Smoke from recent wildfires threatens to slow and even reverse the recovery of the Earth’s ozone layer — the very layer the world has been working hard to thin since 1987.
The ozone layer is an important part of the stratosphere that protects our planet from sunburn.
It is important that the health of all plants and animals remain intact, but due to the historical use of synthetic pollutants called chlorofluorocarbons (CFCs), a large ancient hole has been created in the Earth’s atmospheric shield over Antarctica.
Thanks to the international agreement to ban CFCs in 1987, the ozone hole is gradually shrinking. In 2019, the hole was the smallest since 1982, when it was first discovered. This is one of the greatest success stories of mankind. But this is not the end.
And in 2021, the hole over Antarctica is starting to swell again, a year after massive, devastating fires burned 60 million acres of vegetation in Australia.
Perhaps this is not accidental.
And a new study of recent large fires in Australia has found that smoke particles in the stratosphere can deplete the ozone layer for over a year. As the particles age, they can become more destructive.
The findings help explain why there is such a delayed effect on ozone layer thickness after wildfire activity.
The 2019/2020 Australian fires released over a million tons of smoke into the atmosphere.
However, it was not until August 2020 that scientists noticed that the ozone hole was growing rapidly.
The researchers estimate that by September, smoke particles had expanded the ozone hole by about 2.5 million square kilometers, up 10% from the previous year.
“The 2020 Australian fires were a wake-up call to the scientific community,” says MIT climate scientist Susan Solomon, who has been working on ozone depletion for decades. Depends on whether fires become more frequent and intense as the planet warms up.”
In the past two decades alone, four of the largest wildfires in human history have occurred in both hemispheres.
And in 2022, Solomon and her colleagues showed that smoke from wildfires can lead to lower levels of nitrogen dioxide in the stratosphere, essentially setting in motion a domino effect that eventually leads to chemical depletion of the ozone layer.
“If you have less nitrogen dioxide, you need more chlorine monoxide, and that will deplete the ozone layer,” Solomon explained at the time. “But this does not explain all the changes observed in the stratosphere. the whole bunch. “Because of the chlorine chemistry that got out of control.”
So Solomon and her team took a closer look at chemical reactions. Using satellite data, they tracked conditions in the stratosphere over Antarctica in the months following the Australian fires.
First, they saw a decrease in hydrochloric acid (HCl) in the atmosphere and an increase in chlorine monoxide. The implication is that hydrochloric acid somehow dissociates, allowing chlorine to freely bind to oxygen and destroy the ozone layer.
In simulations, this effect caused wildfire smoke.
“These are old smoke particles that absorb a lot of hydrochloric acid,” says Solomon. “And then you get, amazingly, the same reactions as in the ozone hole.”
This is a bad sign in the face of the climate crisis. If wildfires become so frequent that the ozone does not have time to recover from the harmful effects of smoke, it can easily resume. Especially since emissions of banned CFCs have been detected and have been increasing over the past few years.
As long as we want to thrive on Earth, we will need the ozone layer to survive.
The study is published in the journal Nature.
Source: Science Alert
