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Geoengineering Trails Get
Underway
Volcanic ash inspires sunshade
FIELD trials for experiments to engineer the climate have begun. Next
month a team of UK researchers will hoist one end of a 1-kilometre-long
hose aloft using a balloon, then attempt to pump water up it and spray it
into the atmosphere:
The water will not affect the climate. Rather, the experiment is a proof of
principle to show that we can pump large quantities of material to great
heights. If it succeeds, a larger-scale version could one day pump sulphate
aerosols into the stratosphere, creating a sunshade that will offset the
greenhouse effect.
The trial, led by Matthew Watson of the University of Bristol, UK, is part of
a £2 million project called Stratospheric Particle Injection for Climat
Engineering (SPICE). Funded by two UK research councils, it also aims to
find out the ideal particles to use in an atmospheric sunshade and will
attempt to model their effects in greater detail than ever before. The test
is not alone: a string of other technologies that could be used to
"geoengineer" our environment are being field-tested (see "Coping with
emissions").
In his blog, The Reluctant Geoengineer, Watson argues that we need to
investigate the effects of sulphate aerosols as a last-resort remedy should
the climate start to change rapidly. Researchers contacted by New
Scientist agreed with Watson that such research should continue, if only
to find out whether the techniques are feasible. "I'd say there's a 50-50
chance we'll end up doing it, because it'll get too warm and people will
demand the planet be cooled off," says Wallace Broecker of Columbia
University in New York. But there was less enthusiasm for SPICE's approach
to the problem.
There are "large gaps" in our understanding of geoengineering, says
Thomas Stocker of the University of Bern in Switzerland. Stocker helped to
organise an expert meeting on geoengineering in June for the
Intergovernmental Panel on Climate Change. It identified key unanswered
questions that should be a focus for research. However, it is not clear that
field trials like Watson's will provide the answers.
One area of doubt over injecting aerosols into the stratosphere is whether
it will change the behaviour of high-altitude clouds. That could in turn
affect the climate in ways beyond what was intended - and for now, we
don't know how, or how much. Aerosols could also deplete the ozone layer,
contribute to air pollution and may alter visibility in the same way as large
volcanic eruptions can.
The SPICE test won't answer any of these questions, says David Keith of
Harvard University. "I think it's a little reckless." The most interesting result
will be how the public reacts, he says.
What's more, Keith adds, in the long run delivering sulphates to the
stratosphere with a hose would be a bad idea. Spraying aerosols locally
allows the particles to clump together, making them less effective at
reflecting sunlight and more likely to be swept down by rain (Environmental
Research Letters, DOI: 10.1088/1748-9326/4/4/045108).
Keith's own studies suggest that if we were ever forced to try to screen
out some of the sun's rays globally, it would be more effective to spray
sulphuric acid from aircraft (Geophysical Research Letters, DOI:
10.1029/2010GL043975).
It would also be cheaper, costing a few billion dollars a year according to a
study by Aurora Flight Sciences, an aeronautical firm in Cambridge,
Massachusetts. Such figures are tiny compared to the trillions that the
consequences of climate change could cost the global economy if
emissions continue to rise at current rates.
The point, says Ken Caldeira of the Carnegie Institution for Science in
Stanford, California, is that experiments like Watson's, which test relatively
simple delivery systems, address the issue of cost. But, since the Aurora
study has shown that cost is not a critical factor - a sunshade will be
relatively inexpensive - the critical questions relate to potential risks.
More importantly, since a stratospheric sunshade is intended to have a
global impact, all countries must agree to such a project and to its precise
extent, which is unlikely to happen.
One possibility that may help countries agree is that the sunshade need
not be applied evenly across the globe. Caldeira has created, in a climate
model, a sunshade with much larger quantities of aerosols above the poles
than above the tropics. This produced a temperature distribution much
closer to the pre-industrial climate than could be achieved with a uniform
sunshade (Environmental Research Letters, DOI: 10.1088/1748-932
/5/3/034009).
Caldeira and others are now toying with the idea of regional
geoengineering, or "geoadaptation". Some techniques, such as making
clouds over the seas more reflective, should have localised effects, so
countries could in theory tinker only with their own climate.
But here too uncertainties need to be resolved. Gavin Schmidt of the NASA
Goddard Institute for Space Studies in New York points out that changes in
one area will have a knock-on effect on the other side of the planet.
"What happens in Vegas does not stay in Vegas," he says. We could
perhaps predict these long-range effects, but we cannot eliminatethem.
Schmidt says that what we need is not field tests, but better modelling
studies. Most simulations of geoengineering are "naive", he says, and
cannot model all the possible side effects. "People are not doing the right
kinds of experiments to assess these effects," he says.
Additional reporting by Catherine Brahic
Coping with emissions
THE pipe-to-the-sky experiment is not the only geoengineering method
that is being tested.
In 2009, a team of Russian scientists sprayed a small amount of sulphate
aerosols into the atmosphere and found that they blocked between 1 and
10 per cent of incoming solar radiation (Russian Meteorology and
Hydrology, DOI: 10.3103/S106837390905001X).
Iceland is testing a less contentious technique to deal with our carbon
emissions: turning them into rock. The CarbFix project aims to capture
carbon dioxide from a local geothermal power plant, dissolve it in water and
inject it into basalt rock, where it will react with magnesium, calcium and
iron to form carbonates. If it works, the CO2 should stay put even in an
earthquake. It is the safest way of storing CO2, according to project
leader Sigurður Reynir Gíslason of the University of Iceland in Reykjavik.
The team plans to start the gas injections later this month.
Adding iron to the ocean can trigger plankton blooms that suck up CO2,
but a 2009 field test gave mixed results. That's because the test site was
unsuitable, says Richard Lampitt of the National Oceanography Centre in
Southampton, UK. He and colleagues hope to repeat the trial.
Elsewhere, Ken Caldeira of the Carnegie Institution for Science in Stanford,
California, has permission to add sodium hydroxide - an alkali - to a small
patch of ocean to see if it can reverse the effects of ocean acidification.
Finally, California-based engineer Armand Neukermans is building a nozzle
that will spray seawater into clouds, making them whiter and better able to
reflect sunlight into space.
Geoengineering trials get under way - environment - 09 September 2011 - New Scientist
Geoengineering Trails Get
Underway
Volcanic ash inspires sunshade
FIELD trials for experiments to engineer the climate have begun. Next
month a team of UK researchers will hoist one end of a 1-kilometre-long
hose aloft using a balloon, then attempt to pump water up it and spray it
into the atmosphere:
The water will not affect the climate. Rather, the experiment is a proof of
principle to show that we can pump large quantities of material to great
heights. If it succeeds, a larger-scale version could one day pump sulphate
aerosols into the stratosphere, creating a sunshade that will offset the
greenhouse effect.
The trial, led by Matthew Watson of the University of Bristol, UK, is part of
a £2 million project called Stratospheric Particle Injection for Climat
Engineering (SPICE). Funded by two UK research councils, it also aims to
find out the ideal particles to use in an atmospheric sunshade and will
attempt to model their effects in greater detail than ever before. The test
is not alone: a string of other technologies that could be used to
"geoengineer" our environment are being field-tested (see "Coping with
emissions").
In his blog, The Reluctant Geoengineer, Watson argues that we need to
investigate the effects of sulphate aerosols as a last-resort remedy should
the climate start to change rapidly. Researchers contacted by New
Scientist agreed with Watson that such research should continue, if only
to find out whether the techniques are feasible. "I'd say there's a 50-50
chance we'll end up doing it, because it'll get too warm and people will
demand the planet be cooled off," says Wallace Broecker of Columbia
University in New York. But there was less enthusiasm for SPICE's approach
to the problem.
There are "large gaps" in our understanding of geoengineering, says
Thomas Stocker of the University of Bern in Switzerland. Stocker helped to
organise an expert meeting on geoengineering in June for the
Intergovernmental Panel on Climate Change. It identified key unanswered
questions that should be a focus for research. However, it is not clear that
field trials like Watson's will provide the answers.
One area of doubt over injecting aerosols into the stratosphere is whether
it will change the behaviour of high-altitude clouds. That could in turn
affect the climate in ways beyond what was intended - and for now, we
don't know how, or how much. Aerosols could also deplete the ozone layer,
contribute to air pollution and may alter visibility in the same way as large
volcanic eruptions can.
The SPICE test won't answer any of these questions, says David Keith of
Harvard University. "I think it's a little reckless." The most interesting result
will be how the public reacts, he says.
What's more, Keith adds, in the long run delivering sulphates to the
stratosphere with a hose would be a bad idea. Spraying aerosols locally
allows the particles to clump together, making them less effective at
reflecting sunlight and more likely to be swept down by rain (Environmental
Research Letters, DOI: 10.1088/1748-9326/4/4/045108).
Keith's own studies suggest that if we were ever forced to try to screen
out some of the sun's rays globally, it would be more effective to spray
sulphuric acid from aircraft (Geophysical Research Letters, DOI:
10.1029/2010GL043975).
It would also be cheaper, costing a few billion dollars a year according to a
study by Aurora Flight Sciences, an aeronautical firm in Cambridge,
Massachusetts. Such figures are tiny compared to the trillions that the
consequences of climate change could cost the global economy if
emissions continue to rise at current rates.
The point, says Ken Caldeira of the Carnegie Institution for Science in
Stanford, California, is that experiments like Watson's, which test relatively
simple delivery systems, address the issue of cost. But, since the Aurora
study has shown that cost is not a critical factor - a sunshade will be
relatively inexpensive - the critical questions relate to potential risks.
More importantly, since a stratospheric sunshade is intended to have a
global impact, all countries must agree to such a project and to its precise
extent, which is unlikely to happen.
One possibility that may help countries agree is that the sunshade need
not be applied evenly across the globe. Caldeira has created, in a climate
model, a sunshade with much larger quantities of aerosols above the poles
than above the tropics. This produced a temperature distribution much
closer to the pre-industrial climate than could be achieved with a uniform
sunshade (Environmental Research Letters, DOI: 10.1088/1748-932
/5/3/034009).
Caldeira and others are now toying with the idea of regional
geoengineering, or "geoadaptation". Some techniques, such as making
clouds over the seas more reflective, should have localised effects, so
countries could in theory tinker only with their own climate.
But here too uncertainties need to be resolved. Gavin Schmidt of the NASA
Goddard Institute for Space Studies in New York points out that changes in
one area will have a knock-on effect on the other side of the planet.
"What happens in Vegas does not stay in Vegas," he says. We could
perhaps predict these long-range effects, but we cannot eliminatethem.
Schmidt says that what we need is not field tests, but better modelling
studies. Most simulations of geoengineering are "naive", he says, and
cannot model all the possible side effects. "People are not doing the right
kinds of experiments to assess these effects," he says.
Additional reporting by Catherine Brahic
Coping with emissions
THE pipe-to-the-sky experiment is not the only geoengineering method
that is being tested.
In 2009, a team of Russian scientists sprayed a small amount of sulphate
aerosols into the atmosphere and found that they blocked between 1 and
10 per cent of incoming solar radiation (Russian Meteorology and
Hydrology, DOI: 10.3103/S106837390905001X).
Iceland is testing a less contentious technique to deal with our carbon
emissions: turning them into rock. The CarbFix project aims to capture
carbon dioxide from a local geothermal power plant, dissolve it in water and
inject it into basalt rock, where it will react with magnesium, calcium and
iron to form carbonates. If it works, the CO2 should stay put even in an
earthquake. It is the safest way of storing CO2, according to project
leader Sigurður Reynir Gíslason of the University of Iceland in Reykjavik.
The team plans to start the gas injections later this month.
Adding iron to the ocean can trigger plankton blooms that suck up CO2,
but a 2009 field test gave mixed results. That's because the test site was
unsuitable, says Richard Lampitt of the National Oceanography Centre in
Southampton, UK. He and colleagues hope to repeat the trial.
Elsewhere, Ken Caldeira of the Carnegie Institution for Science in Stanford,
California, has permission to add sodium hydroxide - an alkali - to a small
patch of ocean to see if it can reverse the effects of ocean acidification.
Finally, California-based engineer Armand Neukermans is building a nozzle
that will spray seawater into clouds, making them whiter and better able to
reflect sunlight into space.
Geoengineering trials get under way - environment - 09 September 2011 - New Scientist
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