New data has revealed the hole in the ozone layer has taken longer than usual to close and was relatively large this year.
‘Unusual’ data from the European Space Agency’s Copernicus Atmosphere Monitoring Service (CAMS) shows the ozone hole has remained larger than usual throughout November and coming to an end well into December.
The Antarctic ozone hole usually starts opening during the Southern Hemisphere spring (in late September) and begins to decline during October, before typically coming to an end during November. Nonetheless, the CAMS data from the last three years shows different behaviour.
CAMS Director, Vincent-Henri Peuch explains: “There are several factors influencing the extent and duration of the ozone hole each year, particularly the strength of the Polar vortex and the temperatures in the stratosphere.
“The last three years have been marked by strong vortices and low temperatures, which has led to consecutive large and long-lasting ozone hole episodes.
“There is a possible connection with climate change, which tends to cool the stratosphere. It is quite unexpected though to see three unusual ozone holes in a row. It is certainly something to look into further.”
The date of the ozone hole closure in 2020 and 2021 was December 28 and December 23 respectively, and scientists expect that this year’s hole will close within the coming days.
The last three ozone holes have been not only exceptionally persistent but also had a relatively large extension. During these three years, the ozone hole has been above 15 million km2 (similar to the size of Antarctica) during most of November.
However, despite these recent fairly large ozone holes, there are consistent signs of improvement of the ozone layer. Thanks to the implementation of the Montreal Protocol, the concentrations of Ozone Depleting Substances (ODS) have been slowly but steadily declining since the late nineties.
It is expected that in 50 years their concentrations in the stratosphere will have returned to the pre-industrial levels and ozone holes will no longer be experienced regardless of Polar vortex and temperature conditions.
Source link
