Saturday, October 26, 2013

Antarctic ozone hole smaller than the average for the last 20 years - Spiegel Online

Washington – The ozone hole over Antarctica has shrunk. In September and October, there was an average of 21 million square kilometers, said the U.S. space agency NASA on the night of Saturday with Washington. So it was this year, significantly less than the average for the past two decades.

Since the mid-nineties, measured on the basis of NASA satellite data size of the ozone hole in the average of the two months lie at 22.5 million square kilometers. However, the data of one year were not sufficient to say whether the hole will lower the long term, said the Nasa.

was the biggest hole that changes daily in its dimensions, this year on 16 September, 24 million square kilometers, about the size of North America. The largest ozone hole ever recorded on 9 September 2000 but was still nearly six million square kilometers greater.

unfiltered UV light penetrates to the earth

The ozone layer surrounds the earth as a shield. Since the early eighties, scientists observed a decrease of ozone in the stratosphere (15 to 50 km altitude). Over Antarctica they reported first time in 1985 after an ozone hole that forms in the south polar winter. Due to the thinner ozone layer penetrates more unfiltered UV light on the earth, which can cause skin damage including skin cancer and eye. Many countries have committed themselves to the Montreal Protocol of 1987 to protect the ozone layer and the production of ozone-depleting chemicals, mainly from CFCs stopped.

In recent years, there have been reports about the fact that the ozone hole could close again. “If the trend continues, then closes after these model calculations, the ozone hole, and the ozone layer will regenerate,” scientists predict about the German Centre for Aerospace. However, experts are divided on how climate change will affect the CFC processes in the ozone layer.

CFCs are very stable and slowly build up in the atmosphere. The chlorine atoms present can destroy the ozone layer for decades. In Germany, CFCs are no longer produced since 1994. Without a global ban on CFCs, the ozone layer in 2050 would be almost completely destroyed world, says Markus Rex from the Alfred Wegener Institute for Polar and Marine Research. Even in our part of it would have been in this case a huge problem with the UV radiation.


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