Climate science in the media in the run-up to AR5

23 09 2013

The past few days have seen a big increase in media coverage of climate science as the world awaits the release of the IPCC’s AR5 WGI report at the end of this week.

Media stories have focused on a wide range of issues, with some looking at Arctic sea ice and others claiming that climate models exaggerate the rate of future warming.

In fact it has just been announced that this year Arctic sea ice reached its sixth lowest minimum extent since satellite records began in 1979 and all those years have occurred in the last decade. The long-term decline of Arctic sea ice is one of the most visible of many different signs that our world is warming – a point which few people dispute.

It is also well-established that if we increase concentrations of greenhouse gasses in the atmosphere, then global temperatures will rise. The debate is about how much the world will warm, where it will warm fastest and what the implications are for us.

Today an article by the GWPF think-tank looks at one element of this – the UK’s official climate projections, known as UKCP09, which were produced by the Met Office.

It claims the Met Office climate model used to make those projections, HadCM3, contains an error and that, because of this error, the projections overestimate warming. The GWPF’s article, however, accepts that the claims of an error have not been substantiated.

UKCP09 used a sophisticated method that used both model projections and observations to provide a range of potential future warming which attempts to take in the uncertainties in model parameters. The GWPF article fails to note that UKCP09 also used information from many other climate models, and that the projections were independently reviewed prior to publication.

Ultimately there is nothing in the GWPF article which undermines UKCP09 or the way climate models, including the Met Office’s HadCM3, project future temperature changes.


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23 09 2013
niclewis

As I am the author of the document (see http://niclewis.files.wordpress.com/2013/09/metoffice_response2g.pdf ) that is the source of the GWPF’s claims about the use of the HadCM3 model to generate the UKCP09 projections, I am responding to the counterclaims made by the Met Office in this news article

I didn’t claim that the HadCM3 model contained an error (and nor, so far as I can see, does the GWPF document claim it did, contrary to what is stated). I wrote that, since the observational data strongly contraindicate aerosol forcing being highly negative, “whatever the actual level of ECS [climate sensitivity], HadCM3-derived ECS estimates are bound to be high.” This indicates that the HadCM3 study was unsuitable for use in generating projections that are, supposedly, constrained by observations.

The Met Office claimed in their July report The recent pause in global warming(3) that, in the Harris et al 2013 study underlying UKCP09 “uncertainty in the response of the climate system to CO2 forcing is comprehensively sampled”. That is clearly incorrect.

The statement “The GWPF’s article, however, accepts that the claims of an error have not been substantiated.” is misleading since it suggests that the claims referred to in the article (those in my critique of he Met Office report) have been refuted. They most certainly have not been refuted. The Met Office has not yet even made a substantive response to my claims.

The statement says “UKCP09 used a sophisticated method that used both model projections and observations to provide a range of potential future warming which attempts to take in the uncertainties in model parameters.” deserves comment. The method was indeed sophisticated, and there were attempts to take in uncertainties about model parameters. I said as much in my critique of the Harris et al 2013 study. But sophisticated does not imply valid, and attempts are not always successful. And in fact the taking into account in the study, within limits, of uncertainties in model parameters did not enable the HadCM3 model to simulate a climate system in which both climate sensitivity and aerosol forcing were modest, as suggested by several recent observational studies.

The statement that “the projections were independently reviewed prior to publication” is irrelevant. It is doubtful whether any reviewer would have spotted the problem that I have identified, which involved some detailed analysis and modelling work.

The use of information from other climate models that is referred to is also irrelevant, since use of that information did not overcome the fundamental problem – the inability of the HadCM3 model to simulate a climate system in which both climate sensitivity and aerosol forcing are modest.

The Met Office have not provided any justification for the unsupported claim that “Ultimately there is nothing in the GWPF article which undermines UKCP09 or the way climate models, including the Met Office’s HadCM3, project future temperature changes.”

24 09 2013
jbenton2013

Yet more weasel words and obfuscation from the Met Office. The fact is that Arctic sea ice has increased 60% in 2013 from 2012 levels, not that you would know from this article. Last year when Arctic sea ice fell there were all sorts of dire predictions but when it increases by 60% there are still dire predictions. Is it any wonder the public have stopped believing anything climate scientists say when all we gat is spin.

Likewise when all the climate models failed to predict the 16 year stop in warming the Met Office is still implying the models are accurate, and what evidence do you put forward for this assertion, why it’s predictions from other models which are equally useless. Whether your predictions were “independently reviewed prior to publication” is entirely irrelevant, wrong is wrong. The fact that other models are equally wrong will not impress anyone.

24 09 2013
alan watt

Surely it is the duty of the MET office to substantiate or abrogate claims of errors in their models. Press releases stating that other models were used and that the models were independently reviewed do not negate claims of error.

25 09 2013
nuwurld

More “utter rubbish” being spouted about “greenhouse” gas concentrations. Laughable. Oh except mitigation is going to cost us billions. For nothing!

Nature produces 95.5% of CO2 annually whilst adapting to absorb biologically, 50% of man’s emissions in positive plant growth.

The climate will follow the solar decline lasting the next few decades. Once the thermal inertia of the various heat capacities catch up the decline in temperature will be embarrassingly evident for climate science.

25 09 2013
jbenton2013

If this is the best the Met Office can come up with to refute the GWPF article then politicians must consider whether continued funding of the Mey Office can be warranted. At the very least the senior management of the organisation must be replaced by competent personnel of integrity.

25 09 2013
ntropyalwayswins

If our ‘world’ is warming no-one told the Antarctic.

The world appears to have stopped warming in 1998. It may start to warm again but according to the UK Met Office this is not expected for the next 5 years. So one has to ask if the use of the phrase ‘our world is warming’ can be justified?

What the citizens of the UK are perhaps more interested in is the temperature trend over recent years in the Uk, particularly in winter, when we need cheap energy to keep warm. What the hapless citizens of UK have actually had is a double wammy. Artificially expensive energy and colder winters. And all thanks to the Met Office choosing to do spin rather than science.

And what does the penultimate paragraph of your piece mean? Meaningless waffle.

Your failure to address the point made by Nic Lewis makes you look ridiculous.

0/10 must try harder

26 09 2013
ntropyalwayswins

Further evidence that the Met Office is not for purpose can be found here http://www.bishop-hill.net/blog/2013/9/26/steve-jewson-on-bayesian-statistics.html#comments

Time the MO hired some grown-ups to help crunch the numbers but then you don’t appear to be interested in doing the job properly?

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