I remember this from the early seventies when we were then trying to stave off the next ice age. The idea was you went to the Benguela Current pumped cold water up to the surface where it would warm up. However this was supposed to stop the world cooling down not stop the world heating up.

Frank Brookes, Taunton, UK

How much carbon is released into the atmosphere by production, deployment and maintenance of one such pipe?

Cees de Valk, Zwolle, the Netherlands

When hydrogen powered cars are discussed, scientists often point out that their emissions (water vapour) are worse than CO2 as a greenhouse gas - so how does encouraging more cloud (water vapour) formation prevent global warming ?

tony, birmingham, uk

First scientists tell us that research for the last 20 years shows the rate of global warming is increasing and in 20 or 30 years more it will be to late to do anything. Then Dr LeQuere scientists deride any plan to do something before its too late by saying we need 20 to 30 years of research first. Dr LeQuere is 100% certain so who does he work for?

The Sea Pipe idea is not new it is contained in Jerry Pournelle's "A Step Farther Out" (1981) a collection of interesting and alternative solutions. Jerry is not an idiot with no practical experience, he actually has "advanced degrees in psychology, statistics, engineering, and political science, including two PhDs....worked in operations research at Boeing, The Aerospace Corporation, and North American Rockwell Space Division...(with) Stefan T. Possony he wrote numerous publications including The Strategy of Technology,... textbook at US Miltiary Academy (West Point) and the US Air Force Academy (Wikipedia)" What has LeQuere done?

Nicholas Kulkarni, Kings Lynn, Norfolk

Conspiracy theorists who contend that the eco-scientists are simply self-seekers are, themselves, simply wishful thinkers. Lovelock has been working in this field for years and years;long before it was fashionable.
No genuine effort must be discounted. To simply rely on man's collective will and effort to reduce or nullify emissions is madness; we must seek other solutions without being lulled into a false sense of security that there is a quick fix.
That said, we still need major and deep cuts in emissions from the big producers to have any chance of regaining some balance in the atmosphere.

John Pownall, Bridport,

Would someone please explain the physics of 'Global warming'. I have an 'A' level in physics but cannot understand whether 'green house' gasses allow more radiation to reach the earth or prevent radiation from leaving the earth?
No explanation has been given the lay public.
I do know my walking barefoot or sorting rubbish will not save the planet.

Robert, London, UK

Maybe we could combine the iron enrichment idea with this one to get the best of both worlds.

Pass it to an engineer!!!

David, Dubai, UAE

Good.

Sally Saltash, Nottingham,

I am a student of Environmental Science at the University of Kansas and have noted a disconcerting trend for repetitive thinking. Reducing emissions and the usual batch of rhetoric are important goals, but unless more researchers are willing to tackle new ideas and approaches then this field will stagnate. I commend Lovelock and Rapley for their novel idea. I commend Lovelock and Rapley for their novel idea. BRAVO!

Joshua Burns, Leavenworth, Kansas

How cost effective would this be?
By how much is it supposed to reduce the global temperature, and over what period of time?
We haven't even had the figures for Kyoto yet.

Dave, Southampton, UK

It is crazy to talk about further interfering with nature - I think man is doing enough already. There is still great doubt about the magnitude that man is affecting the climate, and a number of scientists doubt that there is any affect at all. All that we do know is that the world is heating up, and that this heating is within the precedent of geological records. For those who say we have no time to waste, man has been modifying the climate for thousands of years - just consider the de-forestation of europe.

It seams that the only people 100% certain either way are those whose careers depend on global warming being an 'inconvenient truth', and those who are in the pay of oil companies.

Jeff Whiten, Cambridge,

I am skeptical about this idea for two reasons. First, it would only be a temporary fix as the Phytoplankton would eventually return to the surface through upwelling. These carbon rich phytoplankton would then release the carbon they are storing thereby putting us back to square one. Secondly, has anyone considered the possible adverse reactions having a massive Phytoplankton bloom would cause?

Caryn, Fairbanks, Ak