“Significant milestone” reached in ozone layer recovery

“Significant milestone” reached in ozone layer recovery

The Earth’s ozone layer is vital for protecting all forms of life – from crops to humans – from the sun’s harmful radiation. This shield in the Earth’s stratosphere has been depleted for decades, putting life on the planet at risk, but new research from NOAA says there may now be a chance for at least partial recovery.

In new research, NOAA found that global concentrations of the harmful chemicals that damage the ozone layer have decreased by just over 50% in the mid-latitude stratosphere, to levels observed in 1980. The continued decline, said NOAA scientists, “the threat to the ozone layer recedes below a significant milestone in 2022.”

Although slower, concentrations have declined over Antarctica, where a hole in the ozone layer is seen every year. NOAA found that concentrations have decreased by 26% from peak values ​​in the region in the ’90s. In 2021, there was that hole more than usual – larger than the size of Antarctica itself, but now NOAA says the Antarctic ozone layer is projected to recover “sometime around 2070.”

International regulations and compliance management of these chemicals are the reason for the “slow but steady” three-decade progress, the agency said.

Stephen Montzka, senior scientist for NOAA’s Global Monitoring Laboratory, said the progress is great, but “at the same time, it’s a little humbling to realize that science is still a long way from being able to claim that a question the ozone depletion behind. us.”

The Ozone Depleting Gas Index (ODGI) vs.  time calculated for the Antarctic and mid-latitude stratosphere.  As before, the ODGI was derived directly from the Equivalent Effective Serial Chlorine (EESC) determined from our surface atmospheric observations.  / Credit: NOAA

The Ozone Depleting Gas Index (ODGI) vs. time calculated for the Antarctic and mid-latitude stratosphere. As before, the ODGI was derived directly from the Equivalent Effective Serial Chlorine (EESC) determined from our surface atmospheric observations. / Credit: NOAA

Scientists have been closely monitoring the ozone since the 1980s, when certain man-made chemicals were found to have “severely damaged” the Earth’s vital protective layer. In 1987, just seven years after ozone depletion from the most prominent chemicals, every country in the world – for the first and only time ever – ratified a treaty, known as the Montreal Protocol, to regulate the chemicals to protect the Earth defend.

Among those man-made chemical compounds are chlorofluorocarbons (CFCs), which people began using in the 60s in air conditioners, aerosol spray cans, styrofoam and industrial cleaning products, according to the University’s Municipal Corporation for Atmospheric Research.

When used, the CFCs make their way up into the stratosphere, where ultraviolet radiation breaks down the compounds and releases chlorine atoms, which along with bromine, are dangerous to ozone, according to the EPA. These atoms are notorious for destroying ozone molecules – just one chlorine atom can destroy more than 100,000 ozone molecules, the agency said, adding that ozone “can be destroyed faster than it is created natural with these atoms.”

Hydrochlorofluorocarbons (HCFCs) were developed as a temporary alternative to CFCs, because they have a shorter atmospheric lifetime compared to CFCs and do not contribute as much reactive chlorine to the stratosphere. However, they still have the potential to “destroy stratospheric ozone,” according to NOAA, and production was banned in developed countries in 2020.

And while the success so far is promising, scientists said, the fight is not over.

“Ozone layer recovery is not a foregone conclusion,” they said in their report. “Full recovery is expected only with sustained reductions in atmospheric chlorine and bromine in the coming years and continued compliance with the production and consumption restrictions set out in the Protocol.”

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