Ozone hole could've been a big one this year – but it wasn’t
02 November 2018
The ozone hole that forms over the Antarctic each September is primarily driven by two factors: the amount of ozone-destroying chlorine in the polar stratosphere and the availability of ice crystals in stratospheric clouds for the chlorine to bind to.
This year, the super-cold stratospheric temperatures measured by NOAA and NASA meant conditions were ripe for the development of ice clouds - and a big ozone hole.
But the size of the 2018 ozone hole seen by NASA satellites was just a little larger than average, covering 8.83 million square miles (almost three times the size of contiguous United States). That's because chlorine levels have been falling thanks to a 30-year-old global environmental treaty known as the Montreal Protocol.
Image credit: Robert Schwarz/University of Minnesota - The view of total ozone over the Antarctic pole from October 24, 2018. The purple and blue colors are where there is the least ozone, and the yellows and reds are where there is more ozone.