A new study suggests bacteria may hasten ice loss by increasing meltwater in Greenland's ice sheet. Not only will this significantly contribute to rising sea levels, but there are unknown repercussions as well.
Greenland Ice Sheets
According to the National Snow & Ice Data Center, ice sheets are masses of glacial land more than 50,000 square kilometers. Together, ice sheets in the Antarctic and Greenland make up 99% of freshwater ice on earth.
During the Ice Age, ice sheets covered most of North America and Scandinavia. These form in areas where snow frequently falls in winter and melts entirely over the summer. Thousands of years of snow pile up into thick masses that grow thicker and denser over the years.
Few know that ice sheets are in perpetual motion, slowly flowing downhill due to its eight. Ice moves relatively faster in outlets called glaciers, ice shelves, and ice streams near the coast. As long as ice sheets accumulate the mass of snow it losses at sea, it maintains stability.
Scientists estimate that if the Greenland Ice Sheet melted, a global increase of 6 meters of sea level would occur. And if the Antarctic Ice Sheet melted, sea levels would increase by 60 meters.
Together, the Greenland and Antarctic ice sheets influence weather and climate. Plateaus of high-altitude ice caps change storm tracks and create downslope winds of cold to the surface.
Also, the blackened layer of ice in Greenland and Antarctica contain records of Earth's climatic changes.
Bacteria Hastensthe Melting of Greenland Ice Sheets
A study published in Advancing Earth and Space Science used bathymetry, drone imagery, and hydrology measurements from 2017 to study the extensive supraglacial stream networks in the Greenland Ice Sheet.
Here they discover that 24% of the channel was covered by sediment. Using calculations and theoretical water depth measurements, researchers saw that microbial growth within the sediment hastens extensive flocculation and creates large aggregates that easily separate.
Without flocculation, sediments would flush out of supraglacial streams and have significantly higher albedos.
The research concludes that superglacial stream albedos may be sensitive to changes in temperature, stream chemistry, and meltwater supply.
"These streams can be seen all over Greenland, and they have a brilliant blue color, which leads to further melting since they absorb more sunlight than the surrounding ice," says Sasha Leidman, lead author of the study.
"This is exacerbated as dark sediment accumulates in these streams, absorbing even more sunlight and causing more melting that may increase sea-level rise," she continues.
The Greenland Ice Sheet covers 656,000 square miles throughout most of the island. If it were to melt, experts predict that it could raise the global average of seal-levels by 20 feet.
Researchers discovered that the only way for such sediment to grow in the streams was if bacteria growth was abundant that caused it to clump into balls 91 times its original size. They add that the sediment aggregation process started earlier than human history.
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