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A United Nations report recognizing the role of the hole in the ozone layer over Antarctica is significant in understanding climate change in the Southern Hemisphere, a leading New Zealand government expert said Thursday.
The report, Scientific Assessment of Ozone Depletion 2014, is the work of a UN panel of 300 scientists and is due out in January, but a summary Assessment for Decision Makers, (ADM) was released Thursday.
Atmospheric scientist Olaf Morgenstern, of the government's National Institute of Water and Atmospheric Research (NIWA), who is a reviewer of the report and the ADM, said the report showed a broad consensus that considerable changes during summer since the late 1970s were mostly driven by ozone depletion.
"In other seasons, ozone depletion is a contributor, but other effects (increasing greenhouse gases) are thought to be more important," Morgenstern said in a statement.
The consequences included drying of parts of southern Australia, moistening of some subtropical regions and poleward shifts in the paths of low-pressure systems over the Southern Ocean.
One of the most important messages in the ADM was that the Montreal Protocol, an international treaty to phase out production of ozone-depleting substances, was working.
"It has stopped ozone depletion in Antarctica from getting worse. In the 1990s, this wasn't clear," said Morgenstern.
The ozone hole over Antarctica was expected to return to 1980 levels between 2050 and 2070, but that could be advanced by 11 years if the international community were to eliminate all future emissions of ozone-depleting substances, he said.
The ADM also highlighted that hydrogenated fluorocarbons used in air conditioning and refrigeration were potent greenhouse gases projected to increase substantially in coming decades, although they were not ozone-depleting.
The ozone and climate science communities were likely to become more closely aligned, with models used to inform future ozone assessment reports also increasingly used to inform climate assessments, he said.
The next Intergovernmental Panel on Climate Change report and the next Ozone Assessment would probably use the same model simulations as their basis of information.
