Everywhere you look these days, it seems like there's bad news about the environment. From shrinking glaciers to great garbage patches found in the ocean, it can be difficult to find any good news about the state of the world.
However, there is one piece of good news humanity can celebrate - scientists with NASA say the hole in the ozone layer near the South Pole has shrunk to its smallest size in history. However, that's more due to some freakish weather in the Southern Hemisphere than any effort to cut down on pollution.
According to a release from NASA scientists, the average size of the hole in the ozone layer fell to 3.6 million square miles, down from a peak of 10.3 million square miles in 2006. In fact, this year's hole is even smaller than when it was first discovered back in 1985.
“It’s great news for ozone in the Southern Hemisphere,” said Paul Newman, chief scientist for Earth Sciences at NASA's Goddard Space Flight Center in Greenbelt, Maryland. “But it’s important to recognize that what we’re seeing this year is due to warmer stratospheric temperatures. It’s not a sign that atmospheric ozone is suddenly on a fast track to recovery.”
The ozone layer, located around 7 to 25 miles above the Earth's surface, acts as a kind of protective layer for life on the surface, as it absorbs potentially harmful ultraviolet radiation that can cause skin cancer, cataracts, as well as suppress immune systems and damage plant life. Man made chlorine compounds, such as chlorofluorocarbons that used to be use for refrigeration, can eat away at the ozone layer, depleting the layer and allowing the deadly radiation in.
However, this year, scientists say a rare atmospheric phenomenon brewing above Antarctica over the last few months made it tougher for the chlorine compounds to convert into the chemical that eats ozone. The southern polar vortex began to breakdown in September and October, with the vortex's winds dropping from an average speed of 161 mph to a mere 67 mph, NASA said. Temperatures recorded 12 miles above the Earth's surface, were also far warmer than average at 29 degrees.
“It’s a rare event that we’re still trying to understand,” said said Susan Strahan, an atmospheric scientist with Universities Space Research Association, who works at NASA Goddard. “If the warming hadn’t happened, we’d likely be looking at a much more typical ozone hole.”
NOAA scientists at the South Pole take measurements of the ozone hole by launching weather balloons carrying ozone-measuring "sondes," which directly sample the amount of ozone present in the atmosphere.
“This year, ozonesonde measurements at the South Pole did not show any portions of the atmosphere where ozone was completely depleted,” said atmospheric scientist Bryan Johnson at NOAA’s Earth System Research Laboratory in Boulder, Colorado.
Scientists say this is the third time in the last 40 years of observations that warm temperatures have limited ozone depletion. Generally, the hole reaches its largest size in September and October, and then disappears in late December until spring occurs in the Southern Hemisphere.
In 1987, every nation in the world signed the International Montreal Protocol, which banned many of the chlorine compounds found in refrigerants and aerosols, responsible for eating away at the ozone layer. Over the last thirty years since the ban, the ozone hole above the South Pole has shrunk slight, but scientists say this year's dramatic shrinking has more to do with the weather than the aerosol ban.