The elliptical hole in the ozone layer over Antarctica is back, and it is already twice the size of Europe, the World Meteorological Organization (WMO) reports. An annual feature of the austral spring for at least the past few decades, the ozone hole “appeared earlier than in recent years” and had already grown to 20 million km2 by the week of September 24–30, researchers from the WMO told Reuters.
The largest ozone hole on record formed in 1995, when the gap in Earth's ultraviolet radiation-blocking layer expanded to 22 million km2. Atmospheric concentrations of ozone over the South Pole dipped as low as 129 Dobson units in 1995, and this year's hole has already shown Dobson values below 180, a 45% decline from the normal ozone shield. The total ozone minimum over Antarctica is typically observed in mid-October.