Epic bushfires in Australia have enlarged the ozone hole and caused a global heat wave

(ORDO NEWS) — Smoke from the unprecedented wildfires of 2020 raised temperatures in the stratosphere by up to 3°C in some places.

Smoke from the massive wildfires that raged across southeast Australia in 2019-20 caused a spike in atmospheric temperatures and may have widened the hole in the ozone layer, study says1.

An extreme drought in 2019 led to bushfires of unprecedented intensity, burning over 5.8 million hectares. In addition to causing catastrophic damage, the fires created plumes of smoke that rose into the atmosphere and raised temperatures in the lower stratosphere over Australia by 3°C.

Globally, temperatures in the lower stratosphere have risen by 0.7°C, the biggest increase since the 1991 eruption of Mount Pinatubo in the Philippines, which sent an ash plume into the atmosphere, according to a study published Aug. 25 in the journal Scientific Reports. The rise in temperature continued for about four months.

According to paleoclimatologist Nerili Abram of the Australian National University in Canberra, “the effect was equivalent to what we see with a moderate volcanic eruption.” “What we’re learning about the scale of these fires is amazing.”

Smoke in the stratosphere

The stratosphere is located at an altitude of about 10 to 50 kilometers above the Earth’s surface. Smoke particles do not normally enter the stratosphere, but smoke from the Australian wildfires has reached heights of over 35 kilometers thanks to unusual pyrocumulonimbus clouds caused by the fire.

These smoke-filled storm clouds contain a lot of black carbon, which absorbs heat and rises into the lower stratosphere like a balloon, says study co-author Jim Heywood, an atmospheric scientist at the University of Exeter, UK. Once there, the black carbon continues to absorb sunlight and warm the air.

“There were parts of the coastline that were hazy for months on end,” says Abram. “The scale of this bushfire season has just gone through the roof.”

Haywood and his team used data from polar orbiting and remote sensing satellites to observe changes in the distribution of smoke particles in the stratosphere and combined this information with climate models.

They found that the effects of smoke particles on stratospheric temperature predicted by the models matched observed temperature spikes.

Previous studies2 have used models to model the duration and extent of warming after fires, but this study includes a global analysis, conclusively attributing the temperature increase to bushfire smoke, Haywood says.

“This really puts another nail in the coffin,” says Claire Murphy, an atmospheric chemist at the University of Wollongong in Australia. She says the work builds on earlier research, “expanding the evidence.”

Damaged ozone layer

The models also showed that chemical reactions between smoke and ozone in the atmosphere exacerbated the Antarctic ozone hole, making it even bigger.

“We had a small ozone hole a year before the fires,” Haywood says. “In 2020, we were stunned because a very, very deep ozone hole had formed.” According to him, the hole lasted about five months.

The depletion of the ozone layer strengthens the south polar vortex – an area of ​​low pressure and cold air over the South Pole.

This creates a feedback loop: the stronger the polar vortex, the more it destroys the surrounding ozone and the longer the hole remains open.

When the ozone layer is destroyed, more radiation from the Sun enters the Earth, harming the environment and human health. Warming in the stratosphere can also damage the ozone layer by changing the dynamics of the atmosphere.

Exactly how wildfire smoke and ozone interact remains a mystery due to the complex chemical cocktail in smoke. Climate change is expected to increase the frequency and severity of wildfires, which is why Haywood stresses that it’s important to figure out how smoke and fires will affect the ozone layer.


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