The ozone layer, located 10-50 kilometers above Earth’s atmosphere, is a protective layer of the Earth, it can effectively block ultraviolet radiation from the sun, the Earth’s biological, including humans to protect. The ozone layer is not evenly distributed on the earth’s surface, and the ozone layer in the three polar regions of the world, namely the Antarctic, Arctic and Qinghai-Tibet Plateau, is significantly thin. If the ozone level in the ozone layer somewhere were reduced to less than 50% of its normal level, scientists would say it was an ozone hole.
Our reporter Zhang Qi, correspondent Yan Changkun
Ozone levels over much of the central Arctic, about three times the size of Greenland, are now at record lows and will go down in history as an extraordinary atmospheric phenomenon, according to Nature.
Why does the Antarctic ozone hole appear every year, but the Arctic rarely appears? What is the cause of the ozone hole in the Arctic this time and what impact will it have? With these questions, the reporter interviewed Yang Yang, a professor at Nanjing University of Information Engineering’s School of Environmental Science and Engineering.
Hollows are triggered by low temperatures and polar vortex
Yang Yang pointed out that the Antarctic ozone hole is a very important reason, is because in winter, the Antarctic over there will be a deep polar vortex, so-called polar vortex, refers to the air in the sinking process encountered mountains or other terrain blocked, will stop the circulation and change to local rotation, inhaling cold air to form a strong vortex around the polar rotation. The air flow rotates clockwise along the Antarctic Plateau, sealing the Antarctic continent into a natural “net cover” that prevents air containing high levels of ozone from entering the Antarctic from the outside. The polar vortex in Antarctica is stronger and lasts longer than the North Pole due to atmospheric fluctuations.
There is another reason why Antarctica is more prone to the ozone hole than the Arctic – Antarctica usually has a lower temperature than the Arctic, where polar stratospheric clouds containing ice crystals form when temperatures below -80 degrees C, and chlorides break down as carriers of polar stratospheric clouds to release chlorine; But with the arrival of the end of the Antarctic spring, the polar vortex will gradually become incomplete or disappear, ozone-rich mid-latitude air is replenished to the South Pole, the ozone hole will quickly disappear.
“But this is rare in the Arctic, where temperatures are not as low as antarctic aseaching, and polar stratospheric clouds are not easy to form, which usually does not lead to large-scale ozone depletion.” Yang Yang said that the Arctic region in addition to 2011 experienced ozone depletion, in recent years is relatively normal, but this year there is a strong cold air, coupled with strong west wind around, cold air trapped in the polar vortex, only induced similar to the Antarctic ozone hole events.
In late March, measurements of weather balloons released by the Arctic Observatory showed that ozone levels had been reduced by nearly 90 percent at an altitude of 18 kilometers above the Arctic surface. Markus Rex, an atmospheric scientist at the Alfred Wegner Institute for Polar and Oceanic Research in Germany, said the normal measurements of weather balloons there were typically about 3.5 ppm (millionths), compared with about 0.3 ppm this time. The ozone hole over the Arctic is probably the largest on record in the Arctic, and is about the size of the one that forms in the Antarctic each year.
or will self-recover ingres stos without threatening human health
Scientific studies have shown that for every 1% reduction in ozone in the atmosphere, the amount of ultraviolet light that hits the ground increases by 2%, and humans face the threat of skin cancer, cataracts, immune system defects and stagnant development. At the same time, increased ultraviolet radiation can cause crops to yield a lot of production, even killing some fish and marine life. When scientists first discovered the hole in the ozone layer over Antarctica, humans thought that life on Earth could be destroyed as a result.
In the 1980s, scientists found that, in addition to natural factors, chlorine-containing compounds produced by human activities were also a major cause of the emergence of the Antarctic ozone hole. To that end, in September 1987, under the auspices of the United Nations Environment Programme, countries signed the Montreal Protocol on ozone-depleting substances, which agreed on the need to reduce the production and consumption of HCFCs in stages and minimize the damage to the ozone layer caused by human social activities. With the joint efforts of human beings all over the world, the Antarctic ozone hole has been gradually shrinking in recent years.
So will the Arctic ozone hole affect the Earth’s ecology?
“It’s not going to have much impact on the natural world yet. Yang yang said the probability of the hole then shifting to lower latitudes is very small, and even if there is a shift, people can also apply sunscreen to achieve protection. Normally, as the sun slowly rises and the polar vortex breaks, the ozone layer can soon return to its usual state. The hole in the ozone layer is likely to recover naturally in the coming weeks without threatening human health, the journal Nature notes.
While the Arctic ozone hole is a cause for concern, scientists believe it is a rare natural phenomenon, not an ecological crisis on earth.