Credit: earthhow.com
At least one expert was ‘not convinced’ by the study’s results. The theory that the ozone hole’s seasonal size was/is strongly related to human activity is left looking a bit threadbare, even if the study doesn’t exactly say that. But if the alleged cause has been mostly removed and the hole persists, to a significant extent at least, what other conclusion is there? ‘Rare events’ is one suggestion.
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The hole in the Antarctic ozone layer has been getting deeper in mid-spring over the last two decades, despite a global ban on chemicals that deplete Earth’s shield from deadly solar radiation, new research suggested Tuesday.
The ozone layer 11 to 40 kilometers (seven to 25 miles) above Earth’s surface filters out most of the sun’s ultraviolet radiation, which can cause skin cancer and cataracts, says Phys.org..
From the mid-1970s, chemicals called chlorofluorocarbons (CFCs)—once widely used in aerosols and refrigerators—were found to be reducing ozone levels, creating annual holes largely over the Antarctica region.
The 1987 Montreal Protocol, which banned CFCs in a bid to close the hole, is considered a success story for international environmental cooperation.
In January, a major UN-backed assessment found that the agreement was working. It projected the ozone layer should be restored to 1980 levels over the Antarctic by around 2066.
Smaller holes over the Arctic were projected to recover by 2045, and for the rest of the world in around two decades.
But despite the decline in CFCs, there has not yet been a significant reduction in the area covered by the Antarctic ozone hole, according to New Zealand researchers behind a new study in the journal Nature Communications.
And there has been less ozone at the center of the hole over time, they added.
. . .
Martin Jucker, an expert at Australia’s University of New South Wales, was not convinced by the study’s results.
“It is questionable how the authors can remove 2002 and 2019 from the record but not 2020-22, given that all of these years have been shown to be dominated by very special and rare events,” he said.
Full article here.
via Tallbloke’s Talkshop
November 26, 2023 at 02:03PM
Iowa Climate Science Education 