New report recognises climate change and ozone depletion links
The ozone hole over Antarctica is responsible for significant climate change in the Southern Hemisphere, according to a new international report.
The report, called Scientific Assessment of Ozone Depletion 2014, is due out in January, but a summary Assessment for Decision Makers, (ADM) has been released today.
The report, which is the work of a United Nations panel comprising 300 scientists worldwide, will assess the latest scientific evidence on ozone depletion and will be the first comprehensive update of its kind in four years.
NIWA atmospheric scientist Olaf Morgenstern, who is a reviewer of the report and the ADM, said the recognition of the role of ozone depletion in Southern Hemisphere climate change was significant.
“It means there is now a broad consensus that the considerable changes which occurred 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,” Dr Morgenstern said.
The consequences include 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.
Dr Morgenstern also said one of the most important messages in the ADM is that the Montreal Protocol – an international treaty to protect the ozone layer by phasing out production of ozone-depleting substances to which New Zealand, like all other UN member states, is a signatory - is working.
“It has stopped ozone depletion in Antarctica from getting worse. In the 1990s, this wasn’t clear.”
The ozone hole over Antarctica is expected to return to 1980 levels between 2050 and 2070. Dr Morgenstern said if the international community were to eliminate all future emissions of ozone-depleting substances, the return could be advanced by 11 years.
Meanwhile, the ADM also highlights that hydrogenated fluorocarbons used in air conditioning and refrigeration – used but not produced in New Zealand – remain a problem area. While not ozone-depleting, they are potent greenhouse gases projected to increase substantially in coming decades.
Dr Morgenstern said it was likely the ozone and climate science communities would become more closely aligned, with models used to inform future Ozone Assessment reports also increasingly used to inform Climate Assessments. The next Intergovernmental Panel on Climate Change report and the next Ozone Assessment will probably use the same model simulations as their basis of information.