Education and Careers

Q: I have a silly idea involving 'Snails that eat refuse', and we use the calcium from their shells to put in Jet fuel and reflect the suns rays, (Global dimming),and as the calcium grabs the carbon dioxide from the atmosphere, and the sea, as it falls to earth, it fertilises everything?

From Dave Lamb (September 2009)

Reply by Dr Ted Nield

Thanks for your interesting idea about shooting snails into the upper atmosphere. The main problem I foresee with your scheme is that there is a zero sum there, chemically. The snail shells are calcium carbonate, which if shot through a jet engine (assuming that is technically possible!) would dissociate into ions that would then on cooling form carbon dioxide and calcium oxide. The calcium oxide might possibly have some reflecting effect and by increasing the Earth's albedo might counteract global warming; but eventually the only carbon dioxide that would be swabbed out of the atmosphere would be the same carbon dioxide that you had already liberated.

Putting CO₂ into solid form (limestone) is Earth's natural homeostatic response to increases in atmospheric CO₂; problem is it's too slow to cope with the current extra anthropogenic supply.

I expect that growing snails - especially edible ones - is a good idea. It would allow us to put more snail shells into landfill, which would effectively lock up the CO₂ for a good long time - as anthropogenic limestone! Not sure I want to eat a snail fed on refuse though.

Your idea falls into the category of grand "geoengineering" projects that tend to make me nervous (counteracting one uncontrolled experiment by starting another!) but which were recently discussed at a special meeting of the Royal Society.