Massive wildfires in Australia increased Antarctic ozone hole: study

PARIS: Smoke from monster wildfires in Australia caused a chemical reaction that widened the ozone hole by 10 percent, researchers said on Wednesday, stoking fears that escalating wildfires could delay restoring Earth’s atmospheric protection against deadly UV rays.

Severe summer heat and drought helped fuel the deadly “Black Summer” fires of late 2019-early 2020, which destroyed vast swathes of eucalyptus forest and blanketed Sydney and other cities in smoke and ash for months.

Previous research concluded that the more than a million tons of smoke pumped into the atmosphere by the fires was lengthening the Antarctic ozone hole, which opens over Antarctica every spring.

In a new study published in the journal Nature, researchers in the United States and China identified a newly identified chemical reaction in wildfire smoke that enhanced the depletion of ozone — the atmospheric gas that reduces the amount of ultraviolet radiation reaching the surface of the earth.

Susan Solomon, a professor at the Massachusetts Institute of Technology who led the research, said this reaction flaked off the edges of the ozone hole over Antarctica, expanding the hole by more than two million square kilometers (770,000 square miles) — 10 percent of its area compared to the previous year.

“These chemical reactions are happening right at the edge of the region where the ozone hole is occurring,” she said, explaining that the “particles give it a little extra boost.”

The ozone hole was first caused by human pollution — specifically chlorofluorocarbons (CFCs) emitted by many refrigerators — but in recent decades a global deal on these chemicals has given the ozone layer a chance to heal.

The 1987 Montreal Protocol, ratified by 195 countries, greatly reduced the amount of CFCs being pumped into the atmosphere, although the molecules remain for decades.

United Nations modeling predicts that the ozone layer over the southern hemisphere should completely heal by 2060.

But Solomon, who first identified the chemicals responsible for Antarctica’s ozone hole in the 1980s, expressed concern that the effects of climate change could slow that recovery.

“We believe that wildfires are becoming more frequent and more intense,” she told AFP, adding that the ozone hole “will eventually get better I think, but it’s conceivable that wildfires could certainly slow it down.”

“I don’t think it will stop the recovery entirely. But it might prevent it from actually recovering when we think it should.”

– Ozone ‘Shocker’ –

Scientists have long linked the formation of ozone holes to extreme cold because at these very low temperatures, clouds provide a surface for any remaining CFCs to react with and convert them into other chemicals that make the chlorine more damaging to the ozone layer than it would otherwise be case would be.

But Solomon said the new research shows that fire smoke particles that rise into the atmosphere also serve to pick up those molecules and trigger a series of chemical reactions that produce ozone-depleting chlorine monoxide.

They found that this can happen without needing the extremely cold temperatures.

By triggering this response, the new study found that the fires likely contributed to a temporary 3 to 5 percent depletion of total ozone in the mid-latitudes of the southern hemisphere, over Australia, New Zealand and parts of Africa and South America.

“Honestly, I’ve never seen anything like what happened after the Australia fires, and I never expected it,” said Solomon, a leading climate scientist.

“That’s another shocker.”

A study published in August by researchers in the UK found that an accumulation of smoke particles from the Black Summer fires caused changes in atmospheric temperatures that lengthened Antarctica’s ozone hole.

More than 30 people died in the Black Summer fires, which are estimated to have killed or displaced one to three billion animals.

Climate change caused by fossil fuel pollution is expected to result in hotter and drier conditions associated with more intense wildfires.