Researchers Hypothesize How To Best
Pollute Earth Via Geoengineering Strategies
A group of academics are considering engineering strategies
to pollute the earth in an effort to stabilize climate.
The Massachusetts Institute of Technology convened a symposium
here to discuss the potential benefits and pitfalls of geoengineering,
also called climate engineering. Everything from shooting light-blocking
particles into the atmosphere to "artificial
trees" is being seriously studied, despite trepidation
among researchers and opposition
During talks, academics said climate engineering techniques
are not well understood and, because of the complexity of the
global climate system, individual approaches are pockmarked with
Still, speakers at the event said it's time to step up research
in geoengineering to sort out which approaches are worth serious
consideration. But they cautioned against expecting easy fixes
or abandoning efforts to ratchet down the growth of greenhouse
gas emissions in the atmosphere.
"At this point the fear is that if we talk about this, people
will stop cutting emissions, which is a rational fear. But the
idea that we shouldn't have a research program would be a real
mistake," said David Keith, the director of the ISEEE Energy
and Environmental Systems Group at the University of Calgary during
his talk the symposium, which was called Engineering a Cooler
Speakers said each climate engineering approach needs to be viewed
with an associated cost and risk. For example, one relatively
inexpensive idea is to shoot particles, called aerosols, into
the air in order to block the amount of heat from the sun that
reaches the earth's surface.
The cooling effect from aerosols, such as sulfur dioxide, in
the atmosphere is rapid--measured in days or years. But they also
impact the planet's water cycle. Early models show that large-scale
efforts to inject aerosols in the atmosphere would likely make
certain areas drier and affect the monsoons in India and Asia,
said Joyce Penner, a professor of atmosopheric sciences at the
University of Michigan.
Even with the risks and uncertainties of climate engineering,
speakers said that there is risk with the so-called business-as-usual
scenario where the concentration of greenhouse emissions continues
to increase at its current pace.
These heat-trapping gases in the atmosphere are forecast to raise
average global temperatures, speakers said. But there are a number
of regional impacts from global warming, which will likely spur
more research in planet-level engineering, said Thomas Karl, the
director of NOAA's National Climatic Data Center.
For example, higher temperatures directly affect water and agriculture.
The productivity and ability to reproduce of common crops goes
down after certain temperature levels, Karl noted. Pests have
a longer time to populate and weeds grow better with more carbon
dioxide, too, he said. The west of the U.S. is already feeling
the impact of droughts, which will continue if mountain snowpack
"It's an important choice to make even if we don't do a
thing--that's a choice itself," said Karl. "The consequences
of not studying this are enormous--understanding the physical,
ecosystem, and societal impacts."
Engineering for a cooler planet
There are two general approaches to engineering for a cooler planet:
reflecting sunlight back into space or removing carbon dioxide
from the air and storing it.
Injecting sulfur-based aerosols in the atmosphere have a known
cooling effect observed in volcanic eruptions, including Mount
Pinatubo in 1991. The approach is more practical than, say, placing
mirrors in space. But there still isn't suitable understanding
of how the entire climate system would react, including potential
changes to ocean circulation, ocean ecosystems, and land precipitation,
Also, blocking sunlight from space does not address the problems
caused by higher concentrations of carbon dioxide on earth, notably
ocean acidification which makes it more difficult for marine animals
with shells or corals to grow, speakers noted.
Other approaches for reflecting heat back into space include spraying
sea salt from special-purpose boats to enhance the reflectivity
of clouds or installing white roofs on buildings to bounce more
sunlight back into space.
Land-based approaches to reducing greenhouse gas concentrations
include growing algae-based fuels at massive scale, storing carbon
dioxide in underground geological formations, and making charcoal
with plants to create a soil amendment called biochar.
There have also been 12 tests to stimulate plankton growth by
"fertilizing" the ocean with iron. The goal is to create
a rapid "plankton bloom" which will remove carbon dioxide
and sequester it in the ocean. But this technique is difficult
to verify and risks transforming the existing ocean ecosystems,
said Tim Lenton, professor of earth system science at the University
of East Anglia.
Because of the risk and uncertainly, Lenton said he is not convinced
that climate engineering proposals to block solar radiation makes
sense. On the other hand, land-based approaches create competition
with other uses of land, notably agriculture.
One area that clearly needs further research is the life-cycle
analysis of different climate engineering idea, Lenton said. For
example, dumping iron into the ocean to grow plankton has an associated
"You'll find out when you do the full calculation, it's
very difficult to make it carbon negative," he said. "Because
of the emissions in simply deploying the technology, it will veto
a number of options."
The computational models to simulate the regional impact of climate
changes need to be improved as well, said David Battisti, a professor
of atmospheric sciences at the University of Washington. In research
he presented on Friday, Battisti found that once models took into
account ice and ocean effects from aerosol injection, there was
a significant variation on the projected impact on temperatures
The symposium at MIT is not the first meeting of scientists to
consider geoengineering--the idea has been discussed for decades.
But some of the academics on Friday said the current trajectory
of climate change argues in favor of at least doing research on
climate engineering techniques, even if these projects are ultimately
There is also a uncertainty around climate policy and how effective
policies will be at cutting emissions, noted Keith. "It doesn't
mean that we have to do it. But it means that you do need to have
the capability to do it," he said.
In the near term, research in the field should be focused on
ranking different proposals, addressing both scientific and political
issues, said Philip Boyd, a professor of ocean biochemistry from
the University of Otago in New Zealand.
Boyd has created a model that ranks geoengineering schemes in
terms of efficacy, affordability, safety, speed of implementation,
and the ability to stop a project. Societal and political factors
need to be considered because conflicts over use of land, water,
and the ocean creates a "geopolitical mess."
"We pump up the potential for conflict," he said. "It's
just a minefield in terms of teasing these apart."
Reference Source: CNET.com
November 1, 2009