As the gap between its models and reality has grown, the IPCC has become more adamant that its conclusions are correct – rather than more cautious.

The Intergovernmental Panel on Climate Change (IPCC) claims to be a rational, scientific body. But when scientists worthy of the name are wrong, they admit it. The IPCC does the opposite.

Once you peel multiple layers off the global warming onion, you’re left with computer models. According to these models, the small amount of warming that results when humans emit CO2 into the atmosphere is supposed to be amplified by other factors. It isn’t the CO2 itself but this amplification that the IPCC believes will lead to dramatic rises in temperature and dangerous consequences.

But here’s the problem: even though the real world hasn’t behaved as expected, the IPCC continues to cling to its position with a fervour that can only be described as religious.

Howard Hayden, who runs EnergyAdvocate.com, illustrates this with a brilliant image. He started with a graph produced by Roy Spencer that compares climate model projections with real-world data:

The thin lines represent 73 different climate model results, with the solid black line being the mean. The blue squares represent satellite measurements, and the green circles represent weather balloon measurements.

Hayden then added red arrows to Spencer’s graph, along with text boxes indicating the language the IPCC has employed over time.

Contrary to what any normal person would expect, as the gap between its models and reality has grown, the IPCC has become more adamant that its conclusions are correct.

In 2001, it thought it likely that human activity is responsible for much of the warming that has occurred since 1950. In 2007, it said this was very likely. Last month, it declared it extremely likely.

The IPCC equates “extremely likely” with 95% certainty. In the words of climatologist Judith Curry:

The 95% is basically expert judgment, it is a negotiated figure among the [IPCC] authors. The increase from 90-95% means that they are more certain. How they can justify this is beyond me. [bold added]

The IPCC is now the sweaty, haggard gambler at the roulette table. Having lost a horrendous amount of money on the last 15 spins, it’s obvious to everyone that he should push back his chair, walk away, and endeavour to regain his sense of perspective.

Instead, the IPCC has doubled down. It has chosen to squander what remains of its reputation at twice the speed.

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hat tip to Christopher Essex, who included the Hayden graph in a presentation a few days ago. With Ross McKitrick, Essex authored one the first climate skeptic books. Taken By Storm remains in the top three most-fun-to-read skeptic tomes of all time.

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see also

Quote of the Year: Climate Models Have Problems

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