Scientists from the National Oceanic and Atmospheric Administration (NOAA) and NASA have said that this year, the Antarctic ozone hole area is larger and has formed later than previous years.
This is due to unusual cold temperatures and weak dynamics in the Antarctic stratosphere. Although in a bulletin from the World Meteorological Organization (WMO), it stressed that the temperature conditions in the stratosphere will vary from year to year, so that in some years the ozone hole is relatively small and in other years relatively large.
Watch as the Antarctic ozone hole nears record size, by SciNews:
Geir Braathen, a senior scientist in WMO’s Atmospheric and Environment Research Division, said in a statement: “This shows us that the ozone hole problem is still with us and we need to remain vigilant. But there is no reason for undue alarm.”
According to NASA, the ozone hole had expanded to a peak of 10.9 million square miles (28.2 million square kilometers) on Oct. 2 this year. The hole remained large and had set many daily records throughout October. Last year, the ozone hole peaked at 9.3 million square miles (24.1 million square kilometers) on Sept. 11, 2014. Compared to the 1991-2014 period, the 2015 ozone hole average area was the fourth largest.
Paul A. Newman, chief scientist for Earth Sciences at NASA’s Goddard Space Flight Center in Greenbelt, said: “While the current ozone hole is larger than in recent years, the area occupied by this year’s hole is consistent with our understanding of ozone depletion chemistry and consistent with colder than average weather conditions in Earth’s stratosphere, which help drive ozone depletion.”
The ozone layer above Antarctica is severely depleted and was first discovered in the 1980s. During August and September, the Southern Hemisphere spring, the Antarctic ozone hole forms and expands. It is due to the high levels of chemically active forms of chlorine and bromine in the stratosphere. These chlorine- and bromine-containing molecules are largely derived from man-made chemicals that steadily increased in Earth’s atmosphere up through the early 1990s, NASA wrote.
Bryan Johnson, a researcher at NOAA’s Earth System Research Laboratory in Boulder, said: “This year, our balloon-borne instruments measured nearly 100 percent ozone depletion in the layer above South Pole Station, Antarctica, that was 14 to 19 kilometers (9 to 12 miles) above Earth’s surface.
“During September, we typically see a rapid ozone decline, ending with about 95 percent depletion in that layer by October 1. This year, the depletion held on an extra two weeks resulting in nearly 100 percent depletion by October 15,” Johnson added.
Paul Krummel from CSIRO told ABC that there is a big difference when compared to last year, with it being the one of the smallest on record.
‘The past couple of years have actually been quite small ozone holes, but this year it is certainly quite large,
and for this time of year it is one of the largest or is the largest on record, but in terms of overall area compared to previous years, it’s about the third or fourth-largest,” Krummel said.
The ozone layer plays an important role in shielding Earth’s surface from potentially harmful ultraviolet radiation, which has been known to cause skin cancer, cataracts, and will also damage plants. With this year’s ozone hole being so large, it is likely to increase the ultraviolet rays at Earth’s surface in the coming months, especially in Antarctica and the Southern Hemisphere.
Newman told The New York Times: “The worry is the persistence of low ozone and the continued rising of the sun will contribute to a higher UV index” in the southern hemisphere. “If I lived down there, I would keep an eye on the UV forecast,” he said.
With the declining levels of the ozone-depleting chemicals chlorine and bromine in the atmosphere, the ozone hole is expected to recover back to 1980 levels by approximately 2070.