When it comes to sea level rise, the melting of ice sheets that float on and along the world’s oceans is a major contributor to climate change.
Melting, as a result of warm and salty seawater seeping under “grounded” sections of ice sheets across the country, and what happens when that combination penetrates deep beneath glacier interiors is less well known.
(Photo: FABRICE COFFRINI/AFP via Getty Images)
How seawater contributes to glacier melt and sea level rise
An assistant professor at the School of Earth and Atmospheric Sciences, Alexander Robel, led a new study published in The Cryosphere that may shed light on the matter. Glaciers could be melting faster than previously thought, according to a new theory from Georgia Tech’s Ice & Climate Group.
Put another way, the article shows that warm seawater can seep beneath glaciers and, as it melts at the bottom of the glacier, can cause forecasts of future sea level rise to be up to two times higher than current estimates.
The researchers found that the ground line (the point where glacial ice meets water) isn’t as impermeable as previously thought, the new study showed.
The study shows that seawater intrusion across flat or reverse-sloped impermeable layers can occur up to 10 kilometers upstream from a glacier’s terminal or baseline, based on mathematical and computer-aided simulations, according to Phys.org.
When salty seawater seeps under glaciers, it can bring heat from the ocean with it. According to researchers, this has the potential to dramatically increase the melting of the glacier floor.
Earle Wilson, a postdoctoral fellow at MIT, and Helene Seroussi, associate professor at Dartmouth College, joined Robel as co-authors of the work.
Also read: New research: Himalayan glaciers are melting rapidly, threatening the water supplies of millions in Asia
Intrusion-induced basal melt
Georgia Tech’s high-performance computing cluster Partnership for an Advanced Computing Environment (PACE) is used in the current study, which expands on a 2020 Wilson-led study that showed how these invasions can occur in the lab.
It’s possible seawater can seep into subglacial meltwater channels, Wilson said, much like ocean water can flow upstream and mix with river water in a typical estuary. If subglacial estuaries are not only possible but also probable, their existence has a profound impact on future sea level rise.
According to Science Daily, a few hundred meters of base melt due to seawater inrush upstream of sea-ice sheet groundlines can lead to projections of 10% to 50% volume loss of sea-ice sheets.
(Photo: OLIVIER MORIN/AFP via Getty Images)
When does seawater inrush occur?
According to Robel, the results of this study show that more observational, experimental, and numerical studies are needed to understand the conditions under which seawater intrusion occurs — and whether it is actually leading to rapid retreat in sea ice cover and rising sea levels will or not in the future.
As a first step, the team will examine measurements from previous field expeditions to see if their theory holds up. They are also working to secure funding for an Antarctic expedition to look for evidence of this type of intrusion in the coming year.
According to Robel, this contributes to important contemporary work trying to determine how rapidly ice sheets are melting in a changing climate and what physical processes are important for these rapid changes.
Related article: Melting glaciers due to global warming are slightly deforming the Earth’s crust, scientists warn
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