From carbon sink to source: the stark changes in Arctic lakes

By | September 14, 2023

Cheryl Katz writes:

A family of muskox rumbles along craggy hilltops overlooking the small parade of humans crossing the West Greenland tundra. Ecologist Václava Hazuková, in the lead, sets a brisk pace as we bushwhack through knee-high willow and birch. Leaning forward under an equipment-filled pack nearly half her size, she high-steps over “pillows and mattresses” — hummocks of plants interspersed with troughs of rain-soaked permafrost. The twin blades of a kayak paddle protrude from Hazuková’s pack, pointing to our destination: Lake SS85, a small, clover-shaped lake some two hours away.

Lake SS85 is one of hundreds of lakes dotting this 90-mile-wide fringe of land between the towering Greenland Ice Sheet and the Labrador Sea. For centuries, 85 and its aquatic neighbors have been ice-covered most of the year. But as the climate has warmed, high-latitude lakes — from the northern United States and Canada to Scandinavia and Siberia — have started to thaw, on average, a week earlier and freeze 11 days later than they did a century ago, according to Sapna Sharma, a biologist at York University in Toronto. The rate of ice loss has sextupled over the past 25 years. Northern lake temperatures are rising more than twice as fast as the global lake average, Sharma says. And nowhere is the climate changing faster than in the Arctic.

The boreal forests and unglaciated polar lowlands are Earth’s most lake-rich biome, hosting nearly half of the planet’s lakes by surface area. While precise data are sparse, a 2015 satellite-based inventory estimates some 3.5 million lakes cover a total of around 150,000 square miles in the Arctic. But due to the difficulty of conducting research in the remote north, relatively little is known about how these vast freshwater ecosystems are responding to the sweeping changes underway. [Continue reading…]

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