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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Von Storch on the models again

In a post at Klimazwiebel, Von Storch and Zorita have expanded onf the views they put forward in the discusion paper I mentioned the other day.

We want here to set straight some misinterpretations that may have arisen in the blogosphere, e.g. Bishophill, and may also have been present in the review processes by Nature as well.

The main result is that climate models run under realistic scenarios (for the recent past) have some difficulty in simulating the observed trends of the last 15 years, and that are not able to simulate a continuing trend of the observed magnitude for a total of 20 years or more. This main result does not imply that the anthropogenic greenhouse gases have not been the most important cause for the warming observed during the second half of the 20th century. That greenhouse gases have been responsible for, at least, part or even most of the observed warming, is not only based on the results of climate simulations, but can be derived from basic physical principles, and thus it is not really debated. It is important to stress that there is to date no realistic alternative explanation for the warming observed in the last 50 years. The effect of greenhouse gases is not only in the trend in global mean near-surface temperature, but has been also identified in the spatial pattern of the observed warming and in other variables, such as stratospheric temperature, sea-level pressure and others.

Although von Storch and Zorita talk of misinterpretations, I'm not sure there is any great difference between what they say here and what I concluded last week. At the time I said that the models are falsified - they run too hot. A model that had a slower rate of warming would not be. So a claim that part of the observed warming is anthropogenic is still scientifically tenable. How big a part is manmade is, given the failure of the models, anyone's guess.

I'm not, however, convinced that the only plausible explanation for the warming of the last 50 years is greenhouse gases. As I mentioned the other day, the IPCC looks set to conclude that there was a Medieval Warm Period. Last time I heard Rob Wilson discuss the matter, he said that the climate models couldn't even get the MWP in the right historical position, let alone explain its apparently large magnitude.

So once again I find myself returning to the point I make so often. The unknown unknowns are a big problem. Scientists would do themselves a favour if they recognised it.

[Comments will be tightly edited for relevance and tone]

The missing tropical hotspot

Climate Dialogue has another of its learned coffee mornings up and running, this time examining the missing tropical hotspot in the troposphere. In it we learn from Carl Mears that

...the tropospheric hotspot is often presented as some sort of lynchpin of global warming theory. It is not. It is just a feature of a close-to-unstable moist atmosphere.

Now this is pretty surprising to me. If I recall correctly, the tropospheric hotspot was behind the big story of the IPCC's Second Assessment Report, the "discernable influence" of mankind on the climate; his fingerprints left all over the scene of the crime.

This is all rather reminscent of the Hockey Stick, which everyone now agrees is peripheral to the global warming hypothesis, but was nevertheless promoted by the IPCC as if it meant something.

Von Storch: models are falsified

Roddy Campbell points us to this discussion paper by Hans von Storch et al, which looks at the divergence between climate models and observations:

In recent years, the increase in near-surface global annual mean temperatures has emerged as considerably smaller than many had expected. We investigate whether this can be explained by contemporary climate change scenarios. In contrast to earlier analyses for a ten-year period that indicated consistency between models and observations at the 5% confidence level, we find that the continued warming stagnation over fifteen years, from 1998 -2012, is no longer consistent with model projections even at the 2% confidence level. Of the possible causes of the inconsistency, the underestimation of internal natural climate variability on decadal time scales is a plausible candidate, but the influence of unaccounted external forcing factors or an overestimation of the model sensitivity to elevated greenhouse gas concentrations cannot be ruled out. The first cause would have little impact of the expectations of longer term anthropogenic climate change, but the second and particularly the third would.

That seems quite important to me. Note also that "the heat's all in the deep oceans" doesn't seem to be on the table as an explanation.

Akasofu's model

In recent months there has been a lot of attention devoted to the failure of the GCMs to predict the pause/standstill/hiatus in temperature rise seen for the last decade or more. Mike Kelly points me to this recent paper in the open access journal Climate. It's by the prominent sceptic Syun-Ichi Akasofu, whose naive model of global temperature change gets attention every few years.

The model essentially superimposes a multidecadal oscillation on an upward linear trend representing the recovery from the little ice age, and it gets attention because it performs so well. In the latest paper, the model is compared to observations for the period to 2012.

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The validity of climate models: a bibliography

A reader sent me some correspondence he had received from the Met Office. He had been enquiring about what evidence Prof Slingo et al had of the validity of the output of GCMs, and received in return the following bibliography:

Airey MJ, Hulme M, Johns TC (1996) Evaluation of simulations of terrestrial precipitation in UK Met Office/Hadley Centre climate change experiments. Geophysical Research Letters 23:1657-1660

Allan RP, Ramaswamy V, Slingo A (2002) Diagnostic analysis of atmospheric moisture and clear-sky radiative feedback in the Hadley Centre and Geophysical Fluid Dynamics Laboratory (GFDL) climate models. Journal of Geophysical Research-Atmospheres 107:7

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Science Media Centre spins the pause

The Science Media Centre is best known to readers here for its press release about the Oxburgh inquiry, in which they managed to quote only scientists implicated in wrongdoing over Climategate.

Today the centre has released a statement on the failure of global temperatures to rise in line with the models. It can be seen here.

It's spin of course, although perhaps not quite as blatant as we are used to from Fiona Fox et al. As one might expect there's a lot of emphasis on natural variability and not a lot on why the observations are on the cusp of falling out of the uncertainty bands. Lots of "our understanding is getting better" and not a lot of "nobody has a clue what's going on".

There's a complete misrepresentation of science's level of understanding of the reasons why this is happening:

It is becoming increasingly clear that absorption of heat in deep oceans is part of the explanation.

I think what they mean is that this is a somewhat implausible post-hoc rationalisation of the failure of the models to conform to reality; perhaps the copyeditor missed it.

As I said in Parliament, the inability of climate scientists to admit their ignorance is one of the reasons nobody trusts them. The Science Media Centre are just helping that process along in the wrong direction.

Update on Jul 22, 2013 by Bishop Hill

Lucia tweets out that the SMC's remarks about climate sensitivity make no sense:

"we are becoming more confident of mid-range figures." why not 'mid-range or lower?

Update on Jul 22, 2013 by Bishop Hill

David Shukman's take is here.

...the scientists say, pauses in warming were always to be expected. This is new - at least to me.

It is common sense that climate change would not happen in a neat, linear away but instead in fits and starts.

But I've never heard leading researchers mention the possibility before.

Low-sensitivity model outperforms

Steve McIntyre has a must-read post about a low-sensitivity climate model which, when loaded up with actual greenhouse gas levels, completely outperforms the Met Office's HADGEM2.

Ducking, diving, dodging, weaving

There was an interesting written answer in the House of Lords yesterday, with Baroness Verma singularly failing to answer a question about falsifying climate models.

Lord Donoughue (Labour): To ask Her Majesty’s Government whether the Met Office has set a date by which, in the event of no further increase in global temperatures, it would reassess the validity of its general circulation models.

Baroness Verma (Whip, House of Lords; Conservative): General circulation models developed by the Met Office are continually reassessed against observations and compared against international climate models through workshops and peer reviewed publications. The validity of general circulation modelling has been established for over four decades, as evident in the peer-reviewed literature. Such models are further developed in light of improvements in scientific understanding of the climate system and technical advances in computing capability.

Short term fluctuations in global temperature do not invalidate general circulation models, or determine timelines for model development. The long term projection remains that the underlying warming trend will continue in response to continuing increases in atmospheric concentrations of greenhouse gases.

It was Baroness Verma who was on the receiving end of Lord Donoughue's questions on surface temperature trends, and her ability to duck, dive, dodge and weave, often at the same time, was something to behold. It was many, many weeks before Lord D was able to pin her down to an answer.

Here we go again.

Von Storch on the pause

Hans von Storch, interviewed in Spiegel, is well worth a read this morning:

Unfortunately, some scientists behave like preachers, delivering sermons to people. What this approach ignores is the fact that there are many threats in our world that must be weighed against one another. If I'm driving my car and find myself speeding toward an obstacle, I can't simple yank the wheel to the side without first checking to see if I'll instead be driving straight into a crowd of people. Climate researchers cannot and should not take this process of weighing different factors out of the hands of politics and society.

Brown out

Robert G. Brown (rgbatduke) has posted another devastating comment at WUWT, which I am again taking the liberty of reproducing in full here. For the counter-view, see Matt Briggs here.

Sorry, I missed the reposting of my comment. First of all, let me apologize for the typos and so on. Second, to address Nick Stokes in particular (again) and put it on the record in this discussion as well, the AR4 Summary for Policy Makers does exactly what I discuss above. Figure 1.4 in the unpublished AR5 appears poised to do exactly the same thing once again, turn an average of ensemble results, and standard deviations of the ensemble average into explicit predictions for policy makers regarding probable ranges of warming under various emission scenarios.

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The Economist continues to waver

The Economist's coverage of the climate sensitivity issue was the start of a huge change in the attitude of the mainstream media to the idea that maybe climate change was not quite the problem it was cracked up to be. So it will be interesting to see what the dailies make of the latest offering from that august journal:

The reality is that the already meagre prospects of these policies, in America at least, will be devastated if temperatures do fall outside the lower bound of the projections that environmentalists have used to create a panicked sense of emergency. Whether or not dramatic climate-policy interventions remain advisable, they will become harder, if not impossible, to sell to the public, which will feel, not unreasonably, that the scientific and media establishment has cried wolf.

...if the consensus climate models turn out to be falsified just a few years later, average temperature having remained at levels not even admitted to be have been physically possible, the authority of consensus will have been exposed as rather weak.

This isn't a crisis for climate science. This is just the way science goes. But it is a crisis for climate-policy advocates who based their arguments on the authority of scientific consensus.

Some model thoughts

There have been a few interesting bits and pieces floating round on the subject of climate models in recent days.

At WUWT, Bob Tisdale has reviewed the CMIP5 model predictions of Antarctic sea ice and found that they have performed no better than their predecessors.

Judith Curry has focused on a paper by Stevens and Bony that looks at one of the fundamental deficiencies of climate models - their inability to represent clouds - and considers the futility of trying to add complexity in other areas until this basic failing has been overcome.

And then Doug McNeall tweeted the following remarks in defence of the CMIP5 ensemble:

The CMIP5 ensemble is not set up a a calibrated probabilistic prediction system: it doesn't pretend to be one either.

It is just a set of plausible trajectories that the climate might take, given a certain set of forcings.

They're not predictions - just plausible outcomes, and those outcomes have not been borne out in practice. The models have fundamental deficiencies too.

Do the policymakers discussing the Energy Bill in Parliament today understand these issues?

An odd coupling

Reader Jelle U. Hielkema left an interesting comment about Aubrey Meyer's evidence to the Environmental Audit Committee last week. Meyer has accused the Met Office of deliberately misleading the committee in earlier evidence:

[Y]ou asked me to summarise the key points in Aubrey's work. I am assuming you mean on the matter of ‘contempt for the house‘. To do this you need to look at Aubrey’s *written evidence* to the EAC particularly on pages 19 and 20. It is here: -http://www.gci.org.uk/Documents/EAC_Real_.pdf

The key point in this is the *p

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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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