Natural fires damage the ozone layer

(ORDO NEWS) — Scientists have shown that soot particles from powerful fires, reaching the lower stratosphere, destroy active nitrogen molecules, leaving the ozone layer unprotected.

In the lower layers of the stratosphere, at altitudes of 20 to 40 kilometers, it is saturated with ozone, which is formed from molecular oxygen, absorbing the soft ultraviolet of the sun.

Ozone itself absorbs photons of hard ultraviolet light, turning back into molecular oxygen. This is how the ozone layer works , which protects the surface of the planet from deadly radiation.

At the end of the 20th century, scientists noticed that the ozone layer was being depleted due to the active use of freon and other halogen-containing organic substances.

They managed to convince the world community of the reality of this threat, and after the adoption of the Montreal Protocol, their production and use were banned, and the ozone layer began to recover rapidly . However, in recent years, this process has stalled, and climate change is causing a new blow to ozone.

Global warming makes vast regions of the planet very hot and dry, which has already led to a noticeable increase in wildfires.

In 2019-2020, they covered more than 24 million hectares in Australia and raised about a million tons of smoke and soot particles into the air, which reached a height of up to 35 kilometers, right up to the upper limit of the ozone layer.

Susan Solomon of the Massachusetts Institute of Technology (MIT) and her colleagues used satellite data to track the impact of Australian fires on the composition of the atmosphere, as well as computer simulations.

They showed that in March 2020 – shortly after the flame went out – the content of nitrogen dioxide in the stratosphere fell to a record level in decades.

These changes signal chemical reactions that the smoke and soot set off high in the air. Normally, under the action of sunlight, nitric oxide (V) is converted there into nitric oxide (IV), which quickly reacts with chlorine and other halogens, preventing them from destroying ozone molecules.

However, when soot particles appear, this mechanism weakens. The soot reacts with nitric oxide (V), converting it to nitrate, and there is too little dioxide left, allowing the chlorine to do its destructive work.

According to Solomon and her co-authors, the Australian fires have reduced the ozone concentration by about a percent.

Given that its replenishment in the stratosphere occurs at a rate of one to three percent per decade, a natural disaster in Australia alone “zeroed out” several years of natural recovery. And that’s not counting the roughly 788 million tons of carbon dioxide that were released into the air.

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