http://www.thestar.com/news/insight/2014/11/09/many_experts_say_technology_cant_fix_climate_change.html
Many experts say technology can't fix climate change
There are several geoengineering schemes for fixing climate change,
but so far none seems a sure bet.
*By:* Joseph Hall <http://www.thestar.com/authors.hall_joe.html> News
reporter, Published on Sun Nov 09 2014
As scientific proposals go, these might well be labelled pie in the sky.
Indeed, most of the atmosphere-altering techniques that have been
suggested to combat carbon-induced global warming are more science
fantasy than workable fixes, many climate experts say.
"I call them Rube Goldberg <http://www.rubegoldberg.com/>ideas," says
James Rodger Fleming, a meteorological historian at Maine's Colby
College, referring to the cartoonist who created designs for
gratuitously complex contraptions.
"I think it's a tragic comedy because these people are sincere, but
they're kind of deluded to think that there could be a simple, cheap,
technical fix for climate change," adds Fleming, author of the 2010 book
/Fixing the Sky: The Checkered History of Weather and Climate Control./
Yet the idea that geoengineering --- the use of technology to alter
planet-wide systems --- could curb global warming has persisted in a
world that seems incapable of addressing the root, carbon-spewing causes
of the problem.
And it emerged again earlier this month with a brief mention in a United
Nations report on the scope and imminent perils of a rapidly warming world.
That Intergovernmental Panel on Climate Change report
<http://www.ipcc.ch/>, which seemed to despair of an emissions-lowering
solution being achieved --- laid out in broad terms the types of
technical fixes currently being studied to help mitigate climate
catastrophe.
First among these proposed geoengineering solutions is solar radiation
management, or SRM, which would involve millions of tons of sulphur
dioxide (SO2) being pumped into the stratosphere every year to create
sun-blocking clouds high above the Earth's surface.
Anyone Canadian who remembers the unusually frigid summer of 1992,
caused by the volcanic eruption of Mount Pinatubo in the Philippines a
year earlier, grasps the cooling effects that tons of stratospheric SO2
can have on the planet.
And because such natural occurrences show the temperature-lowering
potential of the rotten-smelling substance, seeding the stratosphere
with it has gained the most currency among the geoengineering crowd.
One method put forward for getting the rotten-smelling stuff into the
stratosphere could well have been conceived by warped cartoonist Goldberg.
"You could make a tower up into the stratosphere, with a hose along the
side" says Alan Robock, a top meteorologist at New Jersey's Rutgers
University who has long studied SRM concepts.
The trouble is that any stratosphere-reaching tower built in the
tropics, where the SO2 would have to be injected for proper global
dispersal, would need to be at least 18 kilometres high.
Other stratospheric seeding suggestions include filling balloons with
the cheap and readily available gas --- it's routinely extracted from
petroleum products --- and popping them when they get up there.
But Robock says "the most obvious way to go" would be to fly airplanes
up and then spray SO2 into the stratosphere.
Once up there, the sulphur dioxide particles would react with water
molecules and form thin clouds of sulphuric acid droplets that could
encircle the Earth and reflect heating sunlight back into space.
Placing the cloud in the stratosphere is a must as the droplets last
about a year there while they fall within a week in the lower troposphere.
Still, the clouds, which would rain sulphuric acid back down on the
Earth's polar regions, would require frequent replenishment, with about
5 million tons of SO2 being needed each year to maintain their
reflective capacity, Robock says.
Due to uncertainties about the droplet sizes that would be produced by
SO2 cloud-seeding, no one is certain how much cooling the technique
would create.
"We don't know how thick a cloud we could actually make and how much
cooling there would be," Robock says.
Though he's devoted much of his career to studying sun-blocking
proposals, Robock is in no way convinced of their merits.
"I have a list of 26 reasons why I think this might be a bad idea," he says.
Chief among these is that the cooling produced by SRM would be uneven
around the globe, with the greatest temperature drops being seen in the
tropics.
"And so if you wanted to stop the ice sheets from melting . . . you'd
have to overcool the tropics."
The scheme would also produce droughts in heavily populated areas of the
world such as the Indian subcontinent, he says.
"Another thing on my list is unexpected consequences. I mean, we don't
know what the risks would be. We only know about one planet in the
entire universe that sustains intelligent life. Do we want to risk this
one planet on this technological fix?"
Though SRM thinking still centres on sulfates as the best cloud-seeding
compounds, some are now looking at manufactured nanoparticles to send
into the stratosphere, meteorological historian Fleming says.
"There's some talk about designer particles . . . but I don't know of
any production stream, and that would make it much more expensive."
The second major proposed geoengineering strategy to combat global
warming is based on carbon dioxide (CO2) removal.
This could take place either at large sources of CO2 such as power
plants or from the air itself, where even at today's climate-
threatening levels, it exists in low concentrations of about 400 parts
per million.
Know variously as carbon dioxide removal (CDR) or carbon capture and
sequestration (CCS), there are several strategies being discussed.
All the plans, however, would likely entail huge costs, the use of
dangerous chemicals and uncertain storage prospects, Fleming says.
"There are chemical means that would use some very alkaline, harsh
chemicals."
He notes that there are also thermodynamic means --- kind of the way
they make dry ice and they just suck it out and condense it (into a
liquid or solid)."
But thermodynamic removal and compression techniques, Fleming says, are
prohibitively expensive and require the use of large amounts of
carbon-producing energy.
This is largely due to the increased weight carbon acquires by combining
with oxygen during the burning process.
A ton of coal, for example, produces more than three tons of carbon
dioxide because of the added oxygen load, Fleming says.
"To make it really effective you'd have to have about a 30-per-cent
increase in world energy use. But it would have to come from renewable
(sources), which are not in the offing right now."
Other removal plans would employ membrane filters that are permeable to
all the air's component molecules except carbon.
"This seems viable on a small scale, but the question is, as in all
these projects: how do you make it a very large and very viable and
economically feasible?" Fleming says.
Most plans would see the captured CO2 turned back into a burnable fuel
by removing the oxygen component, or have it condensed into a liquid
form and pumped into underground caverns or ocean trenches.
But the fuel idea would also requite massive energy inputs to crack the
molecule into its two elements, and the storage scheme would likely
produce leakage.
Others are proposing to turn the captured carbon into charcoal by
burning it in oxygen-free fires and burying it underground for soil
enrichment.
"The problem with that one is the scale," Fleming says. "The topsoil of
the world is not large enough to capture all the carbon of industry."
Climate altering schemes go back to at least 1841, when pioneering U.S.
meteorologist James Pollard Espy
<http://www.encyclopedia.com/topic/James_Pollard_Espy.aspx> published a
rather ruinous proposal.
"He observed that oftentimes it rained after giant fires," Fleming says.
"So he thought, well, maybe we can stimulate artificial rains by
lighting the Appalachian forests all the way down the east coast of the
U.S. and then the westerly winds would bring the rains across the
eastern seaboard."
--
Alan Robock
Alan Robock, Distinguished Professor
Editor, Reviews of Geophysics
Director, Meteorology Undergraduate Program
Department of Environmental Sciences Phone: +1-848-932-5751
Rutgers University Fax: +1-732-932-8644
14 College Farm Road E-mail: [email protected]
New Brunswick, NJ 08901-8551 USA http://envsci.rutgers.edu/~robock
http://twitter.com/AlanRobock
Watch my 18 min TEDx talk at http://www.youtube.com/watch?v=qsrEk1oZ-54
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