Firstly, look at the numbers involved, 4 billion tonnes of limestone will need to be applied to the oceans on a constant basis over the next 100 years. As Harvey (2008) himself pointed out, the sheer magnitude of the infrastructure involved would be huge. To mine, grind and transport that amount of limestone would be a huge undertaking, so would it all be worth it? The emissions from this infrastructure effort alone could render the operation pointless. Also that's a lot of limestone, could it have more effective uses? Perhaps.
Lenton and Vaughan (2009) have pointed out that on a 100 year timescale, increasing ocean alkalinity could prove wholly ineffective and could only be effective on a 500 year timescale, that's 20 billion tonnes of limestone!
Cullen and Boyd (2008) have also voiced concerns about what increasing alkalinity could do to ocean chemistry, although their concerns are based around addition of phosphorus and iron, altering ocean chemistry on such a big scale could have drastic consequences.
Also the point that limestone quarries are almost always met with opposition from campaigners cannot be ignored. The mining of this mineral is seen to leave a 'scar' on landscapes and increased mining isn't going to be met with open arms.
Personally, this scheme seems to be quite a huge undertaking and something that is very expensive. Would policy makers be willing to risk money a project that isn't guaranteed to work, that is based around assumptions? It doesn't seem likely.
Hi Sam - I have to agree with you in that I don't think that they will go for this. Besides it's one thing coordinating international emission agreements and quite another to have multiple countries actually working on the same project. As you have also mentioned, I would also be concerned about the side-effects from putting this into place. On the one hand if they did go for this then it would be great in terms of how serious they are taking the issue but I think there must be a better way than this - have you come across any?
ReplyDeleteThanks for the interesting post!
Yeah well there are a few schemes which would have less dramatic consequences if they went wrong, such as BECS however the scope for the amount of carbon dioxide that would be stored isn't anywhere near the numbers of limestone addition.
ReplyDeleteI just can't see a project like this ever taking place if I'm honest, at the moment world leaders can't really agree to much about climate change so schemes like this are currently pie in the sky!