Scientists investigate disappearance of lake in Antarctica – 01/28/2024 – Environment

Over the last few decades, a lake that once supplied an Argentine scientific station in Antarctica almost disappeared after a series of changes in its water level, being swallowed up by leaks that appeared in the region’s frozen soil.

Researchers from UFF (Universidade Federal Fluminense), together with colleagues from Argentina and other Brazilian institutions, are trying to understand how the lake’s disappearance could be linked to the consequences of climate change in the region, one of the most affected by global warming.

As far as scientists know, this is the first recorded disappearance of an Antarctic lake, although similar situations are occurring with some frequency in the Arctic.

“This is expected to be rarer in Antarctica simply due to the fact that these lakes are in the few ice-free regions of the continent”, explains Rosemary Vieira, professor at the UFF Institute of Geosciences who is a veteran of research in the region, having visited Antarctica 16 times since 2003. Today, less than 0.5% of the Antarctic surface corresponds to ice-free areas, in isolated stretches of the interior of the continent and along the coast.

This is the case in the region of the almost disappeared Lake Boeckella, which is located in Esperanza Bay, at the northern end of the Antarctic peninsula. The peninsula is the tongue of land that extends from the continent towards South America, and it is where Argentina’s Esperanza Antarctic Base is located, about 600 meters from the lake.

Until January 2001, the body of water had an average depth of more than six meters and was delimited by a type of natural dam whose dam was a moraine — a cluster of sediments dragged by glaciers in the past, which may include stones of different sizes , gravel and sand.

But there was also ice as “mortar” on the moraine. When it melted, the dam lost its ability to hold back the lake, which suffered a sudden decrease in its level. The team at the Argentine base tried to deal with the problem by building artificial dams, especially because the lake’s fresh water was important for its supply.

At the same time, however, everything indicates that the flow of meltwater from the Buenos Aires Glacier, nearby, increased to such an extent that it caused overflows in the lake between 2005 and 2007. The dams broke, causing damage including to the penguins in the neighborhood. “There are huge penguins there, and many animals were dragged away”, says Vieira.

Other processes were also taking place. Both on the lake bed and in the areas surrounding it there is permafrost (frozen soil from the polar regions).

“This soil is frozen for depths of tens of meters, but the upper part of it, normally a few meters thick and in contact with the air, is what we call the active layer. It can thaw and become frozen in new throughout the year. The problem is that this active layer became thicker”, reports the UFF researcher.

Holes then began to appear in the permafrost that Vieira’s Argentine colleagues call “agujeros”. Although the word derives from “aguja” (needle) in Spanish, the holes that continued to swallow the water were not thin at all, reaching meters in height and the width of a human being.

The process intensified in the 2010s, so that today what remains of the lake is just over 10% of the original volume.

“Our question is: is this associated with regional temperature? After all, we know that the Antarctic peninsula has already warmed by an average of around 4°C [em relação ao período pré-industrial]. We have data from a neighboring weather station in the region since the 1970s, as well as satellite data. Apparently, the change in temperature began to set in from the 1990s onwards, especially in the case of minimum temperatures, which became higher”, says the researcher.

It also remains to be seen whether the process will be repeated in other Antarctic lakes. Lake Buenos Aires, in the neighborhood, for example, has risen in level for now, but this appears to be due to the intense melting of the glacier of the same name.

“There are many variables, and of course this process must have impacts on the region’s environment because the lakes function as sources of water and food”, analyzes Vieira. Studies in the region continue this year, with a Brazilian team going there. “This time I had to be grounded and couldn’t board due to health problems”, she jokes.