Video description

On the 19th of July in 2011 the National Press Club of Australia held a debate on climate change. I will be analysing the claims Monckton made during the debate and if they are correct or not.

In this section of the debate Monckton says the following:

"...if you do climate by consensus, then the consensus is expressed in the documents of IPCC the inter-governmental panel on climate change. And they say that the climate is a coupled, non-linear, chaotic object and that, therefore, the long-term prediction of future climate states is not possible."

In this video I will be addressing this particular claim about the 2007 IPCC report and what the report actually says.

Transcript

STEVE LEWIS:
I'll now invite Lord Monckton to make his opening remarks. Lord Monckton, please.

LORD MONCKTON:
My Lord, that's me, ladies and gentlemen, the climate, like the cricket, is chaotic. Who would have believed that England would not only win back the Ashes but would then hang onto them the next time around? Just thought I'd rub it in.

[Laughter]

Now because the climate is chaotic, or even if it isn't, it acts as though it were, it is not predictable in the long-term. And that, if you do science by consensus - and that was the central argument that Professor Denniss offered us today, that there is a consensus - if you do climate by consensus, then the consensus is expressed in the documents of IPCC the inter-governmental panel on climate change. And they say that the climate is coupled, non-linear, chaotic object and that, therefore, the long-term prediction of future climate states is not possible.

This is a very strange statement as the IPCC has included projections about what our future climate might look like in every single report they published. They even give different types of outcomes, depending on the amount of greenhouse gasses we emit.

But he actually seems to be quoting from the 2001 IPCC report. One of the places this is mentioned is in the section “14.2.2.2 Balancing the need for finer scales and the need for ensembles” of the Working Group 1 report and it says the following:

In climate research and modelling, we should recognise that we are dealing with a coupled non-linear chaotic system, and therefore that the long-term prediction of future climate states is not possible. The most we can expect to achieve is the prediction of the probability distribution of the system's future possible states by the generation of ensembles of model solutions.

If you read the entire section you will find that they mention computational restriction as one of the reasons that limits them in the amount of detail they can include in the models. And lets not forget all the other factors that make it hard to project what happens. For example how much CO2 we emit, as this hinges on economic, social and technological developments.

Because of reasons like these it is not possible to give the one most likely scenario for how events will play out, its consequences and what the eventual future climate will be. But it doesn't mean you can't predict what might happen given a certain scenario.

The IPCC explains this in for example section “1.2.2 Natural Variability of Climate” of the Working Group 1 report:

Many processes and interactions in the climate system are non-linear. That means that there is no simple proportional relation between cause and effect. A complex, non-linear system may display what is technically called chaotic behaviour. This means that the behaviour of the system is critically dependent on very small changes of the initial conditions. This does not imply, however, that the behaviour of non-linear chaotic systems is entirely unpredictable, contrary to what is meant by “chaotic” in colloquial language. It has, however, consequences for the nature of its variability and the predictability of its variations. The daily weather is a good example. The evolution of weather systems responsible for the daily weather is governed by such non-linear chaotic dynamics. This does not preclude successful weather prediction[.]...

In other words what they say here, and throughout the entire report, is that complex systems like the climate can be predicted. We just have to be aware of where the limitations are and how we should deal with them. Which is a far cry from saying that our future climate cannot be predicted.

An illustration of what they mean with these uncertainties, one of them being climate noise, is given by Ben Santer, one of the IPCC authors:

[The General Public: Why Such Resistance? - 0:24:27 to 0:27:10]

This is from a climate model, a Japanese climate model, uhm, these are from experiments that were performed in support of the IPCC fourth assessment report in 2007.

What you see here are tropospheric temperature time series. And you can see that there is this black line here, this small overall warming trend. This is an experiment, or a model, that is driven by changes in greenhouse gases, changes in the sun's energy output, changes in aerosols in ozone. We call them also colloquially everything in the kitchen sink experiments, where you try and drive a climate model with your best estimate of the actual.. uh... factors that have been important over the twentieth century.

And you can calculate from this climate model something akin to the satellite temperatures that i've shown you. And in this particular run of this Japanese model you have a la-nina, that's that blue thing, near the end which tends to cool it down. And you have an el-nino near the beginning, that's the red thing, which tends to warm things up. Because this is a short record uh... only a little over twenty years, and you have a warm blip near the
beginning and a cool blip near the end you don't get much overall change.

Now when you run the same model, but starting from a different initial state, back say in 1850 or so, you get some different sequence of el-ninos and la-ninos. These are free running models if you will, they generate their own climate noise, and if you start from different initial conditions very soon you get a different sequence of el-ninos and la-ninas. You see that very clearly here. This is again the same model, the same human caused forcing factors that it's being run with, but it has a different sequence of el-ninos. In this case it has an el nino near the end of the series and a la-nina near the beginning so it shows a larger overall warming trend. Because it has a cool blip near the beginning and a warm blip near the end.

And you can see the same thing here, this is the same model just different realizations, and each one of them has a slightly different sequence of wiggles, ups and downs, different overall trends, this is the effect of noise. This is climate noise. Obviously in the real world we don't have the luxury of running the real world many times, we only have one sequence of climate noise and one sequence of how the real world has responded to human caused changes in greenhouse gases.

But in the climate model world you can essentially rerun the twentieth century many times and get many different sequences of these things. And what you do then at the end is you average over all of these things, you average over these five realizations, and that beats down the noise. Because the noise is not correlated from one realization to the next so you get a better estimate of the thing you're really interested in which is the slow overall increase in temperature. In this case in response to human caused changes in greenhouse gases and and all that other nice stuff.

So the IPCC report doesn't say they can't predict future climate states, as they can, and do, give predictions for likely future climate states.

Also I find it odd he's giving a direct quote from the IPCC 2001 report, when the report published in 2007 is the most recent one. Which also gives a similar statement about our chaotic climate system and what this means for predictions, albeit updated with the latest research.

Sources

1. Working Group I: The Scientific Basis - 14.2.2.2 Balancing the need for finer scales and the need for ensembles
2. IPCC Third Assessment Report
3. Climate Change 2007: Working Group I: The Physical Science Basis
4. Monckton responds to Skeptical Science

Media resources

1. Stanford University - The General Public: Why Such Resistance?