New plane can show
geoengineering works
Tim Radford
With new aircraft, humans could potentially mimic volcanic action, dim the sunlight
and slow global warming, showing that geoengineering works. It’s a controversial
idea.
N
obody knows for sure whether we
shall ever see if geoengineering
works. But now somebody knows how
to do it.
Engineers have designed an aircraft that
could lift a cargo of sulphur dioxide to an
altitude of 20 kilometres and spray it into
the stratosphere to darken the skies, dim
the sunlight and damp down climate change
driven by emissions from factory chimneys,
power stations and vehicle exhausts.
The aircraft – already dubbed SAIL, or the
stratospheric aerosol injection lofter, could
cost no more than $2.35 billion a year for
airframe and engine, and the first eight could
be rolling down the runway 15 years from
now to begin flying 4,000 missions a year.
By the end of another 15 years, a fleet of
100 high-flying sulphate dumpsters could
be in business, making 60,000 high altitude
deliveries a year to combat global warming.
US scientists report in the journal
Environmental Research Letters that they
addressed the costs and practicalities of what
is certainly the most-frequently invoked and
hotly disputed form of climate engineering on
a global scale.
Possible catastrophe
It is considered necessary because, if humans
go on burning fossil fuels at the present
rates, greenhouse gas build-up in the
atmosphere could increase planetary average
temperatures to a catastrophic 3°C or more by
2100.
AgriKultuur |AgriCulture
Darkened skies do lower planetary
temperatures: violent volcanic eruptions have
in recent history injected cubic kilometres of
fine ash, smoke and sulphur into the upper
atmosphere on scales that lower global
average temperatures measurably.
For more than a decade, researchers have
argued that – since humankind collectively still
shows no great sign of drastically reducing
greenhouse gas emissions – some radical
form of solar geoengineering might be
necessary. Others have opposed the case,
citing possible unwelcome consequences.
But the first question was: could it be done
at all? The latest answer is that it can, but not
with existing hardware.
“This plan is a distraction that may well
encourage weaker action on emissions
reduction by governments in the hope they
will no longer be necessary”
“While we don’t make any judgment about
the desirability of SAI, we do show that
a hypothetical deployment programme,
starting 15 years from now, while both highly
uncertain and ambitious, would be technically
possible from an engineering perspective,”
said Gernot Wagner, of Harvard University.
“It would also be remarkably inexpensive, at
an average of around $2 bn to $2.5 bn per
year over the first 15 years.”
His co-author Wake Smith, who moved
from the aviation business to lecture at Yale
College, and who led the study, said he had
become intrigued by research that suggested
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