Antarctic ozone hole getting deeper in mid-spring, research suggests

Recent investigations point to an alarming deepening of the Antarctic ozone rift during the middle of the spring season, occurring over the recent two decades, despite a worldwide cessation of ozone-depleting chemicals usage, a study announced on Tuesday.

Located 11 to 40 kilometers (seven to 25 miles) above the terrestrial surface, the ozone membrane acts as a sieve, filtering the bulk of the sun’s harmful ultraviolet radiation, which is known to induce skin cancer and cataracts.

From the mid-1970s, substances identified as chlorofluorocarbons (CFCs)—previously prevalent in cooling systems and spray cans—were recognized for their erosive effects on ozone levels, culminating in yearly gaps predominantly over the Antarctic territory.

Recognized as an international environmental triumph, the 1987 Montreal Protocol sought to abolish CFCs to mend this gap.

An extensive UN-supported evaluation in January confirmed the effectiveness of the agreement, predicting that the ozone layer would revert to its 1980 condition above the Antarctic around the year 2066.

A quicker resurgence is anticipated for smaller cavities above the Arctic by 2045, and the layer is expected to heal within the upcoming two decades for other regions.

However, even with the decline of CFC emissions, there hasn’t been a noticeable shrinkage in the scope of the Antarctic ozone void, suggested by New Zealand experts in a novel publication within the journal Nature Communications.

Furthermore, they noticed a decrease in ozone concentration at the void’s nucleus over time.

“Out of the past nine years, six have exhibited exceedingly vast ozone rifts coupled with drastically low ozone quantities,” mentioned Annika Seppala from Otago University in New Zealand, conversing with AFP.

“It appears there may be additional phenomena currently occurring within the atmosphere—potentially tied to climate change—which could be obscuring the anticipated recovery,” she elucidated.

A Sequence of Peculiar Years

Ordinarily, the Antarctic ozone layer gap manifests in September, persisting till November, coinciding with the Southern Hemisphere’s spring.

Experts observed the gap’s onset shifting to later in September, hinting at possible recuperation, potentially linked to diminished CFC levels.

Yet come October, traditionally when the rift reaches its peak extent, the report noted a 26 percent contraction in ozone within the middle stratosphere, comparing data from 2004 to 2022, as observed via satellite data.

Hannah Kessenich, the paper’s principal investigator, affirmed that the Montreal Protocol and endeavors to cut down on CFCs are still “on the righteous path.”

“Collectively, our observations indicate that the substantial ozone rifts of late might not be solely attributed to CFCs,” she contributed.

From their analysis, the years 2002 and 2019 were excluded due to “sudden disruptions of the polar vortex” leading to markedly lesser ozone gaps, Kessenich noted further.

Esteemed specialist in ozone research, Susan Solomon, who wasn’t part of the study, proposed that the study’s findings should be considered with the understanding that “the preceding few years have been quite atypical.”

Solomon’s earlier research postulated that the immense “Black Saturday” bushfires in Australia widened the 2020 ozone rift by 10 percent.

The massive outburst of the Hunga-Tonga-Hunga-Ha’apai volcano near Tonga in 2022 is also suspected of impacting recent ozone levels.

Martin Jucker, an authority at Australia’s University of New South Wales, expressed skepticism regarding the conclusions of the study.

“The method of omitting the years 2002 and 2019 from the record seems debatable, given that these, along with the years 2020-22, were all influencing years marked by rare and exceptional events,” he articulated.

© 2023 AFP