Worse outlook for Antarctic ozone hole

A new computer model of the Antarctic ozone hole shows it's in worse condition than previously thought.

A hole in the upper atmosphere over Antarctica will not clear up before 2068, roughly 18 years later than earlier estimates, according to a new computer simulation developed by scientists at NASA, the National Oceanic and Atmospheric Administration (NOAA) and the National Center for Atmospheric Research (NCAR). Expectation for the hole to disappear has come from the Montreal Protocol, an international agreement adopted in 1987 that first limited and then banned production of ozone-depleting substances like chlorofluorocarbons (CFCs)--a chemical that causes chlorine and bromine gases that destropy the protective layer of the stratosphere.

In December, scientists at the American Geophysical Union, an annual earth sciences conference, projected that the hole wouldn't return to 1980 levels until 2065. Now, the estimates are even higher.

The ozone layer is critical to life on earth because it protects humans, marine life and the environment from the Sun's harmful ultraviolet rays. The ozone layer blocks between 90 percent to 99 percent of UV rays, which are known to cause skin cancer, eye damage and genetic malfunction.

Using a new mathematical model, the team of scientists was able to recreate what they called an accurate picture of the Antartic ozone hole over the past 27 years. They then projected future output of ozone-depleting substances and were able to predict that the ozone hole will recover in 2068, not in 2050, as previously estimated.

The research also showed that the ozone hole has not yet begun to improve, and the scientists predict that it will not start to significantly shrink until 2018.

""This new method allows us to more accurately estimate ozone-depleting gases over Antarctica, and how they will decrease over time, improving the ozone hole," said Paul Newman, a research scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland and lead author the report.

A report on the subject will be out in next week's Geophysical Research Letters, a journal of the American Geophysical Union.