The 1980s Continue to Haunt Us Through the Hole in the Ozone Layer

A supplied image shows birds flying above icebergs in Antarctica, December 19, 2006. Reuters

The ozone hole over Antarctica is the smallest it has been since 1988, scientists announced on Thursday.

The ozone hole, which forms over the icy continent each September, was measured at its peak this year on September 11 over an area two and half times the size of the U.S., said NASA. From then on, the size declined throughout September and into October.

An unstable and warmer Antarctic vortex minimized polar stratospheric cloud formation in the lower atmosphere. That essentially led to fewer clouds, which are the first steps that lead to chlorine- and bromine-catalyzed reactions that destroy ozone, according to National Oceanic and Atmospheric Administration.

"This is what we would expect to see given the weather conditions in the Antarctic stratosphere," Paul A. Newman, chief scientist for earth sciences at NASA's Goddard Space Flight Center in Greenbelt, Maryland, said in a press release.

The conditions mimicked those in the Arctic, where there is less ozone depletion.

NASA and NOAA worked together to monitor the ozone hole using three instrumental methods: satellites, weather balloons, and a spectrophotometer, which measures the amount of ozone in a column stretching from Earth's surface to the edge of space.

The spectrophotometer measures ozone in Dobson units, with the Earth's average ozone layer at 300 to 500. That's equivalent to two stacked pennies, according to NOAA. Each year, certain regions often drop to zero Dobson units, where the ozone layer has completely disappeared.

"This year our balloon measurements showed the ozone loss rate stalled by the middle of September and ozone levels never reached zero," Bryan Johnson, NOAA atmospheric chemist, said in a press release.

Adelie penguins stand atop a block of melting ice on a rocky shoreline at Cape Denison, Commonwealth Bay, in East Antarctica, January 1, 2010. Reuters

Despite the shrinking ozone hole, chlorine and bromine levels are still high enough to produce significant ozone loss. The shrinkage is due to natural variability—not rapid healing—according to NOAA.

Scientists expect a full recovery back to 1980 standards by 2070.

Each winter in the Southern hemisphere, the ozone hole forms as the sun causes chemical reactions that burn up the ozone. The hole was first discovered in 1985, and the Montreal Protocol on Substances that Deplete the Ozone Layer was founded by the end of the decade to solve the problem.

But in a study published last month, scientists found that there were previously unrecognized chemicals still damaging the ozone layer, despite several that have been banned.

Ozone—a molecule made of three oxygen atoms—shields Earth from ultraviolet radiation that can cause skin cancer and cataracts, suppress immune systems, and damage plants