Dr Roy Spencer: GW predictions based on faith, not science

Dr Roy spencer explains why climate modellers can tune their models to achieve just about any rate of warming they like:

The ‘consensus’ IPCC view, on the left, would be that the 1 deg. C increase in temperature was the cause of the 1 Watt increase in the Earth’s cooling rate. If true, that would mean that a doubling of atmospheric carbon dioxide by late in this century (a 4 Watt decrease in the Earth’s ability to cool) would eventually lead to 4 deg. C of global warming. Not good news.

But those who interpret satellite data in this way are being sloppy. For instance, they never bother to investigate exactly WHY the warming occurred in the first place. As shown on the right, natural cloud variations can do the job quite nicely. To get a net 1 Watt of extra loss you can (for instance) have a gain of 2 Watts of forcing from the cloud change causing the 1 deg. C of warming, and then a resulting feedback response to that warming of an extra 3 Watts.

The net result still ends up being a loss of 1 extra Watt, but in this scenario, a doubling of CO2 would cause little more than 1 deg. C of warming since the Earth is so much more efficient at cooling itself in response to a temperature increase.

As a result of this inherent uncertainty regarding causation, climate modelers are free to tune their models to produce just about any amount of global warming they want to. It will be difficult to prove them wrong, since there is as yet no unambiguous interpretation of the satellite data in this regard. They can simply assert that there are no natural causes of climate change, and as a result they will conclude that our climate system is precariously balanced on a knife edge. The two go hand-in-hand.

Their science thus enters the realm of faith. Of course, there is always an element of faith in scientific inquiry. Unfortunately, in the arena of climate research the level of faith is unusually high, and I get the impression most researchers are not even aware of its existence.

Read it here.