The ozone layer that shields the earth from cancer-causing ultraviolet rays is showing early signs of thickening after years of depletion, a UN study says.
The report says it will take a decade before the hole starts to shrink.
Scientists say the recovery is entirely due to political determination to phase out the man-made CFC gases destroying ozone.
The study was published by researchers from the World Meteorological Organization (WMO) and the UN Environment Programme (UNEP).
“International action on the ozone layer is a major environmental success story… This should encourage us to display the same level of urgency and unity to tackle the even greater challenge of tackling climate change,” said WMO Secretary-General Michel Jarraud.
Dr Ken Jucks from the US space agency Nasa told BBC News that humans “have started to do the right thing in order to convert the atmosphere back towards what it was before the industrial revolution started”.
Scientists cannot be absolutely certain yet that the hole will heal itself. Prof David Vaughan from the British Antarctic Survey (BAS) said that test results from his organisation would throw extra light on the WMO’s findings.
“We have to be a bit cautious, but this does look on the face of it like some very good news,” he told BBC News. “Our own data from the Antarctic will take a few weeks to process but we hope to confirm the findings. If it’s accurate, it underlines the potential power of international agreement.”