The 2015 Antarctic ozone hole area was larger and formed later than in recent years, according to scientists from NASA and the National Oceanic and Atmospheric Administration (NOAA).
The ozone hole had expanded to its peak of 28.2 million square kilometres on 2 October, an area larger than the continent of North America.
Throughout October, the hole remained large and set many area daily records.
Unusually cold temperature and weak dynamics in the Antarctic stratosphere this year resulted in this larger ozone hole. In comparison, last year the ozone hole peaked at 24.1 million square kilometers (9.3 million square miles) on Sept. 11, 2014. Compared to the 1991-2014 period, the 2015 ozone hole average area was the fourth largest.
“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,” said Paul A. Newman, chief scientist for Earth Sciences at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
The ozone hole is a severe depletion of the ozone layer above Antarctica that was first detected in the 1980s. It forms and expands during the Southern Hemisphere spring (August and September) because of 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.
Bill Condie is a science journalist based in Adelaide, Australia.
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