The healing signs of ozone layer was revealed on Monday by a new assessment report on Montreal Protocol (MP), the over 30-year-old global treaty which deals with reduction of ozone-depleting substances.
Recovery from the holes and thinning caused by aerosol chemicals has progressed at a rate of about 1% to 3% a decade since 2000, meaning the ozone layer over the northern hemisphere and mid-latitudes should heal completely by the 2030s, if current rates are sustained.
Scientists discovered the the ozone layer, particularly over the Antarctic region and as far up as Australia, had depleted in the 1970s.
The four-yearly review of the Montreal Protocol, a 1987 ban on man-made gases that damage the fragile high-altitude ozone layer, found long-term decreases in the atmospheric abundance of controlled ozone-depleting substances and the ongoing recovery of stratospheric ozone.
According to a United Nations report, the upper layer of ozone over the northern hemisphere will be repaired by 2030, and the damage over the southern hemisphere will be back to normal by the middle of the century.
The Montreal Protocol helped phase out ozone depleting chemicals, including chlorofluorocarbons - known as CFCs - which were used widely in the production of fridges and spray cans until it transpired that they contributed to the breakdown of the ozone layer.Читайте также: Trump points to second term as U.S. president
Paul Newman, chief Earth scientist at Nasa's Goddard Space Flight Center, described the discovery as "really good news". The worldwide agreement compelled the global community to begin the phasing out of ozone-depleting substances like chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and halons. The purple and blue colors are where there is the least ozone, and the yellows and reds are where there is more ozone. "Most potential is in increasing the energy efficiency of these appliances as 80% of the emissions are due to the use of electricity and 20% due to the release of the refrigerants", said Chandra Bhushan, deputy director general of the Centre for Science and Environment (CSE).
The amount of ozone in the stratosphere varies naturally throughout the year, with zone depletion most pronounced in polar regions, resulting in so-called ozone holes. The hole reaches its peak in September and October and disappears by late December until the next Southern Hemisphere spring.
If nothing had been done to stop the thinning, the world would have destroyed two-thirds of its ozone layer by 2065, Newman said.
Now scientists say the ozone layer is making a comeback and will make a full recovery in 42 years.
But the report, from the UN's environment and world meteorological organisation, said there is evidence of an unexpected increase in CFC-11 from eastern Asia since 2012.
"I don't think we can do a victory lap until 2060", Newman told AP.При любом использовании материалов сайта и дочерних проектов, гиперссылка на обязательна.
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