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Where the smoke of Australia dies



Smoke from Australia's mega-fires has traveled tens of thousands of kilometers around the world. "It will circle the world in about a week," said Manvendra Dubey, who studies air pollution and devastating smoke at the Los Alamos National Laboratory.

Hundreds of flames in Alaska, the Amazon and the Arctic Circle have also blown thick clouds of smoke into the atmosphere in the past six months. These vapors – a mixture of burned particles and invisible gases – gradually dissolve and finally seem to disappear naturally. After all, after eons of forest fires and volcanic eruptions, the atmosphere is not comparable to the hazy air that accumulates in a smoky bar.

Rebecca Buchholz, an expert on air quality and devastating smoke at the National Center for Atmospheric Research (NCAR), "felt this way in Canberra [Australia] for over two weeks," she said, who recently returned from a visit to Australia's capital , It was a smoky journey.

But where does the smoke ultimately go?

Broadly speaking, there are two components to wildfire smoke: the stuff you can see and the stuff you can't see. Everyone is bad for various reasons. Let's start with the visible things spied on by the Australian smoke satellites over the Pacific Ocean.

Visible smoke

When bushfires burned rubber trees and eucalyptus in large parts of the valued Australian Wollemi National Park ̵

1; which is currently closed to fire – the charred remains of these plants flew into the air as tiny particles known as particles or aerosols ,

This visible air pollution from Wollemi and many other parched bushlands in southeastern Australia is easily transported by prevailing winds. These particles have clogged the air in the nation's three most populous cities, Sydney, Melbourne and Brisbane, a total population of approximately 12.5 million people. The pollution, sometimes only 65 miles (in the case of Sydney), creates a terrible breathing environment. "There is a serious direct impact on air quality," said Mark Parrington, senior scientist at the European Union's Copernicus Atmosphere Monitoring Service.

Inhaling particles doesn't just harm your lungs. It is bad for your heart. Scientists have repeatedly shown that breathing this material is associated with an acceleration of plaque formation in the arteries. And that's not all. There is growing worrying evidence that inhaling the smallest particles increases the risk of dementia and Alzheimer's.

Fortunately, winds clear the air (at some point). Most of these particles, which often appear as a brownish haze from space, are thrown into the troposphere about five to six miles (the lowest part of the atmosphere where weather such as clouds, rain, cyclones and more occur).

And up here most of this visible smoke will soon come to an end.

"The aerosol particles in the smoke stay in the atmosphere for about five to seven days," said Faye McNeill, who at Columbia University researches the chemistry of the atmosphere and air quality.

Many of these smoke particles would encounter rain and be washed to the surface with drops of water. Other particles slowly fall to the ground due to gravity. Part of the soot from Australia's fires, for example covered glaciers in New Zealand . But most of these Australian-born particles fell into the sea when the smoke had to cross the vast Pacific, said Neal Blair an environmental engineer at Northwestern University.

(How particles affect the sea.) The particles could potentially fertilize the oceans with nutrients in the smoke, like nitrogen, Blair noted.)

The most visible smoke then returns to the surface world from where it came from relatively quickly. However, the invisible components of smoke are a much larger and more influential story.

Invisible Smoke

When forests, forests, and grass burn, the vast majority burn the smoke that is created is invisible and odorless. Most of the burned wood – of the order of 90 percent – is burned to carbon dioxide, a strong greenhouse gas, Dubey explained from Los Alamos released into the atmosphere. From September 1, 2019 to January 15, 2020, according to Copernicus & # 39; Parrington, it was around 400 megatons of carbon dioxide. This corresponds to around 75 percent of the total carbon emissions that Australia currently emits into the atmosphere annually.

Much of this carbon dioxide will likely remain in the atmosphere and live there for hundreds of years. Plants on land and plankton in the ocean consume part of this carbon dioxide – but exactly how much is unknown.

"It will have climatic consequences," said Dubey.

Meanwhile, burned wood releases other types of invisible gases that lead to wheezing, lung irritation and breathing pain. When sunlight reacts with some of these invisible molecules like carbon monoxide, chemical ozone is created in the atmosphere. Ozone is difficult to breathe.

"It ignites the tissues of the lungs," said NCAR's Buchholz, adding that Melbourne had seen high concentrations of ozone.

  CO2 emissions from Australian forest fires.

CO2 emissions from Australian forest fires.

Image: Copernicus Atmosphere Monitoring Service / ECMWF

This ozone in combination with visible soot pollution (referred to above as particles) leads to some of the worst – and sometimes worst – air quality on Earth. "Now you have Syndey with worse air pollution than Delhi," said Dubey, referring to India's hideous air quality.

Winds will gradually wash away these harmful fumes, but not before the toxins have entered millions of Australian lungs.

Other invisible gases that are burned from Australian scrubland, such as carbon monoxide and related molecules, are thrown into the air like the visible particles. Here, says Dubey, carbon monoxide lives in the atmosphere for about three months before it is brought into its final form by naturally occurring chemical reactions – the heat-trapping greenhouse gas carbon dioxide.

"The atmosphere is often referred to as a huge chemical laboratory," said Parrington.

The Stratosphere

While most of the visible soot smoke lives and soon dies in the troposphere, a small portion of Australian smoke has been carried further into the troposphere. The next level of the atmosphere is the stratosphere, as Dubey noted (the most famous guitar in the world was named after this sublime region).

The stratosphere begins about 10 km in the atmosphere and as soon as particles rise there it can absorb it. It takes longer for it to fall to the surface – largely because there is no weather to wash it back down to earth.

"If [particulates] get there, they can survive a year," said Dubey.


And so goes the story of Australia and the world of smoking.

And so goes the story of Australia and the world of smoking.

It is terrible to breathe and reacts with sunlight to breathe even more terribly.

And in the coming decades, invisible smoke may be the most insidious of all air pollution: In a world in which carbon dioxide is already accumulating at historically and geologically unprecedented rates, unprecedented fires can also supply more and more heat-trapping gases to the Earth's atmosphere, which increases relentlessly warmed up.


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