Poor old Baroness Verma

Further to yesterday's revelation that the government has abandoned the global temperature record as evidence of manmade climate change comes this new exchange between our two ennobled gladiators:

Lord Donoughue (Labour): To ask Her Majesty’s Government, further to the Written Answer by Baroness Verma on 8 November 2012 (WA 224–5) stating that “the temperature rise since about 1880 is statistically significant” and the Written Answer by Baroness Verma on 21 January (WA 99) stating that the Government do not use “purely statistical models” to analyse global temperatures, whether they will reconsider the earlier assertion that the rise in global temperatures since 1880 is “statistically significant”.

Baroness Verma (Conservative):  With regards to the Written Answer I gave the Noble Lord on 8 November 2012 (Official Report, Column WA 224-5), I have nothing further to add beyond my previous answers on this subject.

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+++Government abandons temperature records+++

Doug Keenan has just pointed me to a very interesting parliamentary question and answer. As ever the protagonists are our old friends Lord Donoughue and Baroness Verma, and once again the subject is statistical models. I've inserted some clarification suggested by Doug in brackets. This has no bearing upon the answer.

To ask Her Majesty’s Government, further to the Written Answer by Baroness Verma on 25 May 2013 (WA 44–5) which stated a linear trend model with first-order autoregressive noise [is very unlikely to be an appropriate model] in representing the evolution of global annual average surface temperature anomalies, and in the light of the Working Group I Contribution to the Intergovernmental Panel on Climate Change Fifth Assessment Report which states that statistical analyses of climatic time series “have to assume some kind of model, or restricted class of models”, what models they rely upon for statistical analyses of global temperature series; and why they chose those models.[HL4497]

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Unqualified evidence

Following my post on the Royal Meteorological Society's evidence to the AR5 inquiry, Doug McNeall and I had a long and interesting exchange on Twitter. Although he arrived at his point somewhat elliptically, Doug appeared to want to suggest that although in Ed Hawkins' graph the observations are on the cusp of falling outside the envelope described by 90% of model runs, this did not actually represent falsification. In his view, the test was too harsh.

The precise determination of when the observations should be seen as inconsistent with the models is one for the statisticians, and I know that Lucia, for one, disagrees with Doug's view (and I feel pretty sure that Doug Keenan will say that they are both wrong). However, this is not actually germane to my original point, which is that the poor performance of the models to date - as represented by Ed's graph - needs to be communicated to policymakers. We are without doubt less confident than we were that the model ensemble captures the true behaviour of the Earth, even if we are not (in Doug M's view at least) absolutely certain that it does not.

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On the limits to climatology

This is the abstract of Professor Leonard Smith's lecture at the AGU meeting currently taking place on the other side of the pond. There are salutary lessons for climatologists. If anyone can point me to the video, that would be helpful.

Over the last 60 years, the availability of large-scale electronic computers has stimulated rapid and significant advances both in meteorology and in our understanding of the Earth System as a whole. The speed of these advances was due, in large part, to the sudden ability to explore nonlinear systems of equations. The computer allows the meteorologist to carry a physical argument to its conclusion; the time scales of weather phenomena then allow the refinement of physical theory, numerical approximation or both in light of new observations. Prior to this extension, as Charney noted, the practicing meteorologist could ignore the results of theory with good conscience. Today, neither the practicing meteorologist nor the practicing climatologist can do so, but to what extent, and in what contexts, should they place the insights of theory above quantitative simulation? And in what circumstances can one confidently estimate the probability of events in the world from model-based simulations?

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Let them eat equality

The Oxford Martin School has appointed a "commission" of environmentalists to gaze at the future and come up with all sorts of plans to deal with it.

Deja vu.

The results were presented in a joint lecture by Martin Rees and Sir John Beddington last week and a video of the event is now available here. In it, we learn that the commissioners are proposing a cornucopia of new international bureaucracies, that some of them have a bit of a soft spot for totalitarian regimes (no short-termism, you see) and that they have decided that Lord Stern was right about low discount rates. This last one is not a surprise given that Lord Stern was in fact one of the commissioners.

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Speaking volumes

Mike Kelly has a letter in the Times today calling for an independent panel of statisticians and engineers to assess what the climatologists are telling us.

Sir, When I hear the Government’s Chief Scientific Adviser one week, and the Secretary of State for Business Innovation and Skills ten days later, with several members of the House of Lords in the interim, all referring to the Intergovernmental Panel on Climate Change (IPCC) as being more certain than ever of mankind’s role in changing the climate, but none of them qualifying the statement by admitting that man is still a bit player compared with the Sun and with nature over the past 150 years, then there is need for a really independent assessment of the interface between science and policy in this most important and contentious subject (Global warming battle “has become a religion” Nov 6).

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Keenan does AR5

Doug Keenan has written a critique of the IPCC's handling of statistics in AR5. Suffice it to say he is not impressed.

Temperatures on Earth ’ s surface — i.e. where people live — are widely believed to provide evidence for global warming. Demonstrating that those temperatures actually provide evidence, though, requires doing statistical analysis. All such statistical analyses of the temperatures that have be en done so far are fatally flawed. Astoundingly , those flaws are effectively acknowledged in the IPCC Fifth Assessment Report (AR5) . The flaws imply that there is no demonstrated observational evidence that global temperatures have significantly increased (i.e. increased more than would be expected from natural climatic variation alone). Despite this, one of the main conclusions of AR5 is that global temperatures have in creased very significantly. That conclusion is based on analysis that AR5 itself acknowledges is fatally flawed. The correct conclusion is that there is no demonstrated observational evidence for global warming.

You can read it here.

Keenan writes to Slingo

Doug Keenan has just written to Julia Slingo about a problem with the Fifth Assessment Report (see here for context).

Dear Julia,

The IPCC’s AR5 WGI Summary for Policymakers includes the following statement.

The globally averaged combined land and ocean surface temperature data as calculated by a linear trend, show a warming of 0.85 [0.65 to 1.06] °C, over the period 1880–2012….

(The numbers in brackets indicate 90%-confidence intervals.)  The statement is near the beginning of the first section after the Introduction; as such, it is especially prominent.

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Steve Jewson on Bayesian statistics

Steve Jewson is the statistician whose trenchant comments on climatologists' use and misuse of Bayesian statistics was discussed here some months ago.

This presentation he gave to a conference at the University of Reading is in similar vein, but goes beyond Bayes' theorem to areas such as the UKCP09 climate predictions.

UKCP

• unashamedly uses subjective methods

• Includes subjective beliefs that go beyond the models and the data

Nic Lewis has analysed the impact of these additional subjective factors:

• And it seems that they push the rate of climate change higher than that suggested by the evidence
• If true, then UKCP predictions of future temperatures would be higher than their own models and data would suggest
• And should not be expected to be ‘reliable’

Oh dear.

His conclusion - that the Met Office could easily strip the subjectivity out of their predictions - seems to me to be of critical importance. Time, I would say, for the empanelling of the review that Nigel Lawson called for.

Time series analysis for experts

One regular criticism that is made of climatologists is that their statistical analyses tend not to make use of up-to-date methods, particularly as regards time series analysis. This course in Germany therefore looks to be useful:

Advanced Course in Climate Time Series Analysis, Hannover, Germany, 20 to 24 January 2014

I'm not sure how advanced though:

• Level: academic (PhD students and postdocs), industry (researchers and analysts)
• Audience: Climatologists, Geographers, Geologists, Hydrologists, Meteorologists, Physicists, Risk analysts, Statisticians
• Basic knowledge in statistics is required (e.g., you should know what "standard deviation" means).

A pickle

The must-read post this morning is Judith Curry's coverage of a new paper by Kosaka and Xie in Nature. The paper received some attention yesterday, the BBC reporting that it explained the 21st century temperature plateau, saying it was due to...

natural cooling in part of the Pacific ocean.

Although they cover just 8% of the Earth, these colder waters counteracted some of the effect of increased carbon dioxide say the researchers.

But temperatures will rise again when the Pacific swings back to a warmer state, they argue.

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Kevin Trenberth is a very naughty boy

Lucia Liljegren has discovered Kevin Trenberth being naughty with one of his graphs. I mean very naughty.

One can...speculate why Trenberth didn’t compare the 12 year flat (and negative) trend ending in 2012 to 12 year ‘flat’ trends in the past. The current period is the only period with a “flat” (or negative) trend. Presenting that comparison would certainly give “impression[.] that the global mean temperature is not increasing at its earlier rate”.

Oh dear. Read the whole thing.

Update on Jun 14, 2013 by Bishop Hill

Trenberth is even naughtier than we thought.

Just remember folks, if you commit the sin of publishing sceptics, you have to apologise to Dr Trenberth.

On the meaning of ensemble means

Readers have been pointing me to this comment at WUWT. It's written by a reader calling themselves rgbatduke, and it considers the mean and standard deviation of an ensemble of GCM predictions and asks whether these figures have any meaning. It concludes that they do not.

Saying that we need to wait for a certain interval in order to conclude that “the models are wrong” is dangerous and incorrect for two reasons. First — and this is a point that is stunningly ignored — there are a lot of different models out there, all supposedly built on top of physics, and yet no two of them give anywhere near the same results!

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Show us your evidence

Updated on Jun 13, 2013 by Bishop Hill

Lord Donoughue's terrier-like pursuit of the observational evidence that we have experienced warming that is out of the ordinary continues unabated.

Lord Donoughue (Labour): To ask Her Majesty’s Government whether they have identified any observational evidence for statistically significant global warming, either natural or anthropogenic; and, if so, from what sources any such evidence originated.

Baroness Verma (Whip, House of Lords; Conservative):  There is considerable observational evidence that the world has experienced statistically significant warming since the end of the 19th century. This is reported in Section 3.2 of the IPCC’s 4th Assessment Working Group I Report1.

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More parliamentary statistics

Parliamentarians still seem to be showing an admirable interest in the nitty gritty of statistics as applied in the climate change field. Here's a question and answer exchange between Peter Lilley and Greg Barker:

Lilley: To ask the Secretary of State for Energy and Climate Change what assessment his Department has made of whether the decrease in the extent of Arctic sea ice since reliable records began is statistically significant; and what statistical model his Department has used to conduct that assessment.

Barker: The Department has not commissioned any assessment of the statistical significance of long-term trends in Arctic sea-ice extent. Work undertaken under the Climate Programme at the Met Office Hadley Centre has assessed the physical reasons for the decrease in ice extent and used physically-based climate models to assess its future course ('Assessment of possibility and impact of rapid climate change in the Arctic':

http://www.metoffice.gov.uk/media/pdf/p/i/HCTN_91.pdf

We note that the downward trend in Arctic sea-ice extent, taking account of the seasonal cycle, is now well-established from satellite observations since 1979 and has been reported as being statistically significant in the peer-reviewed scientific literature.

Given what we know about the amount of checking that doesn't go on in academic studies these days, particularly climate change, for policymakers to rely on the scientific literature is foolish in the extreme. In fact one could go so far as to characterise it as negligence.