Ozone: Sky not falling
Arctic levels reach new low, but there's a lot of ozone over us."
Arctic ozone depletion "has reached an unprecedented level," the World Meteoorlogical Organization reported this morning.
And while that certainly has rung some alarm bells and appears to track with what would be expected with worldwide warming, civilization need not panic just yet, according to ozone expert Bryan Johnson.
"There's a lot of ozone over us," said Johnson, a research chemist with the National Oceanic and Atmospheric Administration.
Johnson offered a couple of caveats regarding the WMO report. The period of observation is only about 30 years, and it's possible that the depletion is simply a symptom of "natural variability."
Ther report certainly wasn't a surprise. NOAA had put out a release last month saying that ozone was thinning up that way, the result of an unusual confluence of circumstances.
About 90 percent of all ozone is in the stratosphere, which is from 6 to 30 miles into the atmosphere, and it protects earthlings from harmful ultraviolent radition.
The ideal conditions for depleting Arctic ozone include a cold stratosphere coinciding with a rising sun and the presence of pollutants, such as chloroflurocarbons.
That's why the transisition from winter to spring is the depletion season in the Arctic, and from summer to fall in the Anarctic. See NOAA's quick summary of the process.
This time around, everything fell into place for ozone depletion in the Arctic, said Johnson, with a cold stratosphere holding service as the seasons changed. "The setup for conditions is just right this year," he said.
The depletion is not going to affect the air over Philadelphia anytime soon, he said. Typically, the depletion zone will shift toward Greenland, Scandinavia and Russia.
As most of the rest of us, ozone levels have their ups and downs. Said Johnson, "It's always going through natural production and destruction cycles."