Arctic Ozone Layer Concerns Raised After Odd Arctic Ozone ‘Hole’ Found in 2011
October 8, 2015 Andrew Chernoff
It was this time last year that the United Nations released a report heralding the news that the the ozone hole that appears annually over Antarctica was showing it had stopped increasing and was showing signs of thickening.
The report published by the World Meteorological Organization (WMO) and the UN Environment Programme (UNEP), also indicated that it would take at least a decade before the hole over the Antarctic would start to shrink.
According to the report:
The phase-out of ozone depleting substances has had a positive spin-off for the global climate because many of these substances are also potent greenhouse gases. However, the assessment report cautions that the rapid increase in certain substitutes, which are themselves also potent greenhouse gases, has the potential to undermine these gains. The assessment also notes that there are possible approaches to avoiding the harmful climate effects of these substitutes.
“There are positive indications that the ozone layer is on track to recovery towards the middle of the century. The Montreal Protocol – one of the world’s most successful environmental treaties – has protected the stratospheric ozone layer and avoided enhanced UV radiation reaching the earth’s surface,” said UN Under-Secretary-General and UNEP Executive Director Achim Steiner.
“However, the challenges that we face are still huge. The success of the Montreal Protocol should encourage further action not only on the protection and recovery of the ozone layer but also on climate. On September 23, the UN Secretary General will host Heads of State in New York in an effort to catalyse global action on climate. The Montreal Protocol community, with its tangible achievements, is in a position to provide strong evidence that global cooperation and concerted action are the key ingredients to secure the protection of our global commons,” he added.
“International action on the ozone layer is a major environmental success story,” said WMO Secretary-General Michel Jarraud. “This should encourage us to display the same level of urgency and unity to tackle the even greater challenge of climate change. This latest assessment provides solid science to policy-makers about the intricate relationship between ozone and climate and the need for mutually-supportive measures to protect life on earth for future generations.”
“Human activities will continue to change the composition of the atmosphere. WMO’s Global Atmosphere Watch programme will therefore continue its crucial monitoring, research and assessment activities to provide scientific data needed to understand and ultimately predict environmental changes, as it has done for the past 25 years” said Mr Jarraud.
Early this year, Australian news reported that scientists discovered previously neglected class of ozone-depleting gases increasing and having an effect on the ozone layer. The study, published in the journal Nature Geoscience, looked at two decades of raw data provided by the US National Oceanic and Atmospheric Administration (NOAA).
According to the news article:
Researchers at Leeds University in northern England said two computer models highlighted the impact of so-called ‘very short-lived substances’ (VSLS) that deplete the stratospheric shield.
The damage they do to the ozone layer is significant and likely to increase, they said, as emissions of man-made chlorine gases rise.
Ironically, one of the chemicals named in the report, dichloromethane, is used in the manufacture of substitutes for ozone-depleting gases outlawed by the UN’s 1987 Montreal Protocol.
VSLS are gases that usually break down in less than six months. They are not covered by the landmark Montreal Protocol that requires the phaseout of longer-lasting chlorofluorocarbon (CFCs) and halon gases.
“Our model simulations indicate that VSLS account for a significant portion of ozone loss in the stratosphere,” lead investigator Ryan Hossaini said.
“In the Antarctic region, where the ozone hole forms each year and where ozone decreases are the most dramatic, we estimate that VSLS account for about 12.5 per cent of the total ozone loss.
“Globally averaged, the ozone loss due to VSLS in the lower stratosphere could be as much as 25 per cent, though it is much smaller at higher altitude.”
Around 90 per cent of VSLS are natural — they are bromine compounds produced by seaweed and the ocean’s phytoplankton.
The rest is man-made chlorine gases, and their contribution to the VSLS total is rising fast.
“Dichloromethane appears to be one of the most abundant man-made VSLS that we know of,” said Hossaini.
Compared with the notorious CFCs, dichloromethane’s impact today is small. The computer models suggest it reduces the ozone layer by less than one per cent, he said.
“However, our study also shows that the atmospheric concentration of dichloromethane has increased dramatically in recent years,” said Hossaini.
“At some locations its atmospheric concentration has doubled since the late 1990s.”
ARCTIC OZONE LAYER
In 2011, according to a NASA study, cold temperatures, chlorine and a stagnant atmosphere caused a thinning in the ozone layer over the Arctic in 2011.
According to the study conclusion:
Even when both poles of the planet undergo ozone losses during the winter, the Arctic’s ozone depletion tends to be milder and shorter-lived than the Antarctic’s. This is because the three key ingredients needed for ozone-destroying chemical reactions -chlorine from man-made chlorofluorocarbons (CFCs), frigid temperatures and sunlight- are not usually present in the Arctic at the same time: the northernmost latitudes are generally not cold enough when the sun reappears in the sky in early spring. Still, in 2011, ozone concentrations in the Arctic atmosphere were about 20 percent lower than its late winter average.
The new study shows that, while chlorine in the Arctic stratosphere was the ultimate culprit of the severe ozone loss of winter of 2011, unusually cold and persistent temperatures also spurred ozone destruction. Furthermore, uncommon atmospheric conditions blocked wind-driven transport of ozone from the tropics, halting the seasonal ozone resupply until April.
“You can safely say that 2011 was very atypical: In over 30 years of satellite records, we hadn’t seen any time where it was this cold for this long,” said Susan E. Strahan, an atmospheric scientist at NASA Goddard Space Flight Center in Greenbelt, Md., and main author of the new paper, which was recently published in the Journal of Geophysical Research-Atmospheres.
“Arctic ozone levels were possibly the lowest ever recorded, but they were still significantly higher than the Antarctic’s,” Strahan said. ” There was about half as much ozone loss as in the Antarctic and the ozone levels remained well above 220 Dobson units, which is the threshold for calling the ozone loss a ‘hole’ in the Antarctic – so the Arctic ozone loss of 2011 didn’t constitute an ozone hole.”
According to livescience.com, on its coverage of the study:
Strahan and her team calculate that two-thirds of the thinning was caused by a combination of chlorine pollution and extreme cold. The remaining third was caused by the oddly quiet atmosphere, which prevented ozone molecules from elsewhere from moving in to fill the gap.
The ozone layer over the Arctic returned to normal in April 2011. It’s unlikely that such thinning will become a reoccurring problem, because the meteorological conditions were so odd, Strahan said. Not only that, but CFC levels in the atmosphere are still declining.
“If 30 years from now we had the same meteorological conditions again, there would actually be less chlorine in the atmosphere, so the ozone depletion probably wouldn’t be as severe,” she said.
Ongoing scrutiny continues on the Arctic and its ozone layer, as the following video indicates:
What does all this mean?
While we are doing more to lessen the impact of human pollution on earth, more still needs to be done. In saying that though, odd weather happenings and other climate issues out of our immediate, short term control, still impact our ability to continue and advance the timetable that we set for ourselves to solve the many issues affecting our environment……Just saying….
INFORMATION ON THE OZONE LAYER: