Poster's note: I'm interested in the implications for geoengineering, and
I'd be keen to hear from list members. Could this be a negative feedback,
or a usable technique?

By Aristos Georgiou On 1/14/20 at 6:19 AM EST
Smoke from the devastating bushfires in Australia is expected to complete a
full circuit around the world, arriving back in the skies over the country
where it was produced, according to NASA. It has also traveled so high it
has reached the stratosphere—the second major layer of Earth's atmosphere.

The smoke had reached South America by January 8, turning skies hazy in
some regions, causing colorful sunrises and sunsets, the space agency said.

Since September last year, hundreds of fires have burned millions of
hectares in Australia, leaving at least 28 people dead, destroying around
2,000 homes and killing more than one billion animals, the BBC reported.

Scientists say that record-breaking hot and dry conditions are creating the
perfect environment for the fires to spread. These kinds of conditions are
likely to become more common in Australia as the world's climate changes,
Stefan Rahmstorf, from Germany's Potsdam Institute for Climate Impact
Research, told Time.

According to NASA, the heat and dryness has also led to the formation of
"an unusually large number" of so-called pyrocumulonimbus (pyrCbs) events.
These are thunderstorms that are generated by the fires themselves.

"They are triggered by the uplift of ash, smoke, and burning material via
super-heated updrafts. As these materials cool, clouds are formed that
behave like traditional thunderstorms but without the accompanying
precipitation," a NASA statement read.

While the formation of pyrocumulonimbus clouds is relatively common,
meteorologist Michael Fromm and colleagues from the U.S. Naval Research
Laboratory have detected more than 20 fire-induced storms in the last week
of December 2019 and the first week of 2020.

"By our measures, this is the most extreme pyrocumulonimbus storm outbreak
in Australia," Fromm said in a statement.

PyrCbs can help the smoke to spread around the world, by enabling it reach
the stratosphere, which begins at around 6.2 miles in altitude (above the
equator.) Some of the smoke pushed into the stratosphere by pyroCbs events
above Australia has reached altitudes of between 9 and 12 miles.

Australia fires ISS
The photograph below from the International Space Station shows extreme
fire activity on January 4, 2020.
"It is premature to compare and rank the height of this plume with others
because smoke plumes like this rise in altitude over the course of weeks,"
said Fromm.

"That said, preliminary evidence indicates that the current Australian
event will probably fall within the top five of all the plumes ever
documented in terms of height. And the overall volume of smoke injected
into the stratosphere appears to be among the largest observed in recent

Once the smoke is in the stratosphere, it can remain there for several
months, travelling thousands of miles from its source and affecting
atmospheric conditions globally.

New Zealand—which lies more than 1,000 miles away from Australia's east
coast—is being particularly badly affected by the fire smoke. The country
has experienced poor air quality in some areas and visibly darkened snow
has been spotted on mountaintops, according to NASA.

More locally, several Australian cities such as Sydney, Melbourne, Canberra
and Adelaide, have experienced dangerous air quality levels recently as a
result of the smoke, with more than 100 fires still burning in the east of
the country, the BBC reported.

Many of these fires are yet to be controlled. However, firefighters
announced Monday that they had finally brought Australia's largest
"megablaze" under control in what was a rare piece of good news this fire

The Gospers Mountain fire had burnt more than 800,000 hectares northwest of
Sydney over a three-month period. But firefighters in the state of New
South Wales said that "containment prognosis looks promising," with
much-needed wet weather forecast for the area in the next few days, AFP

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