NASA Ozone Hole September 2008
NASA Image of Ozone Hole, September 2008

 

In September, when cold temperatures and sunlight begin to appear over the Antarctic horizon and start to drive chemical reactions that destroy ozone, the yearly hole in earth’s ozone layer is at its biggest. An important chemical in these reactions is chlorine, which comes from manmade chlorofluorocarbons (CFCs). By October, the ozone-destroying chemical reactions stop. From October to December, the ozone depleted region moves south, so there’s less atmospheric ozone over parts of the USA. NASA’s satellite data shows that this year the ozone hole grew to its largest size on Sept. 13, reaching a maximum area extent of 9.7 million square miles. That’s larger than the area of North America.
NASA scientists say that this size is fairly similar to the sizes observed over the last decade. But it is still huge, particularly when you consider that the ozone hole didn’t exist at all until the 1970’s. Some scientists think that the ozone hole will slowly shrink now that CFC’s are banned by an international treaty. The ozone hole doesn’t appear to be a cause of climate change — instead the hole is caused by some of the same atmospheric gases that cause global climate change. If the hole is closed, some scientists think it will help reduce the warming of Antarctica, so it’s all connected! You can read about the study here:  Mending Ozone Hole