Is the Antarctic “plug” really going to explode?

On May 13, 2021, a 4,320 km large glacier (Equivalent to the Spanish island of Mallorca)
Ronnie stage Ann
Antarctic.

Reasons for detachment from This glacier was named A76 The largest right now seems to be part of a natural cycle unrelated to global warming. Although interesting, the process, “
Calf calving Occurs incessantly: Ice fragments separate from Antarctic ice sheets, forming glaciers of various sizes, rarely as large as the A76.

But if they breed internally multiple times and at short intervals, this calf can mask the very worrying phenomenon associated with climate change that could determine the future of Antarctica, and also with sea level rise. Because Antarctica is completely a DomesticThat is, glacier expansion larger than Europe creates larger floating sites in the ocean.

The Antarctic polar cap and its main floors; Below, the cross section showing the height of the cap and the base (F. Rummy / Legos) © Cecil Acosta / Conversation

The latter is formed by the gravitational flow of ice from the continent to the sea and forms a protective barrier around Antarctica. In the same way that a cork holds a bottle of liquid, the bases hold ice on the mainland. Without this important role, enormous amounts would flow directly into the water, causing sea levels to rise.

Stage displacement

In recent years, scientists believe that climate change could weaken sites around Antarctica. As it warms, the oceans cause them to gradually melt and reduce their capacity. This is the main reason for the current mass loss in Antarctica.

Even more worrying is that global warming in 2002, as scientists have already noted, will cause complete displacement of sites in a very short period of time. Feedback site b, Located on the Antarctic Peninsula, decomposes in a few weeks, forming a significant acceleration of ice flow towards the sea in this region.

Destruction of the Larson B operating system in Antarctica, images from January 31 to April 13, 2002. We see the platform “intact”, but it is covered by melting lakes (very dark blue dots) and then it suddenly disappears. Where the platform was before, the ocean appears, and then it freezes, forming ice-covered sea ice (large light blue area) © NASA

In the summer, when the snow melts on the platforms, water escapes into the best holes of the snowfall. This melting water in some summers Too big to be absorbed by Snowback. Excess water then exits deeply, or accumulates on the surface and forms lakes.

This phenomenon, which is the result of the combined action of intrusion and the weight of the water, could break the ice vertically – we speak. ” Hydrofractionation “. The piece of the site (or in the case of Larson B at all) is thus disconnected from Antarctica and decomposes very quickly.

Says a theory that is still hotly debated in the scientific community today New glaciers The resulting build-up is very unstable and can collapse quickly, causing ice shelves to disintegrate quickly.

Siriguano Bay, South Shetland Islands (Antarctica) in November 2019 © Johann Ortones / AFP

Conversely, if the snowfall is sufficient to regenerate the holes in the ice, the melting water will freeze there and reduce the risk of cracking the platform.

30% of sites are threatened

This hydroforming occurs when the complex equilibrium between ice and liquid water – mainly produced by surface melting – occurs. This may happen in the future Global warming, Since the relatively obvious effect involves the improvement of surface melting.

However, climate change will also increase snowfall as temperatures are much lower in Antarctica. The (local) evolution of this equilibrium seems particularly uncertain.

With a colleague fromUniversity of Reading, We studied the evolution of this equation using a
Special climate model To mark the polar regions.

ெ A-76 »breaks out of an ice shelf in Iceberg, Antarctica – BBC report (Paul Morgan, Le 22 May 2021)

Our goal was to identify sites that could degrade to different rates of global warming. An increase of 4 C can lead to the disappearance of 30% of operating systemsPine Island. This glacier, completely disappearing,
Can make its own contribution to the 1.5 meter improvement From sea level.

If the greenhouse gas concentration continues to increase at the current rate, warming of 4 ° C will be reached before 2100. On the other hand, restricting it to 2 ° C – the minimum purpose of the Paris Agreements – is one half of reducing the risk of hydrofroxering.

Sea level rise and uncertainties

The decay of the ice shelves has not yet been taken into account in the reports IPCC. According to recent scientific studies, this process could lead to sea level rise of 1 to 2.8 cm by 2100, up to 9% compared to unaccounted forecasts.

The models used in these predictions may have underestimated the ice shelf, suggesting that these numbers are only a low estimate. Nevertheless, this phenomenon is very difficult to predict.

Some of them are in eastern Antarctica (Ameri for example) Are already subject to favorable conditions for decay, however they do not occur, and their particular geographical location may be due to the fact that they provide additional lateral support.

If there is one point to remember, it is the significant uncertainty associated with the risk of rapid sea level rise. Scientists now believe that the melting of Antarctica will mainly affect sea levelNorthern Hemisphere. So its local increase in Europe is directly dependent on the situation in Antarctica, which seems to be the determining factor in the future of our regions ையுடன் leaning towards the most catastrophic events at any given time with a situation.

This analysis was written by Christoph Kittel, a postdoctoral researcher in climate science at the University of Liege (Belgium).
The original article was published on the website Conversation.