Earth’s ozone layer to heal within decades: UN report


SINGAPORE – In a rare piece of good news for the environment, a United Nations-backed panel of experts has stated that the earth’s ozone layer is set to recover within decades.

The report, released on Jan 9 by the World Meteorological Organisation, the UN Environment Programme and other American and European organisations, noted that ozone levels around the world, excluding polar regions, would return to 1980 levels around 2040.

As for the Arctic and Antarctic, ozone levels would recover around 2045 and 2065 respectively.

Commenting on these findings, Associate Professor Adrian Michael Lee of the Department of Chemistry at the National University of Singapore said the return of total column ozone (TCO) to 1980 levels means that the ozone layer would have been restored to the state before the appearance of the Antarctic Ozone Hole, first discovered in 1985.

TCO is a measurement of the total amount of ozone in a given column of the atmosphere stretching from earth to space.

Because the ozone layer prevents harmful ultraviolet radiation from reaching the earth’s surface, a return of TCO to 1980 levels signifies an abatement of the increased risk of skin cancer for people living in temperate latitudes, though it does not make as big an impact to equatorial locations like Singapore, said Associate Professor Koh Tieh Yong. He is a weather and climate scientist at the School of Science and Technology at the Singapore University of Social Sciences.

The report linked the recovery of the ozone layer to the successes of the Montreal Protocol, which was adopted in 1987. It regulates the production and consumption of nearly 100 chemicals known as ozone depleting substances (ODS).

These ODS include chlorofluorocarbons (CFC) which are commonly used in refrigerants and aerosol sprays.

When these substances enter the stratosphere, they set off a series of chain reactions that break down the ozone layer. In addition, many ODS are greenhouse gases that exacerbate climate change.

In 2016, countries also adopted the “Kigali Amendment” to the Montreal Protocol, which committed them to reduce the production and consumption of hydrofluorocarbons (HFC). Though they do not cause ozone depletion, they too are powerful greenhouse gases and contribute to global warming, added Prof Lee.

The report noted that by phasing down ODS and HFC, the protocol has helped to avoid an additional 0.5 – 1 deg C of global warming, as compared to an extreme scenario where emission levels increased by 3 – 3.5 per cent each year.

As a signatory to the treaty, Singapore has implemented control measures. For example, from 2022, the National Environment Agency banned the supply of chillers and air-conditioners that used certain climate-unfriendly HFC refrigerants.

However, the report also highlighted certain outstanding scientific and policy challenges. Though 99 per cent of banned ODS have been phased out, emissions of certain CFC and other gases such as nitrous oxide (N2O) have increased. N2O is not currently regulated under the Montreal Protocol.

Said Prof Lee: “Overall, the global community has made great strides to eliminate the consumption and production of ozone depleting substances. There remains an enforcement issue in certain countries, notably China.”

“The Chinese government has faced significant challenges enforcing regulations that ban the use of CFC and other ozone depleting substances,” he added.

“Observations suggest that those challenges still exist, but hopefully they will be resolved. The international community needs to stay vigilant and ensure that member countries meet their obligations under the protocol,” he said.

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