Nature: Australia’s bushfires may have increased the ozone hole

A severe drought in 2019 created an unprecedented intensity of wildfires. Over 5.8 million hectares were destroyed. In addition to causing catastrophic damage, the fires created plumes of smoke in the atmosphere and raised temperatures in Australia’s lower stratosphere by 3 degrees.

So says the magazine Nature And so suggests a new research report published last week in Scientific Reports.

Globally, temperatures in the lower stratosphere also rose by 0.7 degrees, the largest increase since the 1991 eruption of Mount Pinatubo in the Philippines, sending ash into the atmosphere. The rise in temperature lasted for about four months.

– The effect was similar to the type of impact we would see from a moderate volcanic eruption. “What we’re finding about the scale of these fires is remarkable,” says Nerili Abram, a climate scientist at the Australian National University in Canberra.

Smog for months

The stratosphere extends between about 10 and 50 kilometers above the Earth’s surface. Smoke particles don’t normally reach that far, but smoke from the Australian fires reached heights of more than 35 kilometers.

Clouds contain black carbon, which absorbs heat and rises in the lower stratosphere like a hot balloon, said Jim Heywood, an atmospheric scientist at the University of Exeter in England.

Once there, black carbon absorbs sunlight and heats the air.

The ozone hole may have increased

The study suggests that chemical reactions between smog and ozone in the atmosphere may have caused the ozone hole in Antarctica to become larger, although that link is not entirely clear.

– The year before the fire, we had a small ozone hole. But in 2020, we were surprised by a deep hole that lasted five months, says researcher Jim Heywood of the University of Exeter in England, one of the authors of the study.

When the ozone layer is damaged, the sun’s radiation reaches the earth, affecting the environment and human health. Warming of the stratosphere could damage the ozone layer, but the researchers say more research is needed to determine how smoke from wildfires and ozone interact.