Pipe dreams?

I noticed in my Nature alert today a short letter from James Lovelock and Chris Rapley about a potential mechanism for secreting atmospheric CO₂ in the seas. The plan described is to have large pipes (and they mean large - 100-200 m in length and 10 m in diameter!) floating in the sea vertically, allowing mixing of seawater above and below the thermocline. Phytoplankton (algae) require three main things in order to grow, light, nutrients and CO₂. The thermocline is a divide between the sun warmed surface water, which has sufficient light and CO₂ for growth, but few nutrients, and the cool, deeper water which is obviously too dark, but full of nutrients that have fallen out of the surface layers. There are natural places where the two waters mix called upwellings - here you get blooms of phytoplankton which use up CO₂ as they photosynthesise. The pipes would simulate these upwellings and stimulate the uptake of CO₂ by the phytoplankton. Phytoplankton also produce dimethyl sulphide (DMS - the characteristic "smell of the sea") which can stimulate the formation of clouds - cooling the planet by preventing the suns rays reaching the surface. The story has also been picked up by the BBC here (and the New Scientist and umpteen other places - Nature is quite good at getting its stories published elsewhere before they have themselves! My girlfriend used to tell me all the latest research news from the fee paper Metro before I'd even received the original articles) and has some nice diagrams of the pipes in action.

Atmocean, a US company have been developing such a system themselves and have a suitably dramatic video on youtube (note the use of Clubbed to Death by Rob D, as heard on the soundtrack of The Matrix - it signifies 'bad stuff happening').



It is great that someone is proposing some direct action with some science behind it. The idea is an interesting one, but probably won't work. Bold statement huh? I'll try and justify it.

There are fairly large practical difficulties such as the fact that the Atmocean CEO Phil Kithil in an interview as part of the BBC article says that "134 million pipes could potentially sequester about one-third of the carbon dioxide produced by human activities each year" - it's not clear whether this refers to current levels or not as by the time pipes were in place you'd need a lot more as we'll have chucked a whole lot more into the atmosphere, but anyway, installing that many pipes would be quite a task.

Creating phytoplankton blooms doesn't only increase the level of DMS in the atmosphere above the bloom, it also increases the levels of other gases, including methyl bromide and isoprene (see this paper) . Methyl bromide is a major source of bromide to the upper atmosphere and bromide is better at destroying ozone than the chlorine from CFCs, so this would have the potential to enhance ozone layer destruction. Isoprene has a complex, and not completely understood role in atmospheric chemistry - increasing the levels of these compounds in the atmosphere is likely to have an effect, which may be beneficial or otherwise, but as the roles of these compounds in the atmosphere are less well understood than DMS is stimulating their production wise?

There is also likely to be a massive impact on the biology of the sea; organisms have complex and subtle interrelationships that we are barely starting to understand, particularly at the microbiological level - how this will effect the climate is also unknown.

Charles Rapley points out in the BBC article that his and Lovelock's letter is designed to stimulate discussion about direct action, which I hope it will - international agreements like Kyoto being mired in political torpor, but there is a danger that such dramatic suggestions, that to non-scientists could sound like science fiction madness, only add weight to climate change apathy. It is the style of the solutions that captures the imagination rather than the problem itself (think giant solar reflectors in space and dumping iron filings in the sea).

However, if anyone can truly stimulate action it is Lovelock - his invention of the electron capture detector a sensitive device for measuring tiny amounts of chemicals in the atmosphere, prompted Rachel Carson's novel The Silent Spring, ultimately leading to the genesis of the entire green movement. For further reading James Lovelock's website is here.