In a previous post on terraforming, I suggested that "To some extent, the terraforming debate was a creature of the eighties and nineties. This is why I tend to doubt the idea that 'increasing numbers of researchers' are taking the time to think seriously about terraforming. They're too busy with Mars as it is to work hard on ideas about how to engineer its future...Ideas about terraforming flourished at a time when there seemed a fairly solid model of Mars based on the Viking data, and people interested in Mars had the time to engage in thrilling thought experiments on the basis of that model. Now there is a torrent of new data and no time for thought experiments." Looking back, I still think that's right, as applies to Mars. What I didn't mention at the time was that it's clearly not the case as applies to earth.
Terraforming ideas for the earth -- maybe "planetary engineering" is the right term -- have clearly grown in number and seriousness over the past decade, and continue to do so. The most obvious example is the continuing research interest in iron fertilisation of the oceans. Various parts of the ocean -- notably the southern ocean around Antarctica -- offer all the nutrients needed for photosynthetic plankton to grow, except iron. The late James Martin suggested that during ice ages, increased amounts of iron-rich dust would settle in these areas, increasing the productivity of the plankton there. More productive plankton draw down more carbon dioxide, thus keeping the atmospheric greenhouse thin and the world cool. If that is how the world is kept cool in an ice age, Martin suggested, it might be a way of keeping the earth cool now, when it seems at risk of overheating.
This idea has now been looked at by seven experiments in which tens or hundreds of square kilometres of ocean surface waters are given an relatively modest iron booster. As a result, the fact that iron fertilisation can indeed spur fairly spectacular photosynthetic plankton growth, as measured by the amount of chlorophyll in the water, is undoubted; the New-Zealand-led SOIREE experiment produced a phyoplankton bloom clearly visible from orbit with just a few tonnes of iron. Last week there was a set of reports on the 2002 SOFeX experiments in Science magazine. Some of the details are quite intriguing: Philip Boyd of the SOIREE team, commenting on the results in Science (subscription required, I'm afraid) points out that SOFeX showed iron fertilisation to work even in water that contains little silica, which may be linked to the fact that nitrogen is not lost from the surface waters as quickly as the carbon is.
After all this experimentation, though, it is still not clear whether iron fertilisation can in fact draw down large amounts of carbon dioxide and squirrel the stuff away in the deep ocean. The plankton in the surface waters clearly love the added iron, but only a small part of the carbon they take up goes on to sink into the deep ocean where it can't get back into the atmosphere. The fact that SOFeX managed to sink 2,100 tonnes of carbon with just over a tonne of iron may sound pretty impressive. But as Boyd and Ken Buesseler of Woods Hole pointed out in another Science article, you need to do hundreds of times better than that in order to start making a cost-effective dent in the global level of carbon dioxide; we'd need a million SOIREE or SoFEX sized fertilisations every year to get rid of 30% of our annual carbon dioxide emissions. It's obviously likely that we could find more efficient ways than today's experiments are using to get larger amounts of iron into much greater areas of the surface ocean. But whether you can get the sort of efficiency gain that seems necessary to tackle the crabon dioxide increase is unclear. Just as importantly, it's also unclear what knock-on effects any attempts to move in that direction would have on other aspects of ocean biogeochemistry. Might more iron lead to less phosphate in the oceans, and thus more nitrous oxides and methane in the atmosphere, which would end up enhancing the greenhouse effect? The number of unknowns is still vast, and claims that fertilisation is already a practical way of offsetting the build up of carbon dioxide are clearly very premature.
The ocean fertilisation experiments are not the only evidence that planetary engineering is a growing concern; a number of other cooling schemes are under discussion. It all adds up to a lot more interest in -- and investment in -- terraforming-type activities than Mars has ever generated. No surprise there; we are already changing the climate of the earth, and it's right and proper that people should be looking at ways to control that change, or reverse it, using large scale engineering, biological or otherwise. We need the options to make informed policy.
So terraforming discussions are not quite the narrowing niche I may have suggested. It's just that at the moment, most of them are concerned with changes a little closer to home. An interesting aspect of this change in focus, pointed out by a biologist friend who says he's hearing more and more of his post-genome buddies speculating about ways of hacking biogeochemical cycles, is that the people discussing terraforming the earth are far less likely to have read the relevant science fiction than people discussing the terraforming of Mars. My biologist friend -- someone who definitely has done the SF reading -- thinks that this is a pity, and I tend to agree.
The new planetary engineers could do a lot worse than look at the chunk of Jim Oberg's book New Worlds that he has just posted at Spacedaily. New Worlds, originally published in 1981, was the first book-length non-fictionwork on terraforming, and among many other virtues it gives proper weight to the idea's development in science fiction.
Terraforming & Energy. The sun, being are true source of energy, could give us more energy if we wanted it (for Earth or Mars). If a lense were sent closer to the sun, but focused light on a specific place on the planet it could send enormous energy to Earth or Mars. This energy could be used to melt frozen CO2, or simply turned into electricity on Earth.
Posted by: I Sharp | July 25, 2005 at 03:39 AM
This is true, Isaiah. But in the case of the earth I'd be more interested in averting change just by using more of that sunlight, focused or not. The sun provides more energy to the earth in an hour than we get from burning fossil fuels in a year...
Posted by: Oliver Morton | July 25, 2005 at 07:38 AM