What is the global environmental change that Antarctica was supposed to be covered by ice? And what is the balance of the global environment that you can see from there

ByRonald Woan

It was isolated from other worlds in an extremely cold placeAntarcticaIs an area with an unparalleled environment even on the Earth where 98% of the surface area is covered with ice. There were various opinions about when and how how Antarctica was completed and became the earth closed by ice, but the newly published research results showed that a combination of several theories is a powerful The way of thinking has been advocated and from that there is a way of seeing how delicate the balance of the climate change of the earth is made.

Scientists explain how Antarctica was formed - Business Insider
http://www.businessinsider.com/how-antarctica-formed-2017-2

Once in the continent with other continentsGondwanaThe Antarctica, which had formed a part of it, decided to follow a different fate from other continents after separating and moving. Antarctica, the fifth largest in the Earth and approximately twice the size of the continent of Australia, is predominantly covered by ice with a thickness of 1.6 km, with 90% of the Earth's ice reaching the South Pole Concentrated on the continent, 70% of freshwater is present. Due to the environment closed by ice, it is not suitable for the inhabitation of most animals including humans, and plants which grow naturally are very few, making it an extremely harsh environment for creatures.

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It is thought that 34 million years ago it began to make ice sheets in such Antarctica. As the sudden change of the environment occurs, the temperature of Antarctica drops greatly and it will be transformed into the earth closed by ice, but the cause is "changes in the global environment" and " Changes in the ocean current "were two theories were cast. However, it seems that any of them was missing in the decision strike. Meanwhile, the research team at McGill University's Department of Earth and Planetary Sciences pointed out the decisive cause of causing ice sheet formation in Antarctica by combining these two theories.

Going back to the history of the earth When Antarctica was still part of Gondwana still during the period from the Paleozoic to Mesozoic period of 500 million years ago to 65 million years ago, Antarctica is located north of the present It was. It is thought that Antarctica of that time was not an extremely cold and dry land like now, but a climate belonging to the temperate zone and tropical zone existed. Therefore, it is thought that many animals lived on the continent, plants grew thick. Also, the Earth at that time is in the state of "global warming" now, the climate is milder than it is now, and ice covering Antarctica did not exist.

It was about 40 million years ago when the change came to Antarctica. Gondwana gradually starts to separate, Antarctica starts to move south away from the supercontinent. However, even at this time, no ice sheet like the present was formed in Antarctica. Because the climate was mild and the environment surrounding the Antarctica was quite different from the present, it is because the environment covered by ice was located close to Antarctica.

The major change in the environment is that Antarctica is separated from the tip of the South American Continent - Horn Cape nowDrake StraitsIt was about time when it was formed. When the two continents were connected, the South Pacific and the South Atlantic as it is today were divided, but with the birth of the Drake Strait, the current in this area will change dramatically. A large amount of seawater starts to flow in the strait born between Antarctica and the continent of South America and eventually flows from the west to the east as surrounding the Antarctic continentAntarctic reflux"Is now being formed.

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As the Antarctic circulation flows around the Antarctic continent, the warmer currents from the Pacific and the Atlantic will soon not flow into this area and the temperature in the area begins to decline. Just since around this time, snow accumulated in Antarctica, and eventually ice sheets began to be constructed. This is considered to be one reason why so many ice has accumulated in Antarctica. However, it was thought that this alone would not cause enough change to develop the situation of Antarctica as it is now.

Therefore, what the research team brought out is that the global environment has changed significantly due to changes in the ocean current. It is a new theory that the research team is advocating that the environment of the earth has turned to cooling by the change in the circulation of the heat of the whole earth due to the newly born ocean current.

As a result of the Antarctic reflux being born as described above, the warm ocean current which had been flowing so far loses its position and a flow toward the north again occurs. With this flow, the warm ocean current which had been carried to the vicinity of Antarctica was pushed back, and heat accumulated in the area close to the equator. The heated seawater evaporates, forming clouds above the sky and rain. The change in the environment of the earth will come in the form of warm ocean current returned by the occurrence of Antarctic reflux, further warming of seawater and rainfall will increase, just "When the wind blows, the barbarians make profit".

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Further chain reaction will continue. As precipitation increases, more plants growing on the surface will grow. Plants absorbed carbon dioxide one after another and became to generate more oxygen by photosynthesis, the concentration of carbon dioxide on Earth started to decrease continuously. Also, even if carbon dioxide is absorbed in one of the minerals constituting the earth · silicate, the CO 2 concentration of the Earth will continue to decline.

As is well known, carbon dioxide is a greenhouse gas, so its concentration decreases and the atmosphere of the earth weakens its ability to retain heat. As a result, the average temperature of the Earth gradually declined. Just as the opposite world "global warming" which is regarded as a problem in the present society occurs "global cooling", the ice sheet of Antarctica has grown more steadily as a result of research It is a new logic that the team announced.

ByEli Duke

Dr. Gallen Herverson of McGill University, co-author of the paperRelease statement"In the context of climate change, this is an important lesson.This paper presents two different climate conditions, the era with no glaciers that occurred in Antarctica, the era with glaciers, It shows how the climate change is a complex mechanism and from the geological time flow that the change of the ocean current is the change of the planet It means that it has a big influence on the whole climate, "he says about the significance of research content.

From this study, we can see how the earth's climate is built up on a complex balance, and it works on a very large scale. Also, in light of the sharp pace of global climate change, which has been regarded as remarkable in recent years, it seems that the meaning weight further increases.

Papers by the research team can be referred to from the following links.

Enhanced weathering and CO2 drawdown caused by latest Eocene strengthening of the Atlantic meridional overturning circulation: Nature Geoscience: Nature Research