The 2021 Antarctic ozone hole reached its maximum area on Oct. 7 and ranks 13th-largest since 1979, scientists from NASA and NOAA reported today. This year’s ozone hole developed similarly to last year's: A colder than usual Southern Hemisphere winter led to a deep and larger-than-average ozone hole that will likely persist into November or early December.
“This is a large ozone hole because of the colder than average 2021 stratospheric conditions, and without a Montreal Protocol, it would have been much larger,” said Paul Newman, chief scientist for Earth sciences at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
What we call the “ozone hole” is a thinning of the ozone layer in the stratosphere (an upper layer of Earth’s atmosphere) above Antarctica that begins every September. Chemically active forms of chlorine and bromine derived from human-produced compounds are released during reactions on high-altitude polar clouds. The reactive chlorine and bromine then initiate ozone-destroying reactions as the sun rises in the Antarctic at the end of winter.
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Image via NASA Goddard Space Flight Center