Coby Beck wrote: > I don't think this is a fair criticism, it is simply noting that part of the > solution should be quite straightforward. This report surely can not make > assessments based on all kinds of possible realities exist today, it must > assume that all else is equal and then apply a climate change to the > situation.
No, if an assumption is made that "all else is equal" in a situation where all, in fact, is not equal and moreover where the unaccounted-for changes are likely to hugely outweigh the effect under consideration, then the outputs can hardly be considered as a useful prediction. It may be possible sometimes to dress up the extra effects as some uncertainty, but if they are likely to dominate the final result then the initial calculation seems rather futile (again, in terms of predictions - I've no beef with people trying to understand components of complex systems via standard reductionist techniques). Time for another example: ocean acidification. There have been a few papers (maybe several - here is the first I found http://www.nature.com/nature/journal/v407/n6802/full/407364a0.html ) where people basically put organisms into an acid bath (equivalent to 2 or 3x CO2 levels, in this case) to see how they like it. Not surprisingly, the answer is "not very much at all, especially if they have a carbonate skeleton (which is eroded by acid)". However, I think one might reasonably expect that 100 years of selective pressure (increasing at ~1% per year) would result in a substantial adaptation. Indeed it would be truly remarkable if this did not occur (and would strongly indicate that the effect did not actually represent a selective pressure at all). I know for sure that if someone suggested wiping out a pest or disease by gradually ramping up the ambient concentration of some antibiotic or pesticide by 1% per year, they would be laughed off stage - and rightly so. Of course, that Nature paper itself is couched in suitably moderate terms - lots of "could" and "might". But the scary picture of deformed coccolithophorids has been printed far and wide... My attention was also caught by an article in NewScientist some time ago about the rapidity of adaptation in respnse to human pressures. The point of interest seemed to be that this adaptation was much faster than people had previously thought: http://www.newscientist.com/channel/life/mg18725071.100-evolution-blink-and-youll-miss-it.html >> Incidentally, according to the paper, the reduction in yield and >> accompanying increase in hunger should be roughly linear with time/CO2 >> concentration, which suggests that it should perhaps be visible by now >> if it is a real effect (I don't know about interannual variability or >> quality of data collection though). Anyone know if there are data >> supporting this? > > I would think that the Green Revolution would hide any such effect over the > half century at least. And what are the implications of this for the "millions" who are "facing starvation"? Are they actual people, or merely an abstract mathematical artefact arising from a particular calculation? Is it unreasonable to expect that the "green revolution" would be (marginally) accelerated by the hint of rising food prices in the event of (barely detectable) climate changes? Remember, the cherry-picked results from the UNDP report were still only of the order of 0.5% pa reduction in potential yields in the *worst affected* areas. 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 -~----------~----~----~----~------~----~------~--~---
