Monbiot's real mistake here is to swallow the conclusion of the Royal Society report on the subject, whole and undigested, without critical scrutiny or attention to other sources of information - in particular as regards the weathering of magnesium silicate (not enough Ca silicate to bother with):
Monbiot reports: "Dumping lime or calcium or magnesium silicates into the sea, where they react with carbon dioxide. Fairly safe. Effective. Expensive. Has the advantage of potentially reversing ocean acidification, but the amount of quarrying required to produce enough ground-up rock is likely to be prohibitive. " A) where does he get the idea that it's about dumping it in the sea? It is about spreading the rock powder on land, and in intertidal zones. B) So it's "fairly safe". Why only "fairly"? This is just to accelerate a natural process that is going on all the time anyway. C) "Expensive" - how much? People who have done the sums conservatively estimate $10-15 per tCO2. Making it one of the cheapest options around. D) It will only "potentially" reverse ocean acidification. Well, insofar as the science of chemistry "potentially" applies. He seems to be implying that maybe chemistry is "potentially" all wrong. George, tell us more! D) The amount of quarry is "likely to be prohibitive" - is it? Has he done the sums? Has he asked anyone who has done the sums? Or is this just his uniformed guess? For a start there are Gt of already mined rock that can be used, in mine tailings around the world. From then on, roughly 1t of rock sequesters 1t of CO2. So you need to mine an amount of rock comparable to the amount of fossil fuel we are burning. If it's not "prohibitive" to mine the coal, why's it "prohibitive" to mine the rock? Oliver Tickell. -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en.
