The continent is far from stable and constant glacial ring somewhere around the South Pole. As pointed out by Dutch researchers from Utrecht, is the fifth largest continent much more vulnerable than we previously thought. And we with him. If all the ice in Antarctica melted, sea levels would rise by 55 meters.
As informs journal Science Alert , current research, a team of Dutch geophysicists brings a fundamental change of view on Antarctica. Their expedition to "crater" in the east of the continent, in the locality bearing the name of the Belgian King Baudoin, had confirmed that that depression is not at all a crater, but "lake". Each of the two quotes are in place, the reason that we are moving in the landscape of eternal ice. The presence of two kilometers wide terrain depression with significantly darker ice served since 1989 occasional reports pilots who over flew above the given area. For years it was speculated that this is a depression crater left by the meteor trail.
This popular theory, however, has been increasingly questioned. They disagreed with her, nor the people of Utrecht University in the team Stef Lhermitta, who decided to explore this natural phenomenon on the spot. Why is not done so long ago? In defense of the proponents of possible theories about the origin of terrain depressions it should be noted that the site is located 400 kilometers from the nearest polar stations and the path to it, which is possible only for a few weeks a year, involves a three-day trip on snowmobiles. So when Stef Lhermitte achieved his goal and saw about three meters below the ground surface plunge, could only say: "I certainly do not look here for a meteorite crater, but something even more serious. The darker surface is covered by ice sunken lake. "
What is the problem? The lake is direct evidence of significant warming in the region, which we have not yet considered permanently frozen. On the site also noted the presence of three glacial cracks called. Glacial mills, which can be imagined as a vertical gully rotten melting ice water in which it waged two directions under the ice. A similar view was not experienced foreign polárníkům working ice, ice caves, frozen canals and lakes familiar example of Greenland. But Antarctica was always considered too cool and compact it so that similar phenomena occurred. Lhermitte with colleagues explored the site and made a series of records to refute the possible doubts. But Nata indicated runoff water and glacial mills did not make them too much space.
The location is certainly a question how he can in the frigid wastes of Antarctica to melt anything? The answer is quite simple and is based on natural physical processes affected today most likely climate warming. Over Antarctica had a bath so. Katabatic winds (from the center to the coast). Their action may not seem critical, achieving strength of only about 35 km / h. But they are the hot and dry conditions and therefore convenient locations disrupt the icy surface. The melting glaciers alone would not be sufficient, but that vyvanou surface layer of snow on the "bare" ice creates several-eye shadows. The darker place then attract more sunlight than significantly reflecting surface snowy ice. And then there's the real point.
And then it's just myself appreciating feedback. The layer is natátého ice-water, the stronger is darker and more attracts the sun's rays. Water on the surface of the glacier is working, disrupting its structure and eroding the original crust. A recessed created lake, which can viewed from above remind "crater". "The pressure of the water on the glacier ground was so pronounced that there was proboření or ingress of water below the surface. What we see is a remnant of surface or subsurface melted water from the lake, "explains Jan Lenaerts, a member of the research team.
This mechanism, distorting the structure of glaciers, usually stops the action of other natural conditions. The frozen lake surface in glaciers lost in a blizzard zasněží, it becomes white and cease to melt. The process is simply stabilizes and returns to its original state. But it is in Antarctica, where researchers would not particularly expect, what happened this time. The volume of ice in Antarctica is approximately 25.4 million km3 and until now was considered "securely bonded." With significant decomposition, melting or breaking off increased peripheral ker here in coming decades even if the current trend of global climate change foreseen. Research Lhermitta brings to this quiet forecasts a considerable element of uncertainty.
"The ice of Antarctica are tied tens of meters high levels of seas and oceans," says Lenaerts. "And our research shows that the whole region of East Antarctica is to climate change is far from immune."
All research and its description is processed in a very impressive web presentation .
Author: Radomír Dohnal
Source: Ekolist.cz
