The 2015 Antarctic ozone hole area was larger and formed later than in recent years, accorrding to a new paper. On Oct. 2, 2015, the ozone hole expanded to its peak of 10.9 million square miles, an area larger than the continent of North America.
Throughout October, the hole remained large and set many area daily records. Unusually cold temperature and weak dynamics in the Antarctic stratosphere this year resulted in this larger ozone hole.
In comparison, last year the ozone hole peaked at 24.1 million square kilometers (9.3 million square miles) on Sept. 11, 2014. Compared to the 1991-2014 period, the 2015 ozone hole average area was the fourth largest.