"In principle this idea should work, and it should definitely be examined further," said John Latham, an atmospheric scientist at the University Corporation for Atmospheric Research in Boulder, who is also developing engineering solutions to mitigate climate change.
Preliminary laboratory tests using cylindrical pipes in a tank of water have shown that the concept has potential, at least on a small scale, Lovelock and Rapley point out.
Making the Problem Worse?
But there are a number of issues with such a proposal, other researchers say.
"Pumping deep water to the surface not only pumps nutrients up, but also carbon dioxide," said Penny Chisholm, an environmental engineer at the Massachusetts Institute of Technology in Cambridge.
Initially the deep waters might "exhale" carbon dioxide into atmosphere, adding to the global warming problem.
"Only after the outgassing is complete will the surface ocean start to take up carbon dioxide, and it is unclear whether there will actually be a net transfer of carbon dioxide to the deep ocean," said Eric Achterberg, an oceanographer at the University of Southampton in England.
Another concern is that meddling with oceanic water circulation might be damaging to ocean life.
"If done on a large enough scale then problems with oxygen depletion could occur in subsurface waters, which would probably have knock-on effects for ecosystems," said Toby Tyrrell, an ocean ecology expert at the University of Southampton.
Time to Test
Lovelock and Rapley acknowledge that there could be problems but still think that the idea deserves to be tested.
The problem of global warming is so serious, they say, that we may have to resort to climate-engineering solutions and accept some of the unwanted consequences.
"Even if we stopped emitting carbon dioxide tomorrow we are still committed to significant temperature rise," Rapley said.
"We don't think that scrubbing carbon dioxide out of chimneys and driving energy efficient cars will be sufficient. We need to draw carbon dioxide out of the atmosphere too."
The pair is already working with an anonymous sponsor on building an oceanic prototype.
"We can do a small-scale trial and discover any problems, giving us opportunity to back off if need be," Rapley said.
If all goes well the scientists envision situating their pipes in areas where they would have a dual purpose, such as the Gulf of Mexico and the Coral Sea off northeast Australia.
Cooler surface waters in such locations could help take the oomph out of Atlantic hurricanes and revitalize coral in the Great Barrier Reef.
The new proposal ties back to Lovelock's best-known work, the Gaia hypothesis.
In the 1960s Lovelock formulated the idea that Earth functions like a living organism, with both living and nonliving parts interacting to regulate the planet's environment. (Related: "New Technologies Emerge in Search for Alien Life" [February 7, 2003].)
Lovelock and Rapley see today's global warming as a disease of Earth caused by human actions.
"Our idea is to stimulate the Earth's immune system," Rapley said, "and help it to cure itself of its current infection."
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