http://m.smh.com.au/environment/tim-flannerys-message-of-hope-new-third-way-technologies-will-help-combat-climate-change-20150812-gixwuk.html

Extract

... these geoengineering options are untested, and could have dangerous
side effects. Flannery says they are tantamount to "using poison to fight a
poison".

Flannery says the third way alternatives he has identified are very
different from radical geoengineering proposals because they "recreate,
enhance or restore" the processes that created a balance of greenhouse
gasses prior to human interference. "They do not seek to fight one poison
[excess carbon] with another [for example sulphur]," he writes. "Instead
they look to restore or learn from processes that are as old as life
itself. The third way is in large part about creating our future out of
thin air." This encompasses proposals and experiments that mostly draw CO₂
out of the air and sea at a faster rate than occurs presently, and to store
it safely. "It's what plants and a fair few rocks do."

Some third way alternatives are already quite well-known, such as
large-scale reafforestation and the addition of biochar to the soil.
Biochar is a type of charcoal produced from the slow, oxygen-free burning
of organic material. Creating biochar stores carbon for long periods and
can be added to soil and improve soil quality. But Flannery sees even
greater potential in less familiar methods to draw carbon from the
atmosphere including large-scale seaweed farming, the manufacture of
carbon-negative cement and new techniques for making plastic that draws CO₂
from the air. He canvasses strategies to absorb CO₂ by the "enhanced
weathering" of silicate rocks and even making "CO₂ snow" in the Antarctic
that could be stored in ice pits. Scientists are also investigating how the
earth's albedo, or reflectiveness, could help cool the planet. By painting
infrastructure white, cities might offset some of the warming they are now
experiencing.

In Flannery's assessment third way strategies could together be pulling
about four gigatonnes of carbon out of the atmosphere a year by 2050, about
40 per cent of current emissions. "These are the technologies we need to be
focussing on, that will give us a future," he says. But these innovations
will only be effective if major investments are made in developing them
now. "It's a bit like solar," Flannery says. "For the last 30 years solar
PV has been reducing its cost by about 10 per cent per annum but for 25 of
those 30 years it was still outrageously expensive and wasn't really
competitive … Many of these third way technologies are the same – we need
to start investing in them now to make sure we have the tools there in
future when we really need them, in 2030 or 2040 as the climate crisis
deepens. Then we will be really searching for ways to deal with this and
the only way we'll have the tools is if we start investing now."

Flannery has become a favourite target of climate change sceptics who
accuse him of exaggerating the threat of global warming and of
"quasi-religious" activism. He was the chief commissioner of the Climate
Commission, a body established by the Gillard government to provide
information on climate change before it was disbanded by the Abbott
government. He's now a member of the Climate Council, which is independent
and funded by the community.

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