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Very cold regions of Antarctica are more vulnerable to melting than previously thought, according to a new Dutch study. Since less snow falls in these places, meltwater lakes form more quickly on the ice in summer. These can break ice platforms. In the long term, this could lead to further sea level rise, with consequences for the Netherlands.
The largest ice cap in the world is located in Antarctica. It’s largely on land, but also extends into the adjacent ocean along the edges. These floating parts are called ice shelves.
Meltwater lakes form more rapidly in summer on colder ice shelves than on warmer edges of the ice sheet. This is clear from new research from Utrecht University and TU Delft, which was published in a specialist journal on Thursday. Natural climate change.
Wat is een ijsplaat en waarom zijn ze belangrijk?
- IJsplaten zijn drijvende plakken ijs langs de randen van Antarctica. Ze zijn honderden meters dik.
- De grootste ijsplaten bevinden zich in baaien, zoals de Amundsenzee, de Weddellzee en de Rosszee. Dat zijn grote inkepingen waar de oceaan diep landinwaarts reikt, richting de geografische zuidpool.
- Grotere ijsplaten zijn ook erg koud. Je zou er dus niet veel smelt verwachten. Maar omdat daar juist minder sneeuw valt, kan afsmelting er ‘s zomers sneller beginnen dan gedacht.
- Als de ijsplaten afbreken, stromen achterliggende gletsjers sneller naar zee. Dat versnelt de wereldwijde zeespiegelstijging.
- Voor Nederland is Oost-Antarctica het belangrijkst. IJsplaten in dat deel van de ijskap zijn misschien minder stabiel dan gedacht.
Indeed, the coldest ice shelves in Antarctica are much drier than other, warmer ice shelves. This means there is less snow on the ice. Snow acts like a sponge on meltwater, lead author Melchior van Wessem of Utrecht University tells NU.nl. With a thin layer of snow, meltwater forms lakes faster.
These lakes are darker than ice and therefore heat up quickly in the sun. This amplifies the warming. Meltwater can also flow into fractures, causing the pack ice to break up.
Fusion is slow, but getting faster
Where then is the tipping point for the melting of these cold, dry ice shelves? The Dutch researchers calculated this using a model. When the average annual temperature exceeds -15 degrees, the first meltwater lakes form on some ice shelves. It’s 10 degrees colder than other ice shelves where more snow falls.
This is not yet the case for the Rossplaat. According to the researchers, the tipping point could be reached later this century. West Antarctica’s smaller ice shelves will likely be gone by then. For example, sea level rise is a slow process that accelerates a little at a time.
As parts of West Antarctica The Ross Sea is also considered the Achilles’ heel of Antarctica. The sea forms a sort of wedge between the ice sheets of West Antarctica and East Antarctica. The latter contains much more ice and is much colder on average.
Rossplaat’s earlier disappearance is an old climate mystery
Geological research had already shown that the giant Ross Plate could collapse during warmer periods in the past. This was accompanied by a rise in sea level of several meters.
Given the cold climate of the Ross Plate, it was a mystery until now. Researcher Van Wessem cannot yet say whether new findings on the formation of meltwater lakes provide an explanation for this. “It’s certainly interesting for a follow-up study.”
East Antarctica is the most important for the Netherlands
The East Antarctic Ice Sheet also contains small indentations, such as the Amery Ice Shelf. And the conclusions of the Dutch researchers also apply to this, says Van Wessem. “Amery is a very cold ice shelf that is extremely dry. This shelf is so dry that many meltwater lakes are already there.”
“And there are other East Antarctic ice shelves where the threshold for meltwater lake formation appears to be low, or where it has already been reached,” explains the researcher.
Research is important for the Netherlands. This is because the loss of mass from the ice caps is not evenly distributed over the Earth. The loss of ice in Antarctica leads to greater sea level rise in the North Sea than the same amount of ice lost in Greenland.
Enlargement via complex gravity effects gets even stronger when it comes to ice loss on East-Antarctic. Exactly the parts that were previously considered stable, but where the new research also detects small weak points.
