Antarctica (Antarctica) refers to the region including the Antarctic point on the earth, or the Antarctic continent centered on the Antarctic point and the islands and sea areas (Antarctic Ocean) around it. The area centered on the Antarctic point up to 66 degrees 33 minutes south latitude is called the Antarctic Circle. There is an Antarctic Convergence Line, which is a discontinuous line of ice blocks that draws an irregular shape from latitude 50 to 60 degrees south, and the area south of this is also called the Antarctic region. The Antarctic region includes the Antarctic Ocean centered on Antarctica, and also includes parts of the Pacific Ocean, Indian Ocean, and Atlantic Ocean.
The Antarctic Treaty, which came into effect in June 1961, has frozen the claim of sovereignty south of latitude 60 degrees south (as of 2021, some countries still claim sovereignty) for military use. , Nuclear tests are also prohibited.
It consists of Antarctica and the Southern Ocean. Antarctica is one of the coldest regions on the planet, covered with ice sheets (ice sheets) that have accumulated for about 30 million years and have not melted, forming a thick ice layer of 1000 to 2000 meters. There is almost no vegetation, except for lichens in the coastal areas of the area. Most of the land is under the ice floor, and there are few open rock areas. The ice sheet becomes a glacier and slowly slides down the slopes of the mountains and is pushed out into the sea, forming ice shelves in some areas. Ice shelves are pushed offshore, cracked by their own weight and drifting in the sea as icebergs.
Antarctica consists of West Antarctica in the Western Hemisphere and East Antarctica in the Eastern Hemisphere, with East Antarctica having a larger area. West Antarctica has the Antarctic Peninsula, and the northern end of this peninsula is near 63 ° S and outside the Antarctic region. Since it is a tundra climate zone and it is warm in Antarctica, observation bases are also concentrated.
Antarctica and environmental issues
Antarctica, which is a polar region at high latitudes, is more affected by global warming than low- and mid-latitude regions such as Japan. Observations at the bases in the Antarctic Peninsula show that global warming is clear both annually and seasonally, with the temperature rising to 2.5 to 3 ° C in 50 years at the Faraday base. However, on the other hand, neither warming nor cooling is seen in other regions, especially in the "East Antarctica" of the continent itself. There are no major changes at Syowa Station or the record of temperature changes over 50 years. In addition, cooling (a decrease of -0.17 ° C in 10 years) is rather observed at the inland Antarctic base. On the East Antarctica coast, the spread of sea ice has not decreased, and conversely, it is consistent with the report that the area has increased. Thus, global warming is not clear on the ground in the main body of Antarctica. In this way, at present, there are no noticeable signs of global warming in temperatures and ice sheets outside the peninsula, but depending on the atmospheric flow over the Southern Ocean, there is a possibility that it will tend to warm. Need to be careful. While there is no tendency to warm on the ground, the sky is warming. The temperature rise is clear in all layers of the troposphere, especially at 600hPa altitude (about 4000m altitude) in the middle layer, which has risen by 0.7 ° C in 10 years. It can be said that all layers of the troposphere are warming. However, in the upper stratosphere, the temperature has dropped and it has become cold. In the stratosphere, the balance is maintained mainly by heating by absorbing ultraviolet rays by ozone and cooling by radiating infrared rays by greenhouse gases such as carbon dioxide. When carbon dioxide increases, the infrared cooling effect becomes stronger and it becomes colder, and ozone decreases. If this is done, the heating with ultraviolet rays will be reduced, so that it will be cooled. At present, the ozone hole has not recovered and carbon dioxide is increasing, so it is thought that the stratosphere is cooling. Also, the ozone hole is located in Antarctica.