Gaping hole in ozone layer 'is healing itself' scientists say

Montreal Protocol has prevented severe ozone depletion

Montreal Protocol has prevented severe ozone depletion

The reports, which are released every four years, note the improvement of Earth's protective ozone layer, which was in grave danger about 30 years ago.

"We're raising a flag to the global community to say, 'This is what's going on, and it is taking us away from timely recovery of the ozone layer, '" NOAA scientist Stephen Montzka, the study's lead author, said in a statement at the time.

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.

But the United Nations has today said it is finally healing, with the Northern Hemisphere's upper ozone layer expected to be repaired in the 2030s. Use of ozone-depleting chemicals has drastically decreased worldwide in the last 40 years, with chlorofluorocarbons (CFCs), the primary factor in the depletion of the ozone layer, phased out globally in the wake of the 1987 Montreal Protocol. The purple and blue colors are where there is the least ozone, and the yellows and reds are where there is more ozone.

"These new assessment results highlight the importance of continued long-term monitoring of HFCs in the atmosphere as the Kigali Amendment begins to take hold", said David Fahey, co-chair of the Montreal Protocol Scientific Assessment Panel and scientist at the NOAA Earth System Research Laboratory in the United States.

It is possible the healing of the ozone hole above Antarctica may insulate the continent and accelerate climate warming, but report co-author Ross Salawitch, an atmospheric scientist at the University of MI, said the immediate effects of ozone damage were such that it would be "incredibly irresponsible" not to protect the depleted ozone layer.

The Antarctic ozone hole is expected to gradually close, with springtime total column ozone returning to 1980 values in the 2060s.

Another problem is that new technology has found an increase in emissions of a banned CFC out of East Asia, the report noted.

"We are only at a point where recovery may have started", Toon said, pointing to some ozone measurements that haven't increased yet. Newman said we'll need to ensure that the replacements for these gases don't worsen global warming.

The ozone layer absorbs about 98% of harmful cancer-causing UV light - so it is vitally important.

"The Montreal protocol is one of the most successful multilateral agreements in history for a reason", said Erik Solheim, head of UN Environment.

'I don't think we can do a victory lap until 2060, ' he said.

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