Pipes hung in the sea could help planet to 'heal itself'

Pipes hanging in the ocean might bring global warming under control, two of Britain's most distinguished scientists suggest today.

By mixing deeper water with surface water, they could help the sea absorb vastly more carbon dioxide, the principal greenhouse gas, say James Lovelock – creator of the Gaia hypothesis which sees the earth as a single organism – and Chris Rapley, the director of the Science Museum in London.

In a letter published in the journal Nature, Professor Lovelock and Dr Rapley suggest that the ocean could be helped to take up much more carbon by "fertilising" the plankton in its top layer with nutrient-rich waters from deeper down, that could be pumped upwards through pipes by the action of the waves.

The idea is to provide a planetary-scale techno-fix for climate change of gigantic proportions, yet remarkable simplicity. Far-fetched as it may seem to some, the Virgin boss Sir Richard Branson, who in February launched a $25m (£13m) prize for the best way of removing carbon dioxide from the atmosphere, is considering funding a trial of the project.

Although a gigantic piece of geo-engineering – many thousands, if not millions, of pipes would be needed to act on a whole-earth scale – it would, in essence, be uncomplicated and use no energy other than the natural power of the ocean, say the scientists.

But most important of all, it will "help the earth to help itself" by making use of the carbon cycle, the natural process by which carbon is transferred from vegetation on land, to the atmosphere and to the ocean, where much of it is sequestered, or locked up. The idea follows directly from Professor Lovelock's celebrated theory, now widely accepted, that the earth possesses a planetary-scale control system that, for millions of years, has kept the environment fit for life (and which he christened Gaia).

He believes (and Dr Rapley, the former head of the British Antarctic Survey, agrees) that global warming is destabilising the system and making it work against us, with a whole series of positive feedbacks that will boost the warming even further. Both men feel that climate change is proceeding so fast – as shown in the increasingly rapid melting of the ice in the Arctic Ocean – that the conventional approaches the world has been discussing for the past 15 years, such as stopping the burning of fossil fuels, will simply not now be enough. Only by using the earth's own processes might we have a hope of getting climate change under control.

"We can't cure the planet, we haven't the power, but we just might be able to make it go into reverse phase and cure itself," Professor Lovelock announced yesterday.

In their letter, the two scientists focus on the fact that the surface layer of the ocean, where algae and other plankton live, is increasingly starved of the nutrients such as phosphates and nitrates which help them grow. The nutrients exist in colder water lower down but as the surface water warms, it is allowing less mixing with the nutrient-rich layers beneath.

They suggest using free-floating or tethered vertical pipes, perhaps 100 to 200 metres long, 10 metres in diameter and with a one-way flap valve at the lower end for pumping by wave movement, to increase the mixing. That would fertilise algae and encourage them to bloom, taking up much more CO2, which is eventually locked up in the tiny shells of plankton when they die and fall to the ocean bottom.

They believe it would have an added benefit of producing the chemical dimethyl sulphide, which eventually breaks down into other compounds that help clouds to form, which in turn reflect back more of the sun's radiation.

"Such an approach may fail, perhaps on engineering or economic grounds," they say. "And the impact on ocean acidification will need to be taken into account. But the stakes are so high that we put forward the general concept of using the earth system's own energy for amelioration.

"The removal of 500 gigatonnes of carbon dioxide from the air by human endeavour is beyond our current technological capability. If we can't 'heal the planet' directly, we may be able to help the planet heal itself."

A company in the United States, Atmocean, is already trying out its own version of the system, quite independently of the suggestion from Lovelock and Rapley. A spokesman for Sir Richard Branson said last night: "Richard has been in touch with Jim Lovelock about this idea and is very interested. We are looking into it to see if we can fund a trial."