Remember the Ozone hole? Decades ago it was a big concern. It was getting bigger and bigger and our emissions of ozone-depleting substances was identified as the main reason. It continues to get smaller as anthropogenic emissions continue to be reduced. It was slightly smaller in 2013 than average in recent decades, according to NASA satellite data.

The ozone hole is a seasonal phenomenon that starts to form during the Antarctic spring (August and September). The September-October 2013 average size of the hole was 8.1 million square miles (21 million square kilometers). For comparison, the average size measured since the mid-1990s when the annual maximum size stopped growing is 8.7 million square miles (22.5 million square kilometers). However, the size of the hole in any particular year is not enough information for scientists to determine whether a healing of the hole has begun.