Global warming

Everyone seems to be holding themselves out as experts on global warming these days, even those who patently are not. Here is my take on it. It is a three pointer so bear with me.

1. There is a graph which has been published ad infintum that shows how the earth's temperature has varied with the amount of carbon dioxide in the atmosphere over the past few thousand years. When CO2 is high, so is temperature. Most scientists agree that this occurs since carbon dioxide enhances the natural greenhouse effect (trapping of solar radiation) of the atmosphere. I believe all this and so would expect the earth's temperature to rise as atmospheric CO2 levels rise.

2. I don't think anyone knows how fast the temperature will rise and what effect that will have. Many learned scientists, including those from the IPCC (International Panel for Climate Change), have tried to predict what is going to happen, and there are many disagreements. The IPCC don't help themselves by trying to predict far into the future. As has been pointed out, notably by Nigel Lawson in his book "An Appeal to Reason", attempting to predict how the world will look in 100 years is farcical.

I think one of the problems with predicting future climate is that the earth's atmosphere is a complex convection system, complex enough that we cannot accurately predict the weather more than a few days in advance. We can make broad generalisations about what might happen in future, but the effect of intial uncertainties, potential feedbacks (eg melting of ice reducing albedo and enhancing warming) and lack of knowledge of how humans will react to the problem, in my view really mean that the future is very uncertain. There are however a number of potentially damaging outcomes of global warming, which in the worst case could see major human (and natural) catstrophe.

3. So we have something happening, the outcome of which is uncertain but can reasonably be supposed to be unpleasant. So what do we do? My approach is based on Pascal's wager. Pascal orignally made his comments about belief in God, but belief in global warming is now somewhat analogous to the position in which Pascal found himself when considering whether to believe in God.

In summary:

a) If we believe that the earth wil be destroyed through climate change and we are correct, our actions now to reduce CO2 will have saved the planet.
b) If we are wrong, we will have lost little through our actions.
c) If we do nothing now in the belief that climate change is not a danger and we are correct, we will be slightly better off.
d) If we do nothing now and we are wrong in that belief, there is trouble ahead.

Simple really. Something bad (possibly catastrophic) might happen in the future and we can take action now that will probably stop it. I think we should take that action.