The hole in the ozone layer is recovering gradually, but the pace is much slower than was estimated some years ago by the international scientific community. According to latest estimates, the thickness of the protective layer of the Earth from ultraviolet radiation levels will not recover to pre-80's, when detected broken until the period 2060-2075 . On day 16 marked the International Day for the Preservation of the Ozone Layer, sponsored by United Nations under the theme Universal participation : Ozone Protection unifies the world . This day commemorates the signing on the same date in 1987 the Montreal Protocol and was proclaimed by the General Assembly of the United Nations in 1994.
The hole in the ozone layer is not so, in reality, but a marked loss of thickness and protective ability of the mantle. Discovered around 1980 and identified the causative substances, chlorofluorocarbons (CFCs) and halons present in many pressure sprays of chemicals, the international community decided to take corrective action. Thus was born the Montreal Protocol in 1987 to accelerate the elimination of these substances and other compounds that cause ozone depletion.
Experts agree that the Montreal Protocol has achieved its objectives in good measure, are no longer issued CFCs and other ozone-depleting substances warming, but time spent by these compounds in the atmosphere is very long and the effects as delivered before 1987 will endure even decades.
State Meteorological Agency (AEMET) said that the recovery of ozone levels prior to the 80 will not be nearly complete by 2050, and even take longer in the Antarctic area, where it was not until 2060-2075. In the next twenty years will continue to form ozone holes of similar intensity to that of previous years.
austral spring
The process is repeated every year. With the arrival of the southern spring begins the destruction of ozone over Antarctica. During the winter in the stratosphere reach very low temperatures (below -78 ° C). These temperatures are needed to build the so-called polar stratospheric clouds. On its surface chemical reactions that destroy generate stratospheric ozone in the presence of sunlight and ozone depleting substances, acting as catalysts for the reactions.
why ozone destruction begins at the beginning of spring, as sunlight begins to influence again in polar latitudes.
The hole in the ozone layer reached its maximum extent on record in 2006, 29 million square kilometers, an area larger than North America, and 2008 was the fourth year in number and extent of ozone destroyed since 1999. This year, preliminary data show that ozone depletion has begun earlier than usual.
