According to scientists from NASA and NOAA, warm temperatures in the Antarctic led to a smaller ozone hole this year.
The “hole” in the Earth’s ozone layer forms over Antarctica at the end of each winter in the southern hemisphere. Observations this past September indicate that it was the smallest hole recorded since 1988.
“The Antarctic ozone hole was exceptionally weak this year,” said Paul Newman, chief scientist for Earth sciences at NASA’s Goddard Space Flight Center. “This is what we would expect to see given the weather conditions in the Antarctic stratosphere.”
This year’s hole covered 7.6 million square miles, about 2.5 times the size of the United States.
Discovered in the 1980s
The Antarctic hole was first detected in 1985. Research indicates that when sunlight returns during the late winter, it triggers reactions with human-made, chemically active forms of chlorine and bromine. Consequently, ozone molecules are destroyed.
So what does this mean?
With fewer chlorofluorocarbons (CFCs) in use, scientist predicts that the hole will recover back to 1980 levels by 2070. However, scientists say that the smaller hole recorded this year had more to do with weather conditions than human intervention. Unfortunately, this year’s smaller hole is not a sign of rapid healing.
Why should we care?
The ozone layer is a shield for those of us on Earth. It acts as a natural sunscreen, blocking ultraviolet radiation that can cause skin cancer and cataracts.
Is it a hole?
No, the hole is just what scientists use as a metaphor for the area in which ozone concentrations drop below the historical threshold of 220 Dobson Units.
During the 1960s, long before the hole occurred, average ozone concentrations above the South Pole ranged from 260 to 320 Dobson Units.
“In the past, we’ve seen ozone at some stratospheric altitudes go to zero ozone by the end of September,” said Bryan Johnson, NOAA atmospheric chemist. “This year, our balloon measurements showed the ozone loss rate stalled by the middle of September and ozone levels never reached zero.”
Globally, the ozone layer today ranges from 300 to 500 Dobson units.