[EMAIL PROTECTED] wrote: >> Clearly none of the direct extraction methods seem close to viable in >> current economic terms, but I wouldn't like to say it will still be >> impossible in 100 years or more! > > But is that because of unpredictable technological developments, which > because they are unpredictable we mighn't want to rely on, or because > of quite anticipateable economic trends?
Mainly uncertainty in technology, although it shouldn't be forgotten that there is a fairly secure floor to the energy costs of several sequestration approaches. If society collapses then they will have bigger things to worry about anyway. > Currently, you wouldn't want to dedicate a nuclear plant to removing > CO2 from the air, you'd produce electricity and displace coal > generation. As long as nuclear is cheaper than coal, that even gives a > negative cost per tonne of CO2 avoided/removed. > > When, say sometime beyond 2100, there are no more coal fired power > plants, and assuming there's a willingness to spend 2% of GDP purely > to remove CO2 from the atmosphere, things look different. It is also possible that CO2 capture (eg via sea-based wind/solar powered stations) could be used to offset part of our emissions, rather than to engineer an absolute decline in atmospheric concentration. Of course that will only happen if the costs work out right. > Presumably, if sea level were to rise by 5 m New York and London > wouldn't just be abandonned, but a few hundred billion would be > invested in dikes (unless London in 2100 resembles Somalia today, in > which case retreat shouldn't be too costly, because most of the city > would be in ruin anyway). I guess so, although it also may depend on the time scale. I don't know how widespread it is (or widely known), but Japan has been building substantial artificial islands for over 150 years. That may be a better approach than dykes. Oh, Nice airport seems to be an artificial island too, now I think about it. Coincidentally, this news story seems relevant: http://environment.guardian.co.uk/climatechange/story/0,,2016243,00.html?gusrc=rss&feed=1 It seems to refer to the SPM of WG2. Again I'm sure the notion of committed change rests on the assumption that the temperature will not come down, although this is not made explicit in the article. I wonder how explicit it is in the real documents? James --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups Global Change ("globalchange") newsgroup. Global Change is a public, moderated venue for discussion of science, technology, economics and policy dimensions of global environmental change. Posts will be admitted to the list if and only if any moderator finds the submission to be constructive and/or interesting, on topic, and not gratuitously rude. 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/globalchange -~----------~----~----~----~------~----~------~--~---
