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[school-discuss] a way for humans to control global warming without a behavior change ?

  Media Alerts Stories Archive ---> 

August 20, 2002


LIVERMORE, Calif. ? Researchers from the Lawrence Livermore National 
Laboratory have determined that the depth of an injection of carbon dioxide 
into the deep ocean is a good predictor of how effective that location is at 
sequestering carbon away from the atmosphere.

Direct injection of CO2 into the deep ocean has been proposed as a way to slow 
the accumulation of carbon dioxide in the atmosphere, one of the causes of 
global warming. In the direct injection scenario, fossil-fuel carbon dioxide 
is injected into the ocean interior, bypassing the mixing processes that 
would otherwise cause a relatively slow transfer of excess atmospheric CO2 in 
to the deep ocean.

In a study released today in Geophysical Research Letters, Ken Caldeira and 
Philip Duffy of the Climate and Carbon Cycle Modeling Group and Michael 
Wickett of the Center for Applied Scientific Computing, all at Livermore, 
show that the depth, rather than radiocarbon, is a relatively good predictor 
of the effectiveness of CO2 injection.

The researchers studied both radiocarbon dating (typically used to date 
anthropologic items) and the depths of injection to determine the 
effectiveness of direct CO2 injection as a carbon sequestration strategy.

Scientists used one-dimensional box-diffusion models and three-dimensional 
simulations run under the radiocarbon and sequestration scenarios described 
in Livermore's Ocean Carbon-cycle Model Intercomparison Project protocols.

"These simulations indicate that the amount of time it takes for a water 
parcel to return to the ocean surface increases with depth, but is not 
related to the amount of time since that parcel was last at the surface," 
Duffy said.

Injections were simulated at 800 meters, 1500 meters and 3000 meters for 100 
years near the Bay of Biscay, New York City, Rio de Janeiro, San Francisco, 
Tokyo, Jakarta and Bombay.

The models showed that injection at 3000 meters is quite effective at 
sequestering carbon from the atmosphere for several centuries while 
injections at shallower depths are less effective. In general, injections 
into the Pacific Ocean (San Francisco and Tokyo) were more effective than 
injection at the same depth in the Atlantic Ocean (New York City, Rio de 
Janeiro and the Bay of Biscay).