ANT - 9.6 MILLION SQUARE MILES: Sizing up the Antarctic Ozone Hole Set to Persist Into November...
Persistent cold temperatures and strong circumpolar winds supported the formation of a large and deep Antarctic ozone hole that will persist into November, NOAA and NASA scientists reported today.
The ozone hole reached its peak size at about 9.6 million square miles (or 24.8 million square kilometers), roughly three times the area of the continental United States, on September 20. Observations revealed the nearly complete elimination of ozone in a four-mile-high column of the stratosphere over the South Pole.
This year will go down as having the 12th-largest ozone hole in 40 years of satellite records, with the 14th-lowest ozone readings in 33 years of balloon-borne instrumental measurements, the scientists said. Declining levels of ozone-depleting chemicals controlled by the Montreal Protocol prevented the hole from being as large as it would have been 20 years ago.
"We have a long way to go, but that improvement made a big difference this year,” said Paul A. Newman, chief scientist for Earth Sciences at NASA's Goddard Space Flight Center. “The hole would have been about a million square miles larger if there was still as much chlorine in the stratosphere as there was in 2000.”
What is ozone and why does it matter?
Ozone, composed of three oxygen atoms, is highly reactive with other chemicals. In the stratosphere, roughly 7 to 25 miles above Earth’s surface, the ozone layer acts like sunscreen, shielding the planet from ultraviolet radiation. Closer to Earth’s surface, ozone created by photochemical reactions between the sun and pollution from vehicle emissions and other sources can form harmful smog in the lower atmosphere.