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Forecasts all up in the air

Article from: The Courier-Mail

Bob Carter

June 30, 2007 12:00am

KEVIN Trenberth is head of the large US National Centre for Atmospheric Research and one of the advisory high priests of the UN's Intergovernmental Panel on Climate Change (IPCC).

A New Zealander by birth, Trenberth has had a distinguished career as a climate scientist with interests in the use of computer General Circulation Models (GCMs), the basis for most of the public alarm about dangerous global warming.

When such a person gives an opinion about the scientific value of GCMs as predictive tools, it is obviously wise to pay attention.

In a remarkable contribution to Nature magazine's Climate Feedback blog, Trenberth concedes GCMs cannot predict future climate and claims the IPCC is not in the business of climate prediction. This might be news to some people.

Among other things, Trenberth asserts ". . . there are no (climate) predictions by IPCC at all. And there never have been". Instead, there are only "what if" projections of future climate that correspond to certain emissions scenarios.

According to Trenberth, GCMs ". . . do not consider many things like the recovery of the ozone layer, for instance, or observed trends in forcing agents".

"None of the models used by IPCC is initialised to the observed state and none of the climate states in the models corresponds even remotely to the current observed climate.

"The state of the oceans, sea ice and soil moisture has no relationship to the observed state at any recent time in any of the IPCC models.

"There is neither an El Nino sequence nor any Pacific Decadal Oscillation that replicates the recent past; yet these are critical modes of variability that affect Pacific rim countries and beyond . . . the starting climate state in several of the models may depart significantly from the real climate owing to model errors" and "regional climate change is impossible to deal with properly unless the models are initialised".

GCMs "assume linearity" which "works for global forced variations, but it cannot work for many aspects of climate, especially those related to the water cycle . . . the science is not done because we do not have reliable or regional predictions of climate".

Strange that. I could have sworn that I heard somewhere that the science was supposed to be settled.

One wonders whether anyone has told CSIRO that their much-vaunted regional climate models are worthless predictive tools. Perhaps someone will ask the CSIRO to refund the swingeing amounts state governments and others have paid for useless regional "climate forecasts"?

Trenberth's statements are a direct admission of the validity of similar criticisms that have been made of GCMs and the IPCC by climate rationalists for many years.

Of course, his tail-covering assertion that the IPCC doesn't make climate predictions or forecasts anyway has to be taken with a grain of salt. In a paper being presented at the 27th International Symposium on Forecasting in New York this week, Scott Armstrong and Kesten Green audit the relevant chapter in the IPCC's latest report. They find that "in apparent contradiction to claims by some climate experts that the IPCC provides 'projections' and not 'forecasts', the word 'forecast' and its derivatives occurred 37 times, and 'predict' and its derivatives occur 90 times" in the chapter.

Strange that the public has this misimpression that the IPCC predicts future climate, isn't it?

Having analysed the IPCC's approach in detail, Armstrong and Kesten conclude that "because the forecasting processes . . . overlook scientific evidence on forecasting, the IPCC forecasts of climate change are not scientific".

Like Trenberth's advice, this also may well be news to some people.

In a third devastating blow to the credibility of climate forecasting, a lead author of the IPCC Working Group 1 science report, Jim Renwick, recently admitted "climate prediction is hard, half of the variability in the climate system is not predictable, so we don't expect to do terrifically well".

Renwick was responding to an audit showing the climate forecasts issued by New Zealand's National Institute of Water and Atmosphere were accurate only 48 per cent of the time.

In other words, one can do just as well by tossing a coin.

These various criticisms of climate modelling can be summed up in the following statement – there is no predictive value in the current generation of computer GCMs and therefore the alarmist IPCC statements about human-caused global warming are unjustified. Yet Australia has an Opposition and a Government that profess to set their climate policies on the basis of IPCC advice. Both also seem determined to impose an inefficient, ineffective and costly carbon trading or taxation system on the economy, for the aspirational absurdity of "stopping climate change".

Perhaps someone should tell Prime Minister John Howard that dangerous global warming has been called off.

Professor Bob Carter is a James Cook University geologist who studies ancient environments and climate. His website is at: 

CHANGING seasons ... global warming has been called off.

Have Your Say

Latest Comments:

Yeah let's listen to a professional PC gamer on climate change = lol. Ostrich syndrome is not for the rest of us. We will er on the side of caution.

Posted by: Mark of Canberra 2:31pm today

Prof. Jon Jenkins sums up the scam that is human induced climate change (HICC) very well.

Well said Prof!

Posted by: Patrick Davis of NSW 3:04pm July 02, 2007

What if a handful told you there was a bullet in the gun or better yet a nuclear trigger? Would you want to pull the trigger?

Posted by: Gary Kimlin of 10:18pm June 30, 2007

If 2,500 scientists tell me there is bullet in the gun and a handful tell there may not be maybe - I wont be pulling the trigger. Some of course would like to take a gamble and wait and see, then get in their time machines if they are wrong.

Posted by: Debbie of Darwin 2:28am June 29, 2007

Many thanks to the Courier-Mail for publishing another superb article by Bob Carter. It's great to see more articles like this instead of all the usual "Global Warming fear-mongering claptrap" that is thrust upon us all the time. Finally, Al Gore's propanganda is beginning to unravel very quickly, and speaking of Gore, I see that his Live Earth Fright Festivals of Fear are also falling apart. The Istanbul/Turkey event has been cancelled and the South African event has been drastically downsized to a much smaller venue and ticket sale have been a disaster!

Posted by: Nick Stefanos of 7:56pm June 28, 2007

hmm, perhaps the reason he's backing away from claiming they were predicting change is that the model has underestimated the rate of change ? Look at how fast the Arctic ice cap is melting. Many times faster than the models predicted. I don't see anything in the article to say that there isn't climate change happening, just that the predictive models aren't as accurate as once thought. That inaccuracy could go either way - either overestimating or underestimating. Of course the naysayers have always latched on to this uncertainty as proof that nothing is happening.

Posted by: Troy of Kenmore of Kenmore 7:33pm June 28, 2007

Bob Carter has quoted Kevin Trenberth in a highly selective way here. Perhaps he didn't read the rest of his blog, like this paragraph,

"The IPCC report makes it clear that there is a substantial future commitment to further climate change even if we could stabilize atmospheric concentrations of greenhouse gases. And the commitment is even greater given that the best we can realistically hope for in the near term is to perhaps stabilize emissions, which means increases in concentrations of long-lived greenhouse gases indefinitely into the future. Thus future climate change is guaranteed."

The one immediately after also seems a bit at odds with Bob's position,

"So if the science is settled, then what are we planning for and adapting to? A consensus has emerged that ¿warming of the climate system is unequivocal¿ to quote the 2007 IPCC Fourth Assessment Working Group I Summary for Policy Makers (pdf) and the science is convincing that humans are the cause. Hence mitigation of the problem: stopping or slowing greenhouse gas emissions into the atmosphere is essential. The science is clear in this respect."

People can find this post at

Reading it and making up your own mind might be better than letting Bob do it for you.

Posted by: Jamie Riches of 5:07pm June 28, 2007
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