Scientists Find Rate Of Submarine Melting At LeConte Glacier (AK) Up To 100X Greater Than Thought
The LeConte Glacier in southeast Alaska is a 21-mile long fast-flowing tidewater glacier, which terminates abruptly in a fjord––spilling its contents into the ocean. The glacier sheds ice from its 200-meter face in calamitous calving events when large blocks of ice drop into LeConte Bay. Researchers seeking to collect data on the glacier’s submarine melt rate needed a way to get close enough to the terminus to collect the data they needed—the solution: a fleet of robotic kayaks sent into waters too dangerous for human researchers to enter.
The November 2019 study, which was published in the journal Geophysical Research Letters, was led by Rebecca Jackson, an assistant professor of physical oceanography at Rutgers University, and a team of researchers from Oregon State University, University of Alaska Southeast, University of Oregon and University of Alaska Fairbanks. Tidewater glaciers are glaciers that reach all the way to the ocean. At their border with the sea, they melt either through calving or through submarine melting.
Submarine melt matters because it is a significant contributor to glacier melt and is sensitive to rises ocean temperature and shifts in ocean circulation. It’s also more difficult to observe directly than surface melt because it occurs on the underside of glaciers. It can take place through two processes. The first is more easily detectable and comes from the drainage of freshwater discharge due to upstream melt on the glacier. It creates fast-moving plumes of water entering the ocean at the glacier’s terminus. The second type of submarine melting is the slower and harder to measure process of ambient melting where a glacier melts directly into the sea.
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The data gathered by the autonomous kayaks show that ambient melting is a significant contributor to total melting at a glacier’s terminus and represents a large part of the total submarine melt flux. It revealed that ambient melt has been underestimated by a factor of up to 100. “We need these types of measurements being performed in front of several other glaciers in different regions before making a new statement about the general pattern or magnitude of submarine melt and its effect on sea-level rise,” Nick said. This finding increases scientists’ understanding of submarine glacier melt and opens the door for further research to establish a generalizable melt parameter for modeling ocean‐glacier interactions. As scientists’ understanding of glacier melt dynamics improves through studies like this one, they are one step closer to being able to generate predictive models on critical issues like sea-level rise with greater accuracy.
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https://glacierhub.org/2020/04/14/robotic-kayaks-discover-high-rates-of-underwater-glacier-melt/