Climate change is a fact, it is here to stay and with it all the consequences that it brings. The ecosystems most affected by these constant increases in temperatures have been the large frozen water reserves, the most transcendental and of great scientific interest is Antarctica; White continent covered in 98% ice, with a thickness that exceeds 4000 meters in some places.
A group of scientists led by Pedro Llanillo and Raúl Cordero from the @AntarcticaCL research group belonging to the University of Santiago, managed to detect the primary mechanism that is affecting Antarctica, in the same way in the Chilean Antarctic Territory.
They noticed the intrusion of warm waters, after measurements carried out in the summers of 2016 and 2017 in Fildes Bay (King George Island). These waters coming from the Antarctic Circumpolar Current, a cold marine current that flows freely from west to east around Antarctica, follow the same direction of the Earth’s rotational movement. This occurs because this current does not find any continent in its entire trajectory that interferes with its circulation.
The rise to the surface of warm waters is the main mechanism that explains the melting of coastal glaciers, floating ice shelves in West Antarctica and the Antarctic Peninsula, although it has also been reported in other parts of West Antarctica, it had not been detected the entry of this current to the investigated area. Until now.
According to Cordero, «this type of intrusion of warm water into the bay has been increasing throughout West Antarctica«, this fact has consequences. However, some branches of the current separate and flow south, mixing with the coastal waters of Antarctica that are colder, less saline and better oxygenated.
The research works showed that there is an entry and combination of warm waters in the subsurface of the bay under study. The warm waters detected come from the Antarctic Circumpolar Current (ACC), which was explained above. On the other hand, there are diversions of the current, which divide and circulate in a southerly direction where they mix with the coastal waters of Antarctica, these have a lower temperature and show a decrease in salinity, although they have a greater presence of oxygen.
Related to this behavior of the waters the expert Pedro Lanillo explains the following, «The intrusion of warm waters in subsurface is a phenomenon that is happening in several coastal regions of Antarctica, this contributes to accelerate the disintegration of the floating ice shelves and to the retreat of the Antarctic tidal glaciers «. Therefore, what has happened in the last time would explain that the accelerated melting of the white continent leads to an increase in the winds around Antarctica, this brings with it warm waters to emerge towards the surface, melting the ice present in the ocean and coasts. This phenomenon causes surface ice to melt in fractions of days, including large floating ice.
These warm waters can alter the stability of the glaciers present in Fildes Bay, for example, causing a rise in sea level, where the most affected territories would be the tropics, experts emphasize. Also some coastal areas of our country.
Antarctic ice sheet simulator model
The information was extrapolated into a mathematical model designed by glaciologist Frank Pattyn, from the Free French University of Bruxelles, in conjunction with the University of Chicago. This model called » GRANTISM Ice Sheet Dynamics » is based on mathematical calculations that manage to simulate changes in the volume of ice in a timeline. The mathematical model is based on the physical characteristics and deformation of the ice, which are expressed in formulas and the use of mathematical principles are translated into computer code.
Antarctic ice sheet
- For a colder climate, our model ice sheet grows larger, while the rate of accumulation inside the ice sheet is lower than it is today. The latter is explained by the fact that very cold air is also very dry and cannot contain much moisture. Ice speeds are much lower than currently modeled. This shows that the viscosity of the ice changed: the ice became stiffer, causing the ice sheet to grow a bit more. The ice sheet also expands laterally, due to the presence of ice sheets in the northern hemisphere that cause the sea level to drop significantly.
- In warmer climate conditions (+5, +10 ° C), the ice sheet seems to grow as well, even though melting occurs at the edges and the ice sheet flows faster, due to the higher viscosity with warmer temperatures. However, accumulation in the vast interior of the ice sheet has increased, as warmer air can hold more moisture, resulting in more precipitation. Significant melting occurs at the edge of the model ice sheet.
- Only at higher background temperatures (+15, +20 ° C) does the ice sheet begin to shrink in size, because melting becomes decisive. Not only are the summer temperatures above the melting point, but the annual mean temperature reaches positive values, which implies a positive temperature throughout the year and, therefore, ablation (the set of processes such as sublimation , melting and evaporation reducing snow or ice from the surface of a glacier or snow field).
The attached graph shows a simulation linear flow in the behavior of Antarctica, with respect to its ice sheets in steady state, linked to current climatic conditions (TFOR = 0). Upper left panel: ice sheet geometry (observed and modeled); upper right panel: superficial and basal velocity (m / a); lower left panel: surface mass balance, accumulation and ablation (m / a); lower right panel: mean annual temperature and mean surface temperature in summer (° C).
In conclusion and extrapolating the information obtained from the study by the scientists of the University of Santiago and the mathematical model of Pattyn, they agree that the sustained increase in temperature will be the determinant that will continue to deteriorate all the ecosystems that for millions of years were frozen, the it will probably disappear forever, the point of no return seems to be getting closer and closer, and the most tangible way to appreciate it is in the melting of Antarctic ice and glaciers of all kinds. The summary of everything exposed in this article is called climate change.
To see: the dynamics of the Antarctic ice sheets, their behavior, temperature, speed and mass balance, as the years go by according to the described mathematical model, they can be accessed for free at the link. It is also possible to simulate the ice sheet in Greenland where the situation is less hopeful.
CIGA-FGC Agreement: This article was published under the collaboration agreement between the GAIA Antarctic Research Center of the University of Magallanes and the Fundación Glaciares Chilenos.
- Diario La Tercera :» La Antártica se derrite» Link
- Modelo Matemático, »GRANTISM» diseñado por el glaciólogo Frank Pattyn Link
- Imágenes referenciales de la Antártica: todas pertenecientes a Alfredo Soto Ortega.
- Ubicación Bahía Fildes, zona del estudio Link
- Gráfico: Modelo de derretimiento de casquetes de hielo, Universidad de Chicago Link