The Austrian Alpine Club (Sektion Brittania) runs an annual photo competition. I’ve finally got round to entering some of my summer pix; see here. Here’s my favourite that I didn’t enter; this was part of Stubai: Wilder Freiger by the Lubeckerweg.
I can thoroughly recommend the reviews. But this post, as I’m sure you’ve already guessed, is not about common problems with perforce but about ScienceBlogs. Or National Geographic blogs, I’m never quite sure what “we” are nowadays.
But nonetheless I was surprised by Sb Has 19 Active Blogs (of which I’m one, of course, though not as active as I used to be). Which in turn points me at The Life and Death of Blog Networks. FWIW, I am enjoying the benign neglect and have nothing to complain about.
On a happier note, Elon Musk Names SpaceX Drone Ships in Honor of Iain M. Banks – Just Read the Instructions and Of Course I Still Love You although saying why was a bit naff of him.
Meanwhile, if you’re interested in small boats, here’s Paul Holland and I in a pair for the winter Head to Head. I’m the one you can’t see 🙂
Or so says Gavin in How Climate Change Denial Still Gets Published in Peer-Reviewed Journals via Retraction Watch. Dountless Monkers will welcome yet another chance to bluster and threaten to sue1. The paper has been “harshly criticized by physicists” (who knew ATTP was plural, eh?) and “climate scientists” though to be fair ATTP only really skimmed it for errors, and RT just pointed out that the palaeo bits were a bit crap.
[Update: I’ve just noticed what I should have seen immeadiately: a fatal flaw in Gavin’s words that totally vitiates his argument: it should be et al. not et. al. Obvs. Another good English boy gone to bad over in the land of the illiterate.]
I was conversing with a friend who would probably rather be nameless, and I said
I confess, I didn’t even bother reading it, or even the few blog posts that have mentioned it, because it seemed so obviously drivel. We expect no less from M’Lord. I’d also assumed that it was *uninteresting* drivel – do let me know if I’m wrong about that.
To which I got the reply “I’m not sure it’s coherent enough to count as drivel. There’s quite a bit where I had no hope of working out what it means or what the point of saying it was.” Anyway, you get the idea: we were competing to be as disrespectful as we possibly could, even if we didn’t give it its due – which would have been to ignore it. But, alas, my friend also gave some insight into what was wrong with it, which I’ll share with you. In the spirit of showing contempt for the paper, however, I must point out that I haven’t actually thought about this very hard, and I still haven’t read the paper. Also, these aren’t his exact words.
The flaw that underlies most of it is that the r_t in the equation ATTP quotes is taken from Roe et al. applying a step change in CO2 to a 1D model. A standard one, though of course there are a range of responses; anyone competent would consider this. At one point MSLB do say their r_t is observed, but that’s a page or so after they correctly describes its origin (consistency from page to page is not this paper’s strong point). So it is a Green’s function that needs to be convolved with the forcing history but MSLB multiplies them, and then tickles a weasel. Naturally, 164 years after their start year of 1860, we must be so near equilibrium with all the CO2 in the atmosphere that the remaining warming is a tiny fraction of the warming so far, as they calculate precisely.
Well, there you have it. Discuss.
Update: there’s also Monckton, Soon, Legates, and Briggs falsely claim to have presented a new climate model by Jan P Perlwitz [archive]. Thanks to ATTP for the link. Don’t miss the appearance of Scrotum. [Comments there are good. Its complex at first, but by about Bode Monkers has made it clear that like so many others of his ilk he (a) hasn’t got a clue how the GCMs are built, and (b) thinks the CS is built in.]
There’s more analysis in a comment at JP’s by tilting@windmills.
And The Monckton equation by apsmith.
And With climate models, simpler isn’t necessarily better – Grantham Institute Co-Director Professor Joanna Haigh. Note how Monkers, in the comments, praises Alexandra Cheung for her thoughtful critique, having failed to realise that the words are JH’s, merely posted by AC.
Vaguely on topic – the topic being the reputation of the journal that MSLB published in (which is the little-known “Science Bulletin”, formerly the “Chinese Science Bulletin”. It seems very arrogant, to me, for them to so rename their journal, especially if they’re not even going to publish science in it); going off to the far side of the world does seem rather odd, when you could be publishing in Pattern Recognition in Physics right at home – we have Did A Romanian Researcher Successfully Game Google Scholar to Raise his Citation Count? – thought I should say that I have no reasons to think that MSLB have done this. Read the post, and the update at the end.
Update: furtively anonymous paid thermo-Fascist troll
furtively anonymous paid thermo-Fascist troll
James Rowlatt (who is, it appears, the only person being paid to post to the thread, being apparently an employee of Monkers and has been for a while):
It seems to me, on reviewing this thread, that Lord Monckton has been exemplary in his courteous replies
Well, naturally enough, your paid employees will judge you kindly. Its a touch odd that JR doesn’t explicitly disclose that he is being paid to post; you’d kinda expect that he would, were he being good.
1. Well, that didn’t take long:
In view of the libels in the Carbon Brief piece, I shall be asking my lawyers whether they recommend insisting that it carry a response from me. If not, I shall put it in a national newspaper, where it will reach a far larger audience than the Carbon Brief, subsidized though it is by a shady foundation.
Shamelessly stolen from ATTP’s “More than half” is the same as “> 50%”!, but I think this captures brilliantly a typical argument with the “skeptics”:
TPP has a link to the interesting story of Alfred Russel Wallace‘s bet with the flat-earthers that the Earth was, in fact, not flat. Somehow, that seems relevant.
Moyhu also has a nice pic, which I’ve inlined below, and a nice discussion of the different sorts of uncertainties.
At the same time, Muslims should acknowledge that they have not constructed the logical and theoretical framework within which extremism can be rejected formally. If anything, the opposite has happened in the last century, with increasingly literalist attitudes gaining strength for political reasons. And that is the core problem: A literal reading of even moderate Muslim beliefs can, and does, lead to behaviors incompatible with modern society. Like Christians, Jews, Hindus and others, Muslims have to turn towards a less literal, more inspirational and humanistic reading of their sacred traditions, drawing from them principles that can stand the test of time rather than literal, ahistorical prescriptions.
The hellish monotony of 25 years of IPCC climate change warnings from the Graun (thanks a); or, if you prefer, The Onion also covers it. And if you haven’t signed up you can get the tasteful message unlimited access for our foreign readers can be purchased for only $0.99 for the first month: That’s less than a dollar – approximately one day’s wages in most non-American countries!.
While we’re on totally crap “predictions” and extrapolations that are impermissible:
Nice, huh? As ever for these things, Timmy has the details.
* The specialist in causing pain – The Renaissance Mathematicus on yet another person – this time its Michael Vagg on The Conversation – getting Galileo wrong
* Historian joke
* Swiss bank to charge clients to hold cash
Its been a bit quiet around here. Don’t fear: a whole variety of things have wound me up recently, not least my colleagues inability to use perforce competently1. But none of them quite rose to the level of bothering to post. I was going to write something gratuitously offensive about the Charlie Hebdo stuff, but it seems like everyone is appropriating it to their own cause, so I won’t. Though I did think that it was wittily transgressive, in a post ostensibly defending free speech, to snip comments purely because they offended the diva.
But this post is about How much is climate change going to cost us? by David Roberts, which appeared on my FB feed. Or rather, its about Temperature impacts on economic growth warrant stringent mitigation policy3 by Moore and Diaz, Nature Climate Change (2015) doi:10.1038/nclimate2481. This is, perhaps somewhat contrary to my initial impressions and prejudices (and my irritation with parts of DR’s write-up), quite a decent paper (caveat: IANAE). Unlike the press release which is, as you’d expect, appallingly un-nuanced, saying “We estimate that the social cost of carbon is not $37 per ton, as previously estimated, but $220 per ton,” said study coauthor Frances Moore. Its perfectly clear from the paper itself that uncertainties prevent any statement this definite. That paper, itself, is heavily reliant on Temperature Shocks and Economic Growth: Evidence from the Last Half Century by Dell, Jones and Olken (Moore and Diaz, in the academically approved fashion, lard their paper with many references; but the vital numbers come from Dell et al.). This last paper (we’re at the bottom of the stack now, fear not) contains lots of words and many numbers; naturally, I only skimmed it. But figure 2 is very interesting:
As they say:
our estimates show large, negative effects of higher temperatures on growth, but only in poor countries. In poorer countries, we estimate that a 1◦ C rise in temperature in a given year reduced economic growth in that year by about 1.3 percentage points. In rich countries, changes in temperature do not have a robust, discernable effect on growth.
There’s also a strong relation between GDP and absolute temperature, which we’re all fairly familiar with. There’s an uncertainty of how to interpret that, for the future: does being rich make you more resistant to temperature “shocks”? M+D call that the “resilience mechanism”. I’d say yes. Or do we expect GW to push more countries into the poor-because-hot basket? M+D: “temperature mechanism”. I’d guess no. I’d also guess that temperature “shocks” are easiest to see in agriculture, and the richer you are the smaller a fraction of your wealth comes from ag.
Moore+Diaz put Dell’s numbers into a version of DICE (ah, I’ve glossed over the whole point there, haven’t I? Read Roberts if you like; the idea is to put effects that reduce growth rates into DICE-a-likes, rather than simple damage numbers), and discover that it makes bugger all difference to the rich world2, but reduces the poor world’s growth by 40% by 2100, based on some scenario or another.
Given that the rich world is massively richer than the poor world, I think that the wealth-weighted reaction to all that would be negligible, though I don’t have any numbers to demonstrate it.
Moore+Diaz consider the different effects that occur if you believe the “temperature mechanism” or the “resilience mechanism”. Unsurprisingly, it makes a huge difference. Browsing their figure 3, in 2080 its the difference between a social cost of carbon (SCC) of ~$1000 per ton, or a number too small to distinguish from zero on their scale.
Before ending, there’s one more picture I’ll show you from Moore+Diaz, because I don’t understand it:
This shows the effects, on emissions optimised “to maximise global discounted social welfare” (DICE-2R (red) is std DICE, I think; gro-DICE (blue) is their fudged version). As far as I can tell, they don’t explain what that is. I understand that their version is going to increase carbon costs, so blue lower than red for emissions makes sense. But given the (fairly low, in the std case) damage from warming, I don’t understand why emissions drop so much for std-DICE. Perhaps there are some assumptions in there that I don’t understand.
Anyway, there you go. Interesting stuff. Hopefully someone with more patience will read the papers more carefully and point out the bits I’ve missed.
1. Well, really, its more a fundamental understanding of version control than perforce; how changes propagate, why integrate -f is generally a bad idea, why being profligate with reverts is likewise unhelpful and doomed to cause pain.
2. There’s a small piece of dishonesty in M+D that the referees should have picked up: they’ve used a small negative value from Dell: as M+D say “smaller effects in rich countries”. But Dell really find no discernable effect at all; the correct value to use, based on that, for rich countries, is zero. Worse than that, if you look at the figure I’ve inlined, the effect is actually positive for rich countries. Quite how M+D turned that into a small negative I don’t know.
3. My access via DR to that paper in Nature comes with a “referrer_access_token”, so I think this is the all-new Nature sharing mechanism that JA was so scathing of. However, its worked for me, here.
* Enchanted Necromancer Brings Life Back To Once-Dead Argument – thanks Hank
* I Am Not Making This Up; Venezuela Bans Queues To Beat Product Shortages – Timmy in Forbes, demonstrating that its possibly to totally fuck up your economy without GW.
* More FB feed stuff: I may take this one on next: That Was Easy: In Just 60 Years, Neoliberal Capitalism Has Nearly Broken Planet Earth, featuring Transgressing a boundary increases the risk that…
None of the following are warranted in any way. I’m just clearing out some old emails and didn’t want to completely throw them away. This may be only of interest to me, and possibly not even me.
* Spock warns of coming ice age
* Slowing down as an early warning signal for abrupt climate change – Vasilis Dakos, Marten Scheffer, Egbert H. van Nes, Victor Brovkin, Vladimir Petoukhov and Hermann Held, PNAS, 2008.
* Significant contribution to climate warming from the permafrost carbon feedback Andrew H. MacDougall, Christopher A. Avis & Andrew J. Weaver – Nature, 2012.
*Claim of solar influence is on thin ice: are 11-year cycle solar minima associated with severe winters in Europe? – Geert Jan van Oldenborgh, Jos de Laat, Juerg Luterbacher, William Ingram and Tim Osborn, in Klimazwiebel. Note last para.
* Increases in greenhouse forcing inferred from the outgoing longwave radiation spectra of the Earth in 1970 and 1997 – John E. Harries, Helen E. Brindley, Pretty J. Sagoo & Richard J. Bantges; Nature 410, 355-357 (15 March 2001) | doi:10.1038/35066553.
* Adjustments in the forcing-feedback framework for understanding climate change – Steven C. Sherwood, Sandrine Bony, Olivier Boucher, Chris Bretherton, Piers M. Forster, Jonathan M. Gregory, Bjorn Stevens. BAMS http://dx.doi.org/10.1175/BAMS-D-13-00167.1.
* Law and Expediency – Bystander.
* Study of massive preprint archive hints at the geography of plagiarism
* Travels in the Alps Volume 2 Chapter 35 by Horace-Bénedict de Saussure.
Meanwhile, above the Franz Senn hut in Austria in September:
In my Where are they now? review of 2014, I unforgiveably forgot the sensation of the year, Force X from outer space. Its worth reviewing, because (a) its not quite dead yet (or perhaps more accurately its proprietors haven’t yet given up hope of revivifying it) and (b) the original played out for so long that most people lost track of the errors.
If you’ve no idea what this is about – and you care – or if you need a refresher, then its probably best to go off and read The Notch-Delay Solar Theory because that helpfully lists all the drivel in one place, rather than the smeared-out-over-months that the original got. If you think I’m being dishonest by biasing you by calling it “drivel” well, tough; look through their web page and you’ll see that they are less than honest in describing criticism of their work. Note, BTW, there’s a semi-dangling update at the end where it all went quiet, but ter be ‘onest wiv yer guv I’d lost interest in the details by then; Sou took that as the tombstone of the “theory” and it does seem to go rather quiet from there.
My criticism of all this is:
To simplify: DE has found that the spectrum of the global temperature signal (T) is consistent with simple red noise, when viewed broadly, over the timescales he is looking at; and this should be no surprise (but it is to him). He’s also found that the solar forcing spectrum (S) is also red noise, apart from the peak at 11 years. For reasons that are unclear, he has decided that S is forcing T (even though at other points he denies this assumption is build in, but it is), and therefore that the difference between the spectra represents the xfer function, and hence a notch filter. But another possibility is that S isn’t forcing T in any significant way. DE’s “force X” seems to me somewhat like the luminiferous aether – it only needs to exist if you try to impose your view on reality.
And I think that’s most other people’s view, too. Or at least, of anyone who bothered look at it in any detail. Few did. But, where did it go? It spawned a couple of posts here:
* the Bomb Plot – in order to try to make sense of their non-physical results, they ended up assigning a ridiculously high value to the atmospheric-bomb-test forcing. I found that there wasn’t a good source for what the actual forcing was (answer: its so small no-one cares). That was from their part VII, I think.
* Battle of the graphs – for no apparent reason, other than to demonstrate their ignorance, they decided to misattribute some faked up graph to IPCC ’95. Why they bothered I don’t know, because it didn’t help their argument. Still, its nice to be reminded that they’re wrong about the small things as well as the large.
But what about the rest of the world?
The sound of silence
Oh, you’ve guessed.
The response of the denial-o-sphere must have disappointed the Novaites, because it largely ignored their theory, as did the world at large. Lubos ripped it apart, then took his post down, then put his post back up, then did the hokey-cokey and who knows what. WUWT gave it a guest spot, but with the unusually explicit disclaimer There are still many unanswered questions about this model. I provide this essay for the purposes of discussion, but I give no pro or con endorsement. There’s little – oh, all right, no – intelligent discussion of the theory itself in the post or the comments, instead it fairly swiftly degenerates into an argument with Leif Svalgaard about TSI, and Willis Eschenbach complaining about them not releasing their data (broken by NikFromNYC suggesting “Anthony, just buy a gun. Point it at the center of your head. Don’t miss” which earns him a permaban, and the label of “warmist” from schitzree, tee hee). There was one more – A Cool Question, Answered? – found via Sou, who mocked it briefly – in which I make a gueat appearance as a Solar Denialist. I thought the D-word was banned at WUWT – perhaps not for People We Don’t Like.
I’m not dead yet!
In 2015 the hunt for clues continues…
which brings up the immediate retort: yes, you really are in desperate need of A Clue. But thinking about it more, I’m reminded about the notorious “search for clues” for the meaning of Justice in the Republic, I think it was. Anyway, that’s a despicable piece of propaganda masquerading as philosophy, which makes it a suitable cognate to the post.
Is there a lesson in all this?
Lots. The minor ones are stuff like: you really must stop paying any attention to the “skeptic” drivel, because life is too short. But what about lessons for them – making the admittedly unlikely assumption that they’d like to learn; and that they really are trying to do this “science” stuff and not just fill in the blog over the lonely summer months.
The major one is a variant on Feymann: The first principle is that you must not fool yourself — and you are the easiest person to fool. So you need someone to criticise your theory. People who read it and say “this is great” are useless, as are the people who don’t even read it but still say “this is great”. The “skeptics” have very few serious people they can talk to who can give them anything useful as feedback. As it happens, in this case, they did get a semi-usable answer from Lubos. But they didn’t like what he said, so ignored him. Which was silly (for them, in this case. In most cases one should, obviously, ignore everything Lubos says that is related to climate).
For details, I refer you to the “2015 update” of “Dr” Roy Spencer is sad and lonely and wrong.
* Soc Flop
This got mentioned in early 2014 at Planet3.0. To be fair to mt, he wasn’t really pushing the video itself, just using it to illustrate his point (which I think is uncertainty-is-not-your-friend; I agree with that), though he did call it “excellent”. But since, as I said in the comments there I don’t think its great video; I think its terrible, I wasn’t desperately happy. But, I shrugged and turned away. Now I see that Dana Nuccitelli is giving it space in the Graun, (and DA is linking to it, though possibly only because he likes the headline and sub), so I’ll repeat myself more publically. What I said, in full, was:
I don’t think its great video; I think its terrible.
Minorly, A / True doesn’t have a happy face – it still has an appalling financial meltdown (in his scenario).
But more importantly, he makes no attempt to assess the probability of B / True. So he’s trying to short-circuit, or evade, the cost-benefit analysis that needs to be done.
That wasn’t the question you asked in this post, of course.
[You need to know that A is “we took action on GW”, B is “we didn’t”. True is “GW turns out to be real”, False is “It was all a dream”.]
mt answers starting with “I think there is a point to what you say”, which is enough for me to excuse him, but not DN. Note that the assertion of the video (see around 1 min in) is that the argument contained therein means “we don’t need to know whether its true or not”.
Note that there’s a a trick: in A / Yes, he takes the extreme, for illustration, and gets global economic meltdown. In B / False, he says “since we granted the extreme in A / Yes, we should grant the extreme here too”. But they aren’t connected, except in both being very simplistic.
At 5:15 he asserts that if you add in the subtleties and intermediate cases, his conclusion (to come) still holds.
And that conclusion is that B / True (“GW is real and we took no action”) is so bad, that the best thing to do is avoid any possibility of “being in that column”. My answer to that is above. At P3, Walter Manny said Craven’s exercise is simply Pascal’s Wager and I don’t think he got a good answer.
To make the comparison clearer, I’ve scribbled on a still from the video. Wittily, that makes GW “God”. We can see its not quite Pascal’s wager. Conventionally, in PW, you assign a small positive to “no God, and no Belief” and a small negative to “no God, Belief” to reflect the life of sin that good Christians can’t enjoy; in this case, “no GW, Belief-aka-action” has substantial costs, but they are assumed small compared to the “Hell” square. Similarly, in PW the “God, Belief” square is infinitely positive, whereas here its actually worse than “no God, no belief” which is the best possible outcome, though we’re not supposed to believe in it. Indeed the comparison to PW is only that “God-aka-GW, no-belief-aka-no-action” is effectively infinitely bad in both.
The useful point about comparing it to PW, though, is that no-one believes in God because of it. So if the comparison is good (I think it is) you can assert “no-one will believe in action on GW just because of this grid”.
The good atheist assigns zero probability to “God exists”, and so zero probability to Hell, so that part becomes irrelevant in the calculations. The experienced denialist assigns zero probability to “GW will be catastrophic”, and so ignores that bit. I’m not an experienced denialist, so I’m not ignoring it, but I am downplaying it. Why? Mostly because i think we want to do something more sensible, which is to attempt a reason-based cost-benefit type analysis, which this isn’t. If forced to go further, I’d say that current best-guess is that GW won’t be an utter catastrophe; indeed, in economic terms (say, those of Stern which I think is on the high side) its perhaps (from memory) 10-20% of global GDP by 2100. To make it catastrophic – somewhere close to the infinity that is implied – you need to try much harder than Stern, and I think that’s unlikely (I also think that if starting looking that way, we’d probably have time to go into emergency mode (yes, despite the inertia of the pol/econ system, and our infrastructure base); a time-dependent element is necessary in the analysis, but lacking here. He makes a small comment in this direction at 7:20 – that we’ve recently learnt that the disaster could happen quickly, within a decade, so it affects us not our grandchildren; I don’t know what he means by that).
In case you’re wondering, no, I’m not arguing that the failure of the argument in the video means we should do nothing about GW. I’m only arguing that the failure of the argument in the video means it should have no (logical) consequences.
To paraphrase Einstein, you should reduce a problem to the simplest possible, but no simpler. This square reduces the problem past the minimum degree of simplicity that is useful.
As I said near the start, mt’s main argument around this point is uncertainty-is-not-your-friend; and I agree with that. There’s an essentially-sane take on that at The Conversation: Uncertainty isn’t cause for climate complacency – quite the opposite. But then again, it doesn’t reach the same conclusions as Greg Craven.
Good grief, you’re behind the times
It turns out that the video dates from 2007, duh. And Greg Craven wrote a book about the same idea in 2009. Which I haven’t read, but judging from reviews (treehugger, Simon Singh, Grist) it says much the same as the video. mt has a review at P3 that focusses on a completely different aspect of the book – how to know, to which the answer for most people is “trust”, which is correct, though its important to know how to know who to trust. But at that time, he doesn’t address what I (and the other reviewers) are taking as the book’s central argument.
There’s a wiki page. He even had a website about it, now apparently defunct. But via the wayback machine I can read http://www.gregcraven.org/en/the-book/endorsements-and-criticisms which points me at a response by “climate skeptic” (the wiki page used to ref this, but it got rm’d as non-RS).
I rally can’t endorse “climate skeptic” in general, because he links with approval to himself at coyote blog to show that feedbacks are probably negative, which says nothing useful but points to himself again. At that points he actually starts to say things, but they’re wrong (in a traditional-septic-but-not-actually-barking way, so I’ll spare you the details). And now I read it, I can’t really endorse his crit of the video, either, except in very general terms.
* Things I thought were obvious! – ATTP
* Is Climate Risk Systematically Understated? – asks mt at P3. Likely, yes.
* Taxonomy of climate/energy policy perspectives – essentially a rip-off of the same thing; from Curry
Oh good grief I hear you cry, not more science. Yes. Sorry. And its even about sea ice, but the Antarctic kind. This is in the trail of Holland and Kwok and so on.
Observations reveal an increase of Antarctic sea ice over the past three decades, yet global climate models tend to simulate a sea ice decrease for that period. Here we combine observations with model experiments (MPI-ESM) to investigate causes for this discrepancy and for the observed sea ice increase. Based on observations and atmospheric reanalysis, we show that on multidecadal time scales Antarctic sea ice changes are linked to intensified meridional winds that are caused by a zonally asymmetric lowering of the high-latitude surface pressure. In our simulations, this surface pressure lowering is a response to a combination of anthropogenic stratospheric ozone depletion and greenhouse gas increase. Combining these two lines of argument, we infer a possible anthropogenic influence on the observed sea ice changes. However, similar to other models, MPI-ESM simulates a surface-pressure response that is rather zonally symmetric, which explains why the simulated sea ice response differs from observations.
So, maybe the GCMs wind-pattern response, aka MSLP, around Antarctica is a bit off?
As an experiment, I thought I’d try posting some science instead of nonsense or mountains. From Nurture (Peter van der Sleen et al., Nature Geoscience 8, 24–28 (2015) doi:10.1038/ngeo2313):
The biomass of undisturbed tropical forests has likely increased in the past few decades1, 2, probably as a result of accelerated tree growth. Higher CO2 levels are expected to raise plant photosynthetic rates3 and enhance water-use efficiency4, that is, the ratio of carbon assimilation through photosynthesis to water loss through transpiration. However, there is no evidence that these physiological responses do indeed stimulate tree growth in tropical forests. Here we present measurements of stable carbon isotopes and growth rings in the wood of 1,100 trees from Bolivia, Cameroon and Thailand. Measurements of carbon isotope fractions in the wood indicate that intrinsic water-use efficiency in both understorey and canopy trees increased by 30–35% over the past 150 years as atmospheric CO2 concentrations increased. However, we found no evidence for the suggested concurrent acceleration of individual tree growth when analysing the width of growth rings. We conclude that the widespread assumption of a CO2-induced stimulation of tropical tree growth may not be valid.
This is a partial antidote to the CO2-is-plant-food people, but also to the ZOMG-crop-yields-are-falling people, since increased water efficiency is good. Mind you, not all plants are exactly the same, so it may not apply to the crops we care about in the circumstances we care about. Biology is complex, no?
Carbon cycle extremes during the 21st century in CMIP5 models: Future evolution and attribution to climatic drivers
While I’m here, Zscheischler et al., DOI: 10.1002/2014GL062409 is on a similar theme:
Climate extremes such as droughts and heat waves affect terrestrial ecosystems and may alter local carbon budgets. However, it still remains uncertain to what degree extreme impacts in the carbon cycle influence the carbon cycle-climate feedback both today and the near future. Here we analyze spatiotemporally contiguous negative extreme anomalies in gross primary production (GPP) and net ecosystem production (NEP) in model output of the Coupled Model Intercomparison Project Phase 5 (CMIP5) ensemble and investigate their future development and attribution to climatic drivers. We find that relative to the overall increase in global carbon uptake, negative extremes in GPP and NEP lose importance toward the end of the 21st century. This effect can be related to elevated CO2 concentrations and higher amounts of available water at the global scale, partially mitigating the impacts of droughts and heat waves, respectively. Overall, based on CMIP5 models, we hypothesize that terrestrial ecosystems might be more resilient against future climate extremes than previously thought. Future work will have to further scrutinize these results considering that various biological and biogeochemical feedbacks are not yet integrated within Earth system models.
And to complete the trilogy, one including our very own William Ingram:
Correcting precipitation feature location in general circulation models
There is much evidence that precipitation responses to global warming involve wet regions becoming wetter and dry regions drier. This presents challenges for the interpretation of projections from general circulation models (GCMs) which have substantial biases in the location of precipitation features. While improving GCM simulated precipitation is the most desirable solution, adaptation and mitigation decisions must be made with the models already available. Many techniques have been developed to correct biases in grid point precipitation intensities, but few have been introduced to correct for location biases. Here, we describe a new technique for correcting the spatial and seasonal location of climatological precipitation features. We design this technique to respect the geometry of the problem (spherical spatial dimensions, with cyclic seasons), while conserving either precipitation intensities, or integrated precipitation amount. We discuss the mathematical basis of the technique and investigate its behaviour in different regimes. We find that the resulting warps depend smoothly on the most influential parameter, which determines the balance between smoothness and closeness of fit. We show that the technique is capable of removing more than half the RMS error in a model’s climatology, obtaining consistently better results when conserving integrated precipitation. To demonstrate the ability of the new technique to improve simulated precipitation changes, we apply our transformations to historical anomalies and show that RMS error is reduced relative to GPCP’s anomalies by approximately 10% for both types of warp. This verifies that errors in precipitation changes can be reduced by correcting underlying location errors in a GCM’s climatology.
I don’t really approve of correcting the models, though.