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Friday, July 10, 2020

Smallest ozone hole in decades: how it happened, why it matters

The annual ozone hole reached its peak extent of 16. 4 million sq km on September 8, then shrank to less than 10 million sq km for the remainder of September and October, satellite measurements show.

By: Express News Service | New Delhi | Updated: October 24, 2019 5:47:54 am
china, environment, chinese government, ozone layer, ozone depleting substance, air conditioners, environmental investigation agency, eia, montreal protocol, cfcs, chluorofluorocarbons, world news, indian express news While it is good news, NASA has cautioned it is important to recognise that what we are seeing this year is not a sign that atmospheric ozone is suddenly on a fast track to recovery.

During September and October, the ozone hole over the Antarctic has been the smallest observed since 1982, NASA and US National Oceanic and Atmospheric Administration (NOAA) scientists have reported. The annual ozone hole reached its peak extent of 16. 4 million sq km on September 8, then shrank to less than 10 million sq km for the remainder of September and October, satellite measurements show. NASA has described it as great news for the Southern Hemisphere.

WHAT IS OZONE HOLE: Ozone, made up of three oxygen atoms, occurs naturally in small amounts. Roughly 10 km to 40 km up in the atmosphere (the layer called the stratosphere), the ozone layer is a sunscreen, shielding Earth from harmful ultraviolet radiation. On the other hand, close to the surface, ozone created as a byproduct of pollution can trigger health problems such as asthma and bronchitis.

Manufactured chemicals deplete the ozone layer. Each spring over Antarctica (it is now spring there), atmospheric ozone is destroyed by chemical processes. This creates the ozone hole, which occurs because of special meteorological and chemical conditions that exist in that region.

Average area of ozone hole, in million sq km, for the period between September 7 and October 13. No data for the 1995 season. (Source: NASA)

WHY IT’S SMALL THIS YEAR: There have been abnormal weather patterns in the atmosphere over Antarctica. In warmer temperatures like this year, fewer polar stratospheric clouds form and they don’t persist as long, limiting the ozone-depletion process. While it is good news, NASA has cautioned it is important to recognise that what we are seeing this year is not a sign that atmospheric ozone is suddenly on a fast track to recovery. —(Source: NOAA)

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