> Maybe you are overlooking something, e.g., that some species > are a source of food for humans.
The linkages being made between biodiversity and economic welfare seem very weak to me, particularly when considering which species are actually most endangered. If polar bears are in trouble, I just don't see why we couldn't help them out by feeding them, or vaccinating them against disease, or re- releasing them into the wild from zoos, and therefore I don't think there's much likelihood of them becoming extinct. As far as I know very few "large" species have become extinct recently. "Large" species are ones we can easily observe, and therefore it's not that hard to make sure we know they are still around. We'd notice pretty quickly, if there were no more elephants. If a small beetle in a small ecological niche in the Amazon basin goes extinct, we may never even have known the species existed. The kind of species where I think a major impact from climate change is plausible, is small in size, small in area inhabited, of recent speciation, and also small in terms of numbers of individuals or the total biomass they represent. And these species are also ones where I don't see why we should care much when they become extinct. Most of our food and most our pulp and paper and wood just comes from a tiny number of species grown in monocultures, where the farmer expressly tries to grow only one species and nothing else. Biodiversity in that context is known as weeds, disease and pests. Only for fish is there still a major take from eco-systems as opposed to high yield monoculture farms. Fish take from the oceans is something like a twentieth of world grain production, and even that little seems too much, and therefore, fish farming is in the process of becoming the major source of sea food. I know that a lot of scientists, particularly ecologists, feel differently about the economic important of species loss, and there are many intelligent people worried about it. But, when things get concrete as to how species loss would affect welfare, concrete beyond the general thought that eco-systems are complex and interdependent, and if one bit gets removed all the rest might fall apart in some fashion, the kind of examples I've seen don't involve much, if any, loss of economic welfare, and don't seem applicable to me, where the kind of species losses I see as plausible from climate change are concerned. Look at your shark (from overfishing of sharks) and bee (possibly related to the recent introduction of a particular pesticide) examples. It's not clear how much the value of fishing would change because of fewer sharks, after the bottom line is tallied it might turn out that the new eco-system balance actually favours some particularly valuable species. I saw this example in "The Economist", but couldn't find it with their search engine: http://oceanworld.tamu.edu/resources/oceanography-book/marinefoodwebs.htm Basically, after cod overfishing the food web changed and a new balance got established, but it turned out that the crab and shrimp fisheries resulting from the new food web where the cod never recovered, had greater economic value than the earlier food web favouring cod. With the bee example, I am doubtful that bees have much to fear from climate change, they've got a wide range and can easily move or be moved as required, and grow bees in the equivalent of zoos (/labs). As for polar bear I don't see them being lost. And being a technophile in the extreme, I wouldn't much mind, if we got rid of bees that can sting. It seems there already bees that can't sting http://opus.bibliothek.uni-wuerzburg.de/volltexte/2002/113/ and I woulnd't mourn the loss of stinging bees. As happens I was stung rather painfully into my tongue when I was eight, and if I had been a little bit less lucky and had been stung a bit further back towards the throat, I'd likely have been dead. --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
