In a groundbreaking study, scientists have revealed that thousands of crystal-clear Greenland lakes have turned brown and started emitting carbon dioxide due to global warming. The tipping point occurred as the lakes’ permafrost melted under intense heat and heavy rain, releasing stored carbon into the water. This shift marked the first time in centuries that these lakes were no longer absorbing CO₂ but instead releasing it into the atmosphere.
The change began in fall 2022 when global warming turned snow into record-breaking heat waves and thawed the frozen permafrost beneath the ice sheets, which stores vast amounts of carbon. The heavy rains washed this material into the lakes, turning them from blue to a murky brown. As the lakes darkened, less sunlight could penetrate the water, harming plankton life that relies on photosynthesis. While plankton absorbed CO₂ during the summer, their numbers began declining as they broke down the stored carbon, causing the lakes to emit more of it.
The transformation was so abrupt and severe that researchers have never observed such changes in other parts of the Northern Hemisphere or even within Greenland itself before this tipping point. The study’s lead author, Jasmine Saros, emphasized that the rate of change was unprecedented. The findings were published in the journal PNAS earlier this week.
The lakes now provide invaluable drinking water for Greenlanders, but their brown tint poses a growing threat as they continue to emit CO₂. The influx of dissolved organic matter and nutrients could also have negative impacts on water supplies, potentially causing bacteria growth that affects water taste, odor, and health. Some scientists fear the lakes may remain brown long after this study concludes.
Patrick Pester is a trending news writer at Live Science, with a background in wildlife conservation. He holds a master’s degree in international journalism from Cardiff University.
Source: https://www.livescience.com/planet-earth/climate-change/catastrophic-tipping-point-in-greenland-reached-as-crystal-blue-lakes-turn-brown-belch-out-carbon-dioxide