vulnerability of Arctic ecosystems and the urgent need for global action to mitigate climate change and protect these vital water bodies.
