“Significant milestone” achieved in the recovery of the ozone layer

“Significant milestone” achieved in the recovery of the ozone layer

The earth’s ozone layer is essential to protect all forms of life, from crops to humans, from the harmful radiation of the sun. 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 it may now have a chance to recover at least in part.

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

Although slower, there has also been a decline in concentrations over Antarctica, where a hole appears in the ozone layer every year. The NOAA found that concentrations dropped 26% from the highest values ​​in the region in the 1990s. In 2021, that hole was there bigger than usual – larger than the size of Antarctica itself, but now NOAA says the Antarctic ozone layer is expected to recover “around 2070”.

International regulations and compliance for handling these chemicals are the reason for the “slow but steady” progress of three decades, 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 say that the problem is. of the exhaustion of the zones is behind us. “

The Ozone Depleting Gas Index (ODGI) compared to the time calculated for the Antarctic and mid-latitude stratosphere.  As before, the ODGI derived directly from the equivalent stratospheric chlorine (EESC) determined by our observations on the atmospheric surface.  / Credit: NOAA

The Ozone Depleting Gas Index (ODGI) compared to the time calculated for the Antarctic and mid-latitude stratosphere. As before, the ODGI derived directly from the equivalent stratospheric chlorine (EESC) determined by our observations on the atmospheric surface. / Credit: NOAA

Scientists have been closely monitoring ozone since the 1980s, when it was discovered that some man-made chemicals were “severely damaging” the Earth’s vital protective layer. In 1987, just seven years after ozone depletion from chemicals became more evident, every country on Earth, for the first and only time ever, ratified a treaty, known as the Montreal Protocol, to regulate chemicals to protect the Earth.

Among these man-made chemicals are chlorofluorocarbons (CFCs), which people began using in the 1960s in air conditioners, aerosol cans, polystyrene, and industrial cleaning products, according to the University Corporation for Atmospheric Research.

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

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

And while success so far is promising, scientists said, the fight isn’t over.

“The recovery of the ozone layer is not a foregone conclusion,” they said in their report. “Full recovery is expected only with a sustained decline in atmospheric chlorine and bromine in future years and continued compliance with the production and consumption restrictions outlined in the protocol.”

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