Earth-cooling schemes

Earth-cooling schemes need global sign-off, researchers say



World's most vulnerable people need protection from huge and unintended impacts of radical geo-engineering projects.



Grimsvotn volcano
erupts in Iceland in 2011. Solar radiation management schemes spray
particles into the atmosphere to simulate cooling effects of volcanic
eruptions. Photograph: Egill Adalsteinsson/EPA




Controversial geoengineering
projects that may be used to cool the planet must be approved by world
governments to reduce the danger of catastrophic accidents, British
scientists said.
Met Office researchers have called for global
oversight of the radical schemes after studies showed they could have
huge and unintended impacts on some of the world's most vulnerable
people.
The dangers arose in projects that cooled the planet
unevenly. In some cases these caused devastating droughts across Africa;
in others they increased rainfall in the region but left huge areas of
Brazil parched.
"The massive complexities associated with
geoengineering, and the potential for winners and losers, means that
some form of global governance is essential," said Jim Haywood at the Met Office's Hadley Centre in Exeter.
The
warning builds on work by scientists and engineers to agree a
regulatory framework that would ban full-scale geoengineering projects,
at least temporarily, but allow smaller research projects to go ahead.
Geoengineering
comes in many flavours, but among the more plausible are "solar
radiation management" (SRM) schemes that would spray huge amounts of
sun-reflecting particles high into the atmosphere to simulate the
cooling effects of volcanic eruptions.
Volcanoes can blast
millions of tonnes of sulphate particles into the stratosphere, where
they stay aloft for years and cool the planet by reflecting some of the
sun's energy back out to space.
In 2009, a Royal Society report
warned that geoengineering was not an alternative to cutting greenhouse
gas emissions, but conceded the technology might be needed in the event
of a climate emergency.
Writing in the journal Nature Climate Change,
Haywood and others show that moves to cool the climate by spraying
sulphate particles into the atmosphere could go spectacularly wrong.
They began by looking at the unexpected impacts of volcanic eruptions.
In
1912 and 1982, eruptions first at Katmai in Alaska and then at El
Chichón in Mexico blasted millions of tonnes of sulphate into northern
skies. These eruptions preceded major droughts in the Sahel region of
Africa. When the scientists recreated the eruptions in climate models,
rainfall across the Sahel all but stopped as moisture-carrying air
currents were pushed south.
Having established a link between
volcanic eruptions in the northern hemisphere and droughts in Africa,
the scientists returned to their climate models to simulate SRM
projects.
The scientists took a typical project that would inject
5m tonnes of sulphate into the stratosphere every year from 2020 to
2070. That amount of sulphate injected into the northern hemisphere
caused severe droughts in Niger, Mali, Burkina Faso, Senegal, Chad and
Sudan, and an almost total loss of vegetation.
The same project
had radically different consequences if run from the southern
hemisphere. Rather than drying the Sahel, cooling the southern
hemisphere brought rains to the Sahel and re-greened the region. But
Africa's benefit came at the cost of slashing rainfall in north-eastern
Brazil.
The unintended consequences of SRM projects would probably
be felt much farther afield. "We have only scratched the surface in
looking at the Sahel. If hurricane frequencies changed, that could have
an impact on the US," said Haywood.
Matthew Watson, who leads the Spice project at Bristol University, said the study revealed the "dramatic consequences" of uninformed geoengineering.
"This
paper tells us there are consequences for our actions whatever we do.
There is no get-out-of-jail-free card," he told the Guardian.
"Whatever
we do is a compromise, and that compromise means there will be winners
and losers. That opens massive ethical questions: who gets to decide how
we even determine what is a good outcome for different people?
"How
do you get a consensus with seven billion-plus stakeholders? If there
was a decision to do geoengineering tomorrow, it would be done by white
western men, and that isn't good," Watson said.


Source:-
http://www.guardian.co.uk/environment/2013/mar/31/earth-cooling-schemes-global-signoff