Can we trust climate models?

Our latest paper, Can we trust climate models? has just appeared on the Wiley website (open access thanks to our Japanese friends who paid for this). To save a click, here's the abstract:

What are the predictions of climate models, should we believe them, and are they falsifiable? Probably the most iconic and influential result arising from climate models is the prediction that, dependent on the rate of increase of CO₂ emissions, global and annual mean temperature will rise by around 2–4°C over the 21st century. We argue that this result is indeed credible, as are the supplementary predictions that the land will on average warm by around 50% more than the oceans, high latitudes more than the tropics, and that the hydrological cycle will generally intensify. Beyond these and similar broad statements, however, we presently find little evidence of trustworthy predictions at fine spatial scale and annual to decadal timescale from climate models.

The paper was invited by the editors some time ago, under a slightly different title but they didn't object to us changing this to something that we felt matched the content a little better. The original plan was for two papers to appear together, with the other one written by a prominent sceptic. However, this seems to have fallen by the wayside. Although we could probably have guessed what they were likely to write, we didn't really want to take part in a direct debate, so rather than aguing against straw man criticisms we just tried to set out our own ideas. Given how it turned out I'm glad we did this! Writing this paper also fitted in well to our personal plans, as we had already pretty much decided at that time to leave Japan, and this gave us a good opportunity to summarise and review some work (including our own) when we weren't really minded to embark on a big new ambitious plan of research. I don't think our argument is likely to be considered controversial - perhaps some might think we are a little pessimistic about the regional performance of models (by which we basically mean anything less than hemispheric) but our recent work with paleoclimate really has brought home to us that they don't get much right about patterns on this sort of scale, even for temperature still less precipitation.

The reviewers made some helpful comments, perhaps the only real criticism was that we sounded like a bland consensus and weren't really making an opinionated statement as might be hoped for in an "opinion" article. But we wanted to say what we thought was correct and justified (ie, a true summary of our opinions), rather than being artificially controversial. I'll be very happy if the paper is seen as a useful summary of how much we can trust climate models, and why.

[jules' pics] Fermentation

It's most important thing in Belgium.


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Posted By Blogger to jules' pics at 5/29/2014 06:15:00 AM

BlueSkiesResearch.org.uk: PMIP3

BlueSkiesResearch.org.uk

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PMIP3 Posted: 28 May 2014 03:43 PM PDT PMIP, the paleoclimate modelling inter-comparison project used to be an organisation that set up the protocols for a handful of climate models to run two time intervals from the past – 21ka BP and 6ka BP. Now there are many time intervals, transient experiments, a whole host of cross cutting “working groups”, but unfortunately still only a handful of models involved. It isn’t clear to me where it should go next, but It is certainly all quite exhausting, especially when coupled with the ridiculously high alcohol tolerance of the Belgians. The afternoon of official fun was today, from 2-11pm, and those of us of slighter build were pretty much defeated by 3pm. Germans and Dutch drink beer, French wine, but the Belgians can’t decide and drink twice as much of both, with the nuance that their beer is the strength of wine, amd their wine also the strength of wine.

Bengtsson burns his boats?

The popcorn-sellers will have been firing up their poppers over recent days. I was surprised by Lennart Bengtsson's announcement that he was joining GWPF, as I'd vaguely thought of him as a fairly mainstream climate scientist albeit slightly sceptical of model performance (as are many). Actually, on checking my library of downloaded papers, I find I only have one (out of more than 2000 in total) on which he's an author. But that may just be a function of focussing on different areas. He certainly played a significant role in years gone by as his Alfred Wegener citation says. While looking up his recent publications, I did come across "Why is the global warming proceeding much slower than expected?" but it's rather less sceptic-friendly than the title suggests, and I think it's widely accepted that (at least some) reanalysis products are not good at reproducing long-term trends, due to changes in observing systems (maybe Bengtsson was the first to say this? I dunno).

Anyway, not knowing the person, I shrugged and filed under "ignore", until he abruptly resigned, citing a storm of criticism and a whole one scientist (maybe more, reports are unclear) withdrawing from a joint paper. Well, it's odd that having chosen to take what he must have known would be a highly visible and politically significant position, he was so quick to shrink away from any reaction to it. I have to say I'm not particularly perturbed by some scientists writing to Bengtsson to express their views. If I'd known him, I might at least have checked that he really knew what he was getting himself into, as it's an unlikely step for any sensible climate scientist to take. I wonder what he expected people to say?

Now "someone" has planted a story in the Times, which coincidentally also appears on the GWPF site, about how Bengtsson once had a paper had a paper rejected by ERL. I wonder how such a non-story made the front page? I'm glad to see the editors have robustly defended themselves, and the full review certainly does paint a rather different picture of the quality of the research. It's funny to see that once the full text of the review was made public (rather than the very selective quotes in the Times). Bengtsson himself was quick to row back from what the article says.

Well, it's all good knockabout stuff. If I was looking for conspiracy theories here, I'd be curious as to the timing of all of this, drowning out as it has done the recent embarrassing U-turn on the part of the GWPF. Originally claiming to be an educational charity, its misinformation and campaigning have hardly been compatible with this and have resulted in numerous complaints to the Charities Commission. Following the CC's scathing comments "We advised the trustees that we did not consider that all the contents of the website advanced education, as required of a charity", they are splitting into the GWPF and GWPF. The GWPF now will really become an educational charity in line with its original claimed mission, honest gov, and the GWPF will be an independent campaigning group, that will presumably churn out the misinformation that the GWPF is no longer going to spout, without the awkward need to pretend it is truthful. I'm sure that there will be no chance of any confusion between the future squeaky clean GWPF and the wholly independent campaign group GWPF.

Perhaps Lennart Bengtsson simply couldn't decide which GWPF he wished to join. Either way, I don't think he's enhanced his reputation over this little debacle.

[jules' pics] Industry

Well, now I have veered towards the topics of politix and planning, I may as well carry on...

One of the wonderful things about being back in the UK is the incredible opportunity to get ones knickers in a twist about other people building things. In Japan you .just. .let. .go. (and say "shouganai", nothing can be done), because... Nothing Can Be Done - the yakuza are in charge of all the building operations. However, astonishingly, British people are permitted to feel responsibility for their own environment, and thus they must spend quite a lot of their energy getting excited about it.

The thing I have noticed most on return to the UK, is that people have started to plant windmills instead of trees.

This is particularly popular in Scotland, which seems determined to desecrate its beautiful landscape with them. It is a shame they don't produce more power, but I suppose they are less polluting in terms of actual poison than coal fired stations, and perhaps one can chop them down at a later date without too much difficulty. Most people I have spoken to can't understand why they get planted in the nice parts of the country, out of the view of people in cities. Personally I think they should be mass planted along the banks of all the motorways, since they are already massive blights on the landscape. However, I have to admit I cheered quite loudly when I spotted the large array in the sea off the Dee estuary (near Liverpool). I'm not sure we can complain too loudly - the Industrial Revolution started right here - it's all our fault - so surely our duty to endure the windmills as reminders of the sins of our ancestors.

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Posted By Blogger to jules' pics at 5/13/2014 10:38:00 AM

A sensitive subject

I know I said previously that I wasn't keen on participating in a ClimateDialogue on climate sensitivity, but the organisers recently repeated their invitation with a rather more interesting and relevant (IMO) group of participants. So this time I agreed to take part (it's also timed less inconveniently, though last week I was busy so my initial comments on the other blogs are rather brief). The blogs are now up, and comments about the technical content are probably better directed there. Accusations of hypocrisy (or worse) are welcome here, however :-)

[jules' pics] Seaside

Apparently this, above, is Jock's nose. It is located near St Abbs on the SE coast of Scotland. I am not sure where the rest of Jock is. Whether he is in England or Scotland could become a matter of great importance later in the year, when Scotland votes on whether to leave the UK.
The father and sister in law admiring the view. The sister in law is just back from near death experiences in Antarctica so she was happy to see, through her binoculars, the penguins nesting on the red cliffs over yonder.
(Actually they were guillemots).
Finally another property question. Is it just our NIMBYism, or does one of these houses look a bit out of place?
Hint: it can be yours for just 1.5Million UKP.

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Posted By Blogger to jules' pics at 5/10/2014 08:21:00 PM

Oh Vienna

We missed the EGU this year for a number of reasons, many of which are obvious enough. It's hardly necessary to go each year, research updates tend to be somewhat incremental and minor on that time scale. We were thinking we would probably go next year anyway, but a nice coincidence of dates has sealed the deal. The 2015 EGU general assembly has been announced as running from 12-17 April (the Sunday is just registration) and the Vienna City Marathon is on the morning of the 12th. When we were last there, we watched the marathon and thought it would be a fun one to do but they don't always fit together so well (like this year in fact). So our entries are in - jules for the half marathon, me for the full thing - and I look forward to making the most of a week of schnitzel, knödel, and breakfast buffets to recuperate with. Oh, and snoozing gently in lecture rooms. I wonder how many other geoscientists will be tempted to take part?

[jules' pics] Garden Birds

Despite the Sparrowhawk, little birds continue to risk life and limb to visit our bird feeders.


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Posted By Blogger to jules' pics at 5/03/2014 05:04:00 PM