Antarctica’s ozone hole is surprisingly large for December, say scientists – Observatory of Europe after No

What is causing the Antarctic ozone hole to open and why is it larger than usual this time of year?

According to climatologists, the ozone hole that forms over Antarctica every year is taking an unusually long time to close.

Typically, the Antarctic ozone hole begins to form in mid-August and begins to gradually diminish in November.

But this year the ozone hole formed several days earlier than usual and has maintained an area of ​​just over 15 million square kilometers since the end of October. The alarming news comes from the Copernicus Atmosphere Monitoring Service (CAMS), which is closely monitoring the hole.

Why is the ozone layer so important?

The ozone layer on Earth protects us all from the sun’s harmful rays. The realization that some chemicals dilute it led to a major international intervention in 1987.

The Montreal Protocol – signed just seven years after the problem was discovered – is a rare example of rapid global agreement and is the envy of today’s climate scientists.

The treaty phased out man-made chemicals that deplete ozone molecules from the atmosphere, prompting scientists to announce a “milestone” in replenishing the ozone layer last year.

But for the past three years, the ozone layers have been closing much later than usual. According to CAMS, climate change is one of the possible causes of this phenomenon.

How has the Antarctic ozone hole changed in 2023?

The ozone hole widens in the southern spring when ozone-depleting substances begin to accumulate in the stratosphere above the South Pole. Combined with solar radiation, extremely cold temperatures and polar stratospheric clouds, this leads to a drastic drop in ozone concentration in the stratosphere.

In late November, the stratospheric temperature rises and a change in wind tends to shrink the hole in the ozone layer.

The year 2023 was a little different. Due to an earlier increase in size, the ozone hole was the sixth largest in the satellite era (since 1979), with a total area of ​​25.12 million km2 (as of mid-September).

Despite a usual decline through early October, it rose again toward the end of the month, CAMS notes. And it has maintained an area of ​​about 12 million km2 and is expected to remain so until the first week of December.

Why does it take longer for holes in the ozone layer to close?

Although the ozone hole has waxed and waned in unique ways this year, this unusual longevity is part of a current trend.

Since 2020, holes in the ozone layer have been dissipating much later than before, around mid to late December.

According to CAMS, this is due to colder than average stratospheric temperatures and a strong polar vortex – strong winds circulating high in the atmosphere over Antarctica – that lasts until December.

The reason for this stronger polar vortex still remains a mystery. CAMS has identified several potential factors, including water vapor released into the atmosphere from the Hunga-Tonga volcano in the South Pacific; changes in wind patterns in the Southern Hemisphere; and climate change.

According to the monitoring service of the European Center for Medium-Range Weather Forecasts, commissioned by the European Commission, further research is needed.

“Since signing the Montreal Protocol, we have significantly reduced emissions of ozone-depleting substances and given the atmosphere the space to begin its recovery,” says Vincent-Henri Peuch, Director of CAMS.

“This is a long process that involves many fluctuating factors that need to be monitored to fully understand how the ozone layer is evolving. The success of the Montreal Protocol shows the effectiveness of measures to protect the global climate. »