Dark algae are spreading across the Greenland ice sheet as snow retreats. Their dark color causes ice to absorb more heat from the sun, accelerating melting, and according to a new study, the harsh conditions atop the ice sheet will do little to slow their advance.
Researchers used advanced imaging to examine individual cells of the algae Ancylonema, finding that they can thrive in places where nutrients are scarce. “They don’t require large amounts of external nutrients to grow, which means that as the ice sheet continues to melt and expose more bare ice, these algae are well-positioned to expand their coverage,” said study coauthor James Bradley of Queen Mary University of London.
In the summer of 2017, algal blooms on the western edge of Greenland caused the ice to shed around 10 percent more water than it would have otherwise, an alarming figure given that Greenland is the biggest source of meltwater fueling sea level rise globally.
“Understanding these algal blooms is critical for predicting future ice sheet behavior and sea level rise,” Bradley said. He said the findings, published in Nature Communications, suggest that as snow further retreats, “we are likely to see a self-sustaining cycle where more algae lead to more melting.”
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