Ozone layer hole might be mending, says NASA

Ozone layer hole might be mending, says NASA

Ozone layer hole might be mending, says NASA

New NASA study offers first direct proof that the ozone hole is recovering thanks to the Montreal Protocol treaty and the global ban on CFCs.

Since 2005, NASA scientists have used the Aura satellite to measure ozone depletion rates during the winter months.

About 30 years since the Montreal Protocol was signed, which prohibited using ozone-destroying chemicals, NASA scientists say they have hard proof the hole in Earth's ozone layer is shrinking. When they rise to the stratosphere, they are broken down by ultraviolet solar radiation, releasing chlorine, which eats away at the ozone layer. Hydrochloric acid is a chemical that forms once chlorine has destroyed the ozone itself.

The yearly changes in the ozone hole, which is positioned over Antarctica, are the result of variations in weather patterns and seasonal changes that can either help the ozone recover or aid in the chemical reactions that break it down further.

The ozone layer acts as a protective shield around the Earth, absorbing the Sun's harmful ultraviolet radiation which can cause cancers, suppress the immune system in humans and damage plant life. Fast-forward decades later, and the ozone hole was measured at the smallest since 1988, NASA announced last November.

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Hailed as an example of how concerted global action can help solve a planetary crisis, a new study conducted by NASA scientists documented the first direct evidence that an worldwide effort to ban chlorofluorocarbons (CFCs) has led to the recovery of the Antarctic ozone hole. By measuring hydrochloric acid levels each fall, scientists were able to gauge the amounts of chlorine in the ozone hole. "This gives us confidence that the decrease in ozone depletion through mid-September shown by [Microwave Limb Sounder] data is due to the declining levels of chlorine coming from CFCs".

"This is very close to what our model predicts we should see for this amount of chlorine decline", Strahan said.

The MLS measures microwave emissions and trace gases over the Antarctic.

There is still a long way to go for a complete recovery. Measurements in the past have shown that the hole was shrinking, leading to premature celebration that humanity had done something good for once, only to discover the following year that the hole was once again larger.

The hole in the ozone layer is getting smaller and smaller. "But we're not yet seeing a clear decrease in the size of the ozone hole because that's controlled mainly by temperature after mid-September, which varies a lot from year to year".

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