Oh Snap, Global Warming!

BUENOS AIRES, Argentina - Thousands of Argentines cheered and threw snowballs in the streets of Buenos Aires on Monday as the capital's first major snowfall since 1918 spread a thin white mantle across the region.

Wet snow fell for hours in the Argentine capital, accumulating in a mushy but thin white layer late Monday, after freezing air from Antarctica collided with a moisture-laden low pressure system that blanketed higher elevations in western and central Argentina with snow.

Don't you just love stories like this?

"This is the kind of weather phenomenon that comes along every 100 years," forecaster Hector Ciappesoni told La Nacion newspaper. "It is very difficult to predict."

Really? It's difficult to predict the weather, you say? Sir, could you tell what the climate will be like in 50 years, please? (hehe)

The snow followed a bitter cold snap in late May that saw subfreezing temperatures, the coldest in 40 years in Buenos Aires.

The coldest in 40 years, you say? Really!

OK, that's enough lighthearted fun directed at the global warming zealots. Now let's talk seriously--about forecasting.

Professor Scott Armstrong is at the Wharton School at the University of Pennsylvania. Dr Kesten Green is with the Business and Economic Forecasting Unit at Monash University. They're experts in forecasting techniques. (Many people are unaware that forecasting is a subject with many academic experts and a body of research going back to the 1930s. The website forecastingprinciples.com attracts more than 200,000 visitors a year.) Their paper is Global Warming: Forecasts by Scientists Versus Scientific Forecasts. It was written for the 27th Annual International Symposium on Forecasting.

Armstrong and Green looked at the Intergovernmental Panel on Climate Change's Working Group 1 report from earlier this year. This is the major source for the orthodoxy.

They focused on chapter eight, which sets out the methodology used for the forecasts in the report. They found that the panel, despite its immense assembly of scientific talent, appeared to have no idea of how to make a reliable forecast. Although the chapter has 788 references, none relates to forecasting methodology.

Armstrong and Green rated the methodology used by the panel against 89 principles of good forecasting derived from years of research. They found that the panel report breached 72 of those principles. They concluded that the forecasts the weather was likely to change in many negative ways were worthless.

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."

Another principle involves uncertainty and complexity. The more of each you have, the less sure you should be of your forecasts. Climate forecasts involve so many factors and so much uncertainty that Armstrong and Green believe they're useless.

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."

Update, 7/10/07: You have to admire someone who can write like this:

I COULD not have upset the soft-left, soft-green middle classes more if I had crept in their kitchens and snuck genetically modified tomatoes in their paninis.

And what does he say about global warming?

So what was our conclusion, after months of research that involved talking to hundreds of scientists and wading through mountains of science papers? It's all codswallop.

Previously we've heard it described by a well-respected climate scientist as hooey. I don't even know what codswallop is, but I'm guessing it's not good.

Update #2, 7/10/07: When SCIENCE Magazine starts backing away from the topic, you know the lefties are in a hurtbox. Thanks to reader EllenK for pointing me to this piece.