Less than a month before the start of the "ozone hole season" (the period in which the phenomenon normally occurs), scientists at the Copernicus atmosphere monitoring service (Cams) have released encouraging data. This year, the hole could turn out to be particularly small — reaching one of its lowest readings in the past 30 years.

Copernicus ECMWF @CopernicusECMWF

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🌐How unusual is this year's #Antarctic #OzoneHole?

The chart below shows the hole is forecast to be the smallest one in the #CopernicusAtmosphere Monitoring Service records, which go back to 2003.

More about CAMS' #ozone monitoring & regular updates ➡️bit.ly/2P3nXIb

♥ 10💬 2 6 set 2019 · Apri su X →

The ozone hole will be half the size recorded in 2018

Experts explain that the hole will likely be half the size it was in 2018. Not only that: it will also be "off-centre" and "off-axis". "Forecasts – Cams clarifies – indicate that, after reaching a local minimum last week, the ozone hole could begin to grow gradually again, but it is unlikely to return to the extent seen over the last two or three decades." The estimates were produced in collaboration with the European Centre for Medium-Range Weather Forecasts (Ecmwf), and published on the occasion of the International Day for the Preservation of the Ozone Layer.

The data were extrapolated using satellite observations combined with atmospheric models. "Typically – Cams continues – the ozone hole over Antarctica begins to form every year in August, reaching its maximum size in October, before closing again in December. However, the data reveal that the ozone hole over Antarctica began to form approximately two weeks earlier than predicted and earlier than in previous years."

The 2019 collapse driven by a stratospheric phenomenon

Since the beginning of September, in fact, "the polar vortex (cold air in the stratosphere above the Earth's atmosphere) that provides the conditions for the formation of the ozone hole has shifted and weakened due to a sudden stratospheric warming event. Temperatures in the upper stratosphere are indeed rising to 40 degrees above normal, which is why the polar vortex has been more unstable than usual."

In any case, the overall trend of the ozone hole appears clear. As early as 2016 and in 2018, scientists' observations confirmed that the phenomenon is diminishing: a victory for the Montreal Protocol and international commitment. Proof that when governments act together towards a goal, it can be achieved.

Full recovery will require waiting until 2060

In particular, a report entitled Scientific Assessment of Ozone Depletion – published by the World Meteorological Organization (Omm) and the United Nations Environment Programme (Pnue), together with Noaa, Nasa and the European Commission – had indicated that "since 2000, the ozone layer in certain portions of the stratosphere has been recovering at a rate of between 1 and 3 per cent per decade." Nevertheless, returning to 1970 levels will require waiting until 2060.

UN Environment Programme ✓ @UNEP

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Thanks to the #MontrealProtocol the ozone hole is expected to gradually close, with ozone returning to 1980 values by the 2060s.

We celebrate this and other successes this #OzoneDay: bit.ly/ozoneday2019
#ClimateAction

♥ 711💬 20 16 set 2019 · Apri su X →

Furthermore, Vincent-Henri Peuch, director of Cams, comments: "there is no cause for complacency. The recovery of the ozone layer depends on climate change and on the long-term cooling of the stratosphere, which can exacerbate ozone loss and delay the process. Moreover, the possibility of unauthorised emissions of ozone-depleting substances cannot be ruled out. Indeed, last year the release of chlorofluorocarbon (CFC-11) was revealed. It is very important to maintain a strong international commitment to monitoring the recovery of the ozone layer."