greyeyes: i just reread your post--i think we're offering you the wrong advice. there have been models evaluating the economic cost of global warming. check out the ipcc reports on climate change:
http://www.grida.no/climate/ipcc_tar/wg1/index.htm (there may be more recent reports).
also, there was a study a few years ago showing that the economic value of hunting down all sperm whales now is worth more than allowing managing the species. i can't remember the study author, but i'll try to hunt it down for you. the point was that, if you want to save whales, you need more than economic motivitation to do so.