Thwaites Glacier Collapse and Sea Level Rise

A possible collapse of the Thwaites Glacier would cause global sea levels to rise by about 65 centimeters. Two studies published in the journal Nature They reveal melting patterns according to the topography of the area and describe how interactions between ice and ocean play a role.

Facing the rise of sea ​​level that follows the progressive dissolution of the polar ice, by the heating Globally, scientists are diving into the ocean to find out how this melting occurs and enable some preventative (or corrective) action. mitigation). One of these missions was revealed today, through two articles about the Thwaites Glacier, published in the magazine Nature.

Thwaites is the name of a huge glacier in Antarctica that flows into the iconic Amundsen Sea. On this large glacier in the West Antarctic region —which is the size of the United Kingdom or the size of the state of Florida in the United States— the MELT projectthe joint study of an international team, formed by two groups of scientists, one British and one American.

Investigation into possible collapse of Thwaites Glacier

Investigating one of the Antarctic glaciers that dramatically changes its constitution was imperative. In that case, much of the ice sheet is below sea level, making it susceptible to rapid ice loss, which could raise global sea levels by more than half a meter over the next few centuries.

Consulted by SINC, the oceanographer Peter Davisof British Antarctic Survey (BAS), and one of the authors of the article, explains: “The thwaites glacierin West Antarctica, is buried below sea level in a bedrock that dips inland and is therefore subject to the potential risk suffer a collapse fast and irreversible. In his own words, such a collapse could raise sea levels by a magnitude that “would have substantial consequences for the coastal populations from Europe and around the world.

Thus, according to the scientist who led the British team, “we need understand the processes that are driving this glacier’s retreat in order to accurately predict the rate and extent of future sea level rise.”

Thwaites Glacier Collapse: Crevasses, Ladders and Natural Slides

Thwaites Glacier is one of the ice and ocean systems which transforms faster. In fact, the part where the glacier connects with the land, in the seabedseparated some 14 kilometers since the late 1990s.

“Landline melting below the solid shelf (in the floating extent of the glacier) is a key process controlling the contribution of glaciers to future sea level rise,” argues Davis.

It was in this area bordering the glacier with the seafloor that the MELT team made the observations —more precisely, under the eastern Thwaites ice shelf—, to understand how the ice sheet interacts with the ocean in that critical sector.

Processes under floating ice

There, scientists were able to witness the different processes that occur under the floating ice and verify that although there is a lower than expected dissolution below much of the shelf, the ice gets thinner faster on cracks and crevasses, so the glacier continues to retreat. Still, the results show that the current rate of melting is slower than many computer models currently estimate.

This is how the British researcher describes it: “We observed that the flat ice surfaces they reduce the melting rate, but it is strongly increased on sloped or vertical ice faces”.

Sometimes, according to the study, melting generates a topography in stair shapeat the bottom of the platform, therefore, in these strips, the ice melts faster.

The author points out that “these complex ice-ocean interactions are not currently incorporated into climate models, which increases our uncertainty in future sea level projections”.

With the help of an underwater robot

magazine articles Nature they provide a clearer picture of the changes transforming the glacier underneath. To test for these mutations, each of the teams took a different approach to the glacier belt that connects with the land.

Davis describes it this way: “By collaborating with britney schmidtwe combine our experience in accessing the ocean, through drilling on the eastern Thwaites ice shelf, with the technology contained in its underwater vehicle, known as Icefin. This has given us an unprecedented ability to explore the complex ice-ocean interactions that occur in that land connection sector.”

At the end of 2019, BAS scientists carried out measurements in the ocean, through a 600 meter well depth, about two kilometers from the ground connection line, thanks to a hot water drill. These were compared with melt rate observations made at five other locations below the shelf.

In a period that lasted about nine months, they were able to verify that, in that sector, the sea water became hotter and presented greater salt concentrationbut the ice base melted, on average, between 2 and 5 meters per year (lower value than expected in the previous model).

glacier in trouble

About these discoveries, the author points out that the results were “a surprise” and, however, the glacier is still “in trouble”. If an ice shelf and a glacier “are in balance,” the continent’s ice will compensate for what melts or breaks off, but scientists have found that even though the ice is melting at a slower rate than estimated, “there is still one fast rewind of the glacier”, which makes them predict that “it doesn’t take much to unbalance it”.

In turn, Dr. Britney Schmidt, from Cornell University, USA, and her team the robot through perforations carried out by the British group. In this way, they were able to access these deep areas of connection to the earth that were previously almost impossible to inspect.

Thanks to Icefin’s observations, they discovered, under the ice shelf, that these ladder-like formations (or terraces and cliffs) melt quickly. And this is particularly notable in the case of cracksthat create a funnel effect through which channel heat and saltenlarging them.

In the presentation of the joint work, Schmidt, main author of the second study, sums it up as follows: “These new ways of observing the glacier allow us to understand that it is not just a question of knowing how much is melting, but how and where the melting takes place in these very hot parts of Antarctica.”

Conclusions from the possible collapse of Thwaites Glacier

The scientist concludes: “we see rifts, and probably terraces, through warming glaciers such as Thwaites. Warm water is seeping in through these fissures, helping to erode the glacier at its weakest points.”

References:

P. Davis and others. “Suppressed basal melt in the eastern Thwaites Glacier landfill zone“. Nature (2023).

B. Schmidt et al. “Heterogeneous melt near Thwaites Glacier grounding line”. Nature (2023)

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