Thursday, December 30, 2010

More On Climate Change Cost-Benefit Analysis

I seems to have struck a nerve with my recent post challenging the supposed damage of "climate change" by pointing out that to the extent it is real it would bring benefits as well as costs. It was a very long time since I got so much response to a post.

Most of the responses deserves no comment as they merely contain insults and personal attacks against me and/or simply repeat the response I mentioned in the original post of merely stating various alleged (and usually exaggerated as in the cases of sea levels and hurricane activity) costs without considering potential benefits. In other words, they don't really answer the question in any serious way.

For a review of the many benefits of global warming, I recommend Thomas Gale Moore's book "Global warming: a boon to humans and other animals" which is available online here. He doesn't really prove that the benefits are greater than costs, but the other side hasn't proven the opposite either. An honest discussion would try to weigh them against each other in a cost-benefit analysis.

There were however a few more reasonable and less emotional arguments, which does deserve responses.

One argument was that we really couldn't tell whether warmer weather would be on balance good or bad, because we hadn't experienced it, and that it wasn't worth the risk. But the right degree of risk aversion is always debatable, and besides, we have in fact experienced warmer weather than now, for example in the Bronze age and (at least in the North Atlantic) during the Medieval warm period. And there were no signs of civilizational decline during these periods.

Another argument concentrated on the supposed danger of carbon dioxide itself, rather than the indirect effect on warming. Yet carbon dioxide levels are currently only 385 parts per million, far less than the 10,000 parts per million where negative health effects are apparent. Even with a really dramatic increase in carbon dioxide emissions is levels going anywhere near 1,000, much less 10,000 parts per million. Furthermore, carbon dioxide is conducive to plant growth something which is good in itself and also limits the increase in carbon dioxide remaining in the air.

Another argument is that only during the last 12 millenia, after the last ice age, did agricultural civilization develop. Yes, but note that if there was a causal relationship, it was a causal relationship from warmer weather, something which Thomas Gale Moore mentions in his book. That would only suggest that the ideal climate isn't colder than right now, not that it's not warmer.

Another argument was that sudden changes in climate will be disruptive to existing ecological systems. This argument is actually partially true in the same sense that any economic change which causes transition problems.

But first of all, we don't know which way the climate would have changed in the absence of human intervention, as climate have changed and would have continued to change for other reasons. Human intervention could potentially counteract otherwise disruptive climate change. And secondly, big changes can be beneficial even if it is short-term disruptive, such as the death of the horse carriage industry following the introduction of cars.