Guest post by Tony Brown,
The Ozone Hole returns to both Poles
Some years ago, relating to a project I was carrying out, I asked the Max Planck Institute and Cambridge University –both experts in this field-if it were possible that Antarctic ‘ozone hole’ -actually a ‘thinning’ – existed prior to it being first ‘discovered’ in 1957.
Prior to that date the apparatus did not exist in any convenient form that could measure the likely extent of any hole, should it have existed. This is the official explanation;
“The springtime Antarctic ozone hole is a new phenomenon that appeared in the early 1980s.
The observed average amount of ozone during September, October, and November over the British Antarctic Survey station at Halley, Antarctica, first revealed notable decreases in the early 1980s, compared with the preceding data obtained starting in 1957. The ozone hole is formed each year when there is a sharp decline (currently up to 60%) in the total ozone over most of Antarctica for a period of about three months (September-November) during spring in the Southern Hemisphere. Late-summer (January-March) ozone amounts show no such sharp decline in the 1980s and 1990s. “
Both organisations I approached agreed it was theoretically possible the hole could have existed prior to 1957, but thought it unlikely, as it was proven that refrigerants and other man- made chemicals were the cause of the thinning and it must therefore be a recent problem, as the circumstances that caused it did not exist in the past.
.In 2019 there was a considerable amount of press and government comment that the ‘Hole’ was ‘healing,’ as it was unusually small, said to be due to actions taken by global governments in 1987 who signed the Montreal protocol ;
“The Montreal Protocol on Substances that Deplete the Ozone Layer is the landmark multilateral environmental agreement that regulates the production and consumption of nearly 100 man-made chemicals referred to as ozone depleting substances (ODS). When released to the atmosphere, those chemicals damage the stratospheric ozone layer, Earth’s protective shield that protects humans and the environment from harmful levels of ultraviolet radiation from the sun. Adopted on 15 September 1987, the Protocol is to date the only UN treaty ever that has been ratified every country on Earth – all 197 UN Member States.”
A year on however, there was this surprising announcement from the World Meteorological Organisation, made on 6 October 2020;
“2020 Antarctic ozone hole is large and deep”
“There is much variability in how far ozone hole events develop each year. The 2020 ozone hole resembles the one from 2018, which also was a quite large hole, and is definitely in the upper part of the pack of the last fifteen years or so”, Vincent-Henri Peuch, Director of Copernicus Atmosphere Monitoring Service at ECMWF, said in a news release.
“With the sunlight returning to the South Pole in the last weeks, we saw continued ozone depletion over the area. After the unusually small and short-lived ozone hole in 2019, which was driven by special meteorological conditions, we are registering a rather large one again this year, which confirms that we need to continue enforcing the Montreal Protocol banning emissions of ozone depleting chemicals.”
The Montreal Protocol bans emissions of ozone depleting chemicals. Since the ban on halocarbons, the ozone layer has slowly been recovering; the data clearly show a trend in decreasing area of the ozone hole.”
The size of the 2019 hole is now seen as not being part of a welcome downwards trend that was proving the effectiveness of global measures, but as an ‘unusual’ event. The hole is expected to revert to its ‘natural’ condition by the middle decades of this century. Data on the progression of the ‘hole’ since 1979 can be seen in the left hand panel of this link
The Hole in the Arctic Ozone.
After researching further I note that earlier this year the Arctic hole was the largest on record, according to Nature magazine and Scientific American, exciting and concerning scientists. It was driven by exceptionally cold winter temperature. From “Nature”
Rare ozone hole opens over Arctic — and it’s big” ( 27 March 2020)
“Cold temperatures and a strong polar vortex allowed chemicals to gnaw away at the protective ozone layer in the north.
A vast ozone hole — probably the biggest on record in the north — has opened in the skies above the Arctic. It rivals the better-known Antarctic ozone hole that forms in the southern hemisphere each year.
Record-low ozone levels currently stretch across much of the central Arctic, covering an area about three times the size of Greenland (see ‘Arctic opening’). The hole doesn’t threaten people’s health, and will probably break apart in the coming weeks. But it is an extraordinary atmospheric phenomenon that will go down in the record books.
“From my point of view, this is the first time you can speak about a real ozone hole in the Arctic,” says Martin Dameris, an atmospheric scientist at the German Aerospace Center in Oberpfaffenhofen.
“After looming above the Arctic for nearly a month, the single largest ozone hole ever detected over the North Pole has finally closed, researchers from the European Union’s Copernicus Atmosphere Monitoring Service (CAMS) reported.
“The unprecedented 2020 Northern Hemisphere ozone hole has come to an end,” CAMS researchers tweeted on April 23.”
The Montreal protocol was seen as the global template for the Kyoto protocol on CO2 emissions adopted in 1997 and which entered into force in 2005 and the subsequent Paris agreement, a global attempt to curb CO2 emissions and limit temperature rises to 1.5C above pre industrial. Like the ozone hole, CO2 emissions seem surprisingly robust and any reduction in its rate of increase following the sharpest lockdown on human activity since the industrial revolution is difficult to discern at present.
Sept 2020 411.29ppm
Sept 2019 408.54ppm
Updated 6th October 2020
There is a useful link from here entitled “Can we see a change in the record because of covid19” indicating that “The International Energy Agency expects global CO2 emissions to drop by 8% this year. Clearly, we cannot see a global effect like that in less than a year.”
Only time will tell if Man’s culpability in both these important areas is greater or lesser than currently thought.
Tony Brown (tonyb) October 2020