Last Post today on Global Warming

I thought this fellow had an interesting discussion. There are, apparently, some forecasters who criticize the climate change forecasts because their validity is questionable in terms of forecasting methodology, not scientific methodology.

What are some of the main principles of forecasting? One involves the notion, so popular among orthodoxy advocates, of consensus. While consensus might say something about testable scientific theories, it says nothing about forecasts.

Armstrong and Green say: "Agreement among experts is weakly related to accuracy. This is especially true when the experts communicate with one another and when they work together to solve problems, as is the case with the Intergovernmental Panel on Climate Change process."

Apply this to another field, the stock market. If all of the stock pickers in the country, so-called experts, picked the same stock would you necessarily expect it to go up?

Many people believe these complex forecasts can be trusted because computer models are used. But so much uncertainty and subjectivity is involved in the input that Armstrong and Green say the use of these computer models is just a modern version of an old practice: the use of mathematics to make personal opinions sound more impressive. (Robert Malthus's predictions on population increase and food decline, very influential in the 19th century, were presented with a lot of mathematics. They were wrong.)

Armstrong and Green note: "To our knowledge, there is no empirical evidence to suggest that presenting opinions in mathematical terms rather than in words will contribute to forecast accuracy."

It's interesting reading.