Antarctica is quite a mysterious continent. It is located several thousand kilometers from Poland, and on some maps, due to surface distortions, it is completely omitted. Our country has two stations there – the year-round research station named after H. Arctowski (actually located in the Antarctic area, on King George Island in the South Shetland archipelago) and the polar station named after AB Dobrowolski, located in Antarctica, beyond the southern Arctic Circle (unused since 1979, there are plans to revive it).
The southern continent is 3 million square kilometers larger than Europe and is almost entirely covered by a layer of ice several kilometers thick. But it wasn’t always like that.
One of the main factors influencing the extent of the ice sheet is global temperatures. About 50 million years ago, the world was about 14 degrees Celsius warmer than it is today, with temperatures dropping for the next 16 million years. At that time, Antarctica did not resemble an icy desert, but rather a landscape known from Canada (taiga and tundra). At the Eocene-Oligocene boundary, 34 million years ago, the climate was about 8 degrees Celsius warmer than today.
Scientists point to two factors that caused the cooling. The first is carbon dioxide60 to 50 million years ago it was 2.5 to 5 times more than today. The decrease in this greenhouse gas allowed temperatures to cool all over the Earth, allowing ice sheets to form. And the changes in Antarctica itself were largely due to geology (specifically plate tectonics). The separation of North America and Antarctica opened the Drake Passage and allowed the formation of a cold circumpolar current known today as the Drift of the Western Windswhich makes it difficult for warm air masses to pass through the Southern Ocean.
There is also some evidence from oxygen isotopes in shells that are now part of the sediments on the ocean floor. They show a spike in oxygen-18 that occurred 34 million years ago, which may have been caused by the lighter isotope oxygen-16 hitting the Antarctic continent.
Since the Antarctic landscape was once different from today, there is nothing to stop the ice from melting completely again. Over the next millions of years, Antarctica will change its position and the climate will change many times, even if humanity is no longer around. What about current climate change? It is unlikely that climate change resulting from human activity will completely melt the ice sheet in the near future. However, even a reduction in its extent could have huge consequences for the environment.
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Source: geekweek.interia.pl
