Wednesday 20 January 2021

Greenland melting likely increased by bacteria in sediment

Bacteria are likely triggering greater melting on the Greenland ice sheet, possibly increasing the island's contribution to sea-level rise, according to scientists. That's because the microbes cause sunlight-absorbing sediment to clump together and accumulate in the meltwater streams, according to new study. The findings can be incorporated in climate models, leading to more accurate predictions of melting.

The Greenland ice sheet covers about 656,000 square miles -- most of the island and three times the size of Texas, according to the National Snow & Ice Data Center. The global sea level would rise an estimated 20 feet if the thick ice sheet melted.

With climate change, sea-level rise and coastal storms threaten low-lying islands, cities and lands around the world.

Most scientists ignore sediment in glacial streams that form on top of the Greenland ice sheet as meltwater flows to the ocean, but the Rutgers-led team wanted to find out why they accumulated so much sediment. In 2017, scientists flew drones over an approximately 425-foot-long stream in southwest Greenland, took measurements and collected sediment samples. They found that sediment covers up to a quarter of the stream bottom, far more than the estimated 1.2 percent that would exist if organic matter and cyanobacteria did not cause sediment granules to clump together. They also showed that streams have more sediment than predicted by hydrological models.


Sasha Z. Leidman, ├ůsa K. Rennermalm, Rohi Muthyala, Qizhong Guo, Irina Overeem. The Presence and Widespread Distribution of Dark Sediment in Greenland Ice Sheet Supraglacial Streams Implies Substantial Impact of Microbial Communities on Sediment Deposition and Albedo. Geophysical Research Letters, 2020; DOI: 10.1029/2020GL088444

Posted by Dr. Tim Sandle, Pharmaceutical Microbiology Resources (

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