Two of Britain’s leading environmental thinkers say it is time to develop a quick technical fix for climate change.
Writing in the journal Nature, Science Museum head Chris Rapley and Gaia theorist James Lovelock suggest looking at boosting ocean take-up of CO2.
Their idea, already being investigated by a US firm, involves huge flotillas of vertical pipes in the tropical seas.
The two scientists say they doubt that existing plans for curbing carbon emissions can work quickly enough.
“We are taking the very strong line that we are not going to save the planet by the regular approaches like the Kyoto Protocol or renewable energy,” Professor Lovelock told BBC News.
“What we have to do is to look at it in a systems sense, or a Gaian sense, and see if it’s curable by direct action.”
Professor Rapley, who has just moved to head up the Science Museum from a similar post at the British Antarctic survey, said the two men developed the ocean pipes concept during country walks in James Lovelock’s beloved Devon.
Unbeknown to them, a US company, Atmocean, had already begun trials of a very similar technology.
Floating pipes reaching down from the top of the ocean into colder water below move up and down with the swell.
As the pipe moves down, cold water flows up and out onto the ocean surface. A simple valve blocks any downward flow when the pipe is moving upwards.
See how the pumps would work
Colder water is more “productive” – it contains more life, and so in principle can absorb more carbon.
One of the life-forms that might benefit, Atmocean believes, is the salp, a tiny tube which excretes carbon in its solid faecal pellets, which descend to the ocean floor, perhaps storing the carbon away for millennia.
Atmocean CEO Phil Kithil has calculated that deploying about 134 million pipes could potentially sequester about one-third of the carbon dioxide produced by human activities each year. But he acknowledges that research is in the early stages.
“There is much yet to be learned,” he told BBC News. “We need not only to move towards the final design and size (of the pipes), but also to characterise the ecological effects.
“The problem we would be most concerned about would be acidification. We’re bringing up higher levels of CO2 along with the nutrients, so it all has to be analysed as to the net carbon balance and the net carbon flux.”
Atmocean deployed experimental tubes earlier this year and gathered engineering data. The pipes brought cold water to the surface from a depth of 200m, but no research has yet been done on whether this approach has any net impact on greenhouse gas levels.
The company says a further advantage of cooling surface waters in regions such as the Gulf of Mexico could be a reduction in the number of hurricanes, which need warm water in order to form.
And Professors Lovelock and Rapley suggest that the ocean pipes could also stimulate growth of algae that produce dimethyl sulphide (DMS), a chemical which helps clouds form above the ocean, reflecting sunlight away from the Earth’s surface and bringing a further cooling.
In recent years, scientists have developed a wide range of technical “geo-engineering” ideas for curbing global warming.
Seeding the ocean with iron filings to stimulate plankton growth, putting sunshades in space, and firing sulphate aerosols into the atmosphere from a giant cannon have all been proposed; the iron filings idea has been extensively tested.
But the whole idea of pursuing these “technical fixes” is controversial.