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Comments 87951 to 88000:

87951. Albatross at 04:15 AM on 19 April 2011
       More Carbon Dioxide is not necessarily good for plants.
       JohnD @128, Yes, BP did grab those section titles from the paper-- but he did not provide full context and did not draw people's attention to the other key (negative) findings made by the authors. It is unfortunate that that BP and now you intent on not being true to the primary conclusions of the paper. They are optimistic only if they can figure out why the plants are not responding favourably to elevated CO2 levels-- maybe b/c they have not had time to adapt to those levels to take advantage...who knows...they don't seem to know. I could be wrong, but I think that you would be hard pressed o find a lead author on the paper who thinks that continuing wit BAU is acceptable in view of the evidence. Again, not all the lessons point to a negative outcome (that is also stated in the IPCC), at least when viewed individually, but this paragraph from the paper under discussion should be cause for concern for those who are prudent and risk averse: "More broadly, the stimulation of seed yield in response to growth in elevated [CO2] is ∼50% lower in FACE experiments than in enclosure studies for the world's four most important crops (Long et al., 2006; Ainsworth, 2008; Ainsworth et al., 2008a)." Now let us look at some of Dr. Leakey's earlier work: SP Long, EA Ainsworth, ADB Leakey, J Nosberger & DR Ort (2006) Food for thought: Lower than expected crop yield stimulation with rising carbon dioxide concentrations. Science 312:1918-1921 ADB Leakey, M Uribelarrea, EA Ainsworth, SL Naidu, A Rogers, DR Ort & SP Long (2006) Photosynthesis, productivity and yield of Zea mays are not affected by open-air elevation of CO2 concentration in the absence of drought. Plant Physiology 140:779-790 Again, the prudent path here is to prepare for the worst rathe than wishful thinking that we can overcome the problems identified in the FACE experiments. And that means reducing GHG emissions. Sorry, but BP has scored quite the own goal, and your post is not helping him. It is not clear to me that the FACE experiments considered heat stress. I found no specific reference to the impact of heat stress in the body text.
87952. KR at 04:09 AM on 19 April 2011
       More Carbon Dioxide is not necessarily good for plants.
       johnd - I completely agree, it's well worth reading the literature. Reading this particular paper, I was struck by statements such as: "A comparison of wheat yields from five different crop models with FACE results showed that the mean response ratio to elevated [CO2] was overestimated by more than a factor of two in the model projections .... Thus model parameterization and validation with summary data from FACE and non-FACE studies show that the quantitative differences in how crops respond to CO2 in the field compared to in chambers has important consequences for global food supply projections. Equally FACE has revealed factors operating in the open field situation that were not or cannot be identified by chamber experiments, for example, increased herbivory and performance of herbivore populations .... Most important though will be understanding why our major food crops fail to achieve the improved production under elevated [CO2] that can be achieved in protected environments and by some non-crop species." Emphasis added, references (in original) snipped for space issues and because I didn't want to copy their bibliography. FACE experiments are very useful - sadly, what they are revealing is that the skeptical predictions of greatly increased crop yields do not hold up under real conditions of CO2 increase, let alone accompanying heat stress and hydrology changes that will be factors as well.
87953. Alexandre at 04:01 AM on 19 April 2011
       Christy Crock #4: Do the observations match the models?
       This suggests the IPCC is consistently biased towards a conservative projection, leading to observable consistent errors. I think that's enough reason to rethink this policy.
87954. Bob Lacatena at 03:54 AM on 19 April 2011
       More Carbon Dioxide is not necessarily good for plants.
       125, Albatross, So according to BP, one study growing two species of trees in glass domes shows that trees are going to love the new CO₂ age. On the other hand, a huge swath of the Amazon is dying right before our eyes. Gee. I wonder what I should believe.
       Moderator Response: (DB) Perhaps wise investors should place their money in glass dome manufacturing plants.
87955. johnd at 03:41 AM on 19 April 2011
       More Carbon Dioxide is not necessarily good for plants.
       I think it needs to be pointed out that the paper Berényi Péter at 21:23 PM was commenting on, Journal of Experimental Botany (2009) 60 (10): 2859-2876. doi: 10.1093/jxb/erp096 is one of the papers Chris S at 19:54 PM recommended as a must-read paper about the FACE experiments, Journal of Experimental Botany http://jxb.oxfordjournals.org/content/early/2009/04/28/jxb.erp096.full Apparently apart from myself and BP few others have bothered to read any of those recommended, otherwise they would know that the points made by BP were taken directly from the paper referred to including point 6, which he specifically commented on. Point 6 also confirms a point I made earlier, as well as often previously, about how FACE trials are the only means by which modeling based on laboratory enclosure experiments are able to be assessed for the first time in real world open air field conditions. It seems that in most cases, as already elaborated on, the modeling generally fails to predict the actual outcomes, and thus, before they, the models, can be relied on to provide any useful predictions as to what might happen under future real world conditions, they need to be able to first accurately predict the outcomes of FACE trials. Indeed, this is one of the main purposes of the FACE trials, but many casual observers seem ignorant of this aspect. I think this should also be kept in mind whenever modeled projections are discussed, until they are confirmed by observations in the real world, they are at best only theories based on opinions. Overall the paper supports arguments generally made by many sceptics, but it first needs to be read throughly by those capable of absorbing and understanding the contents, or at least holding some small knowledge of the subject under discussion, but therein lies the problem.
87956. Albatross at 03:37 AM on 19 April 2011
       Christy Crock #4: Do the observations match the models?
       Thanks Dikran :)
87957. Philippe Chantreau at 03:35 AM on 19 April 2011
       More Carbon Dioxide is not necessarily good for plants.
       BP: "a bit less" Author: "much lower" Good idea to look at that paper, indeed.
87958. muoncounter at 03:30 AM on 19 April 2011
       More Carbon Dioxide is not necessarily good for plants.
       Albatross#125: "Talk about a positive feedback!" Here's another: Texas Co-ops Threatened by Wildfires. In an interesting ironic twist, the governor who wants to do away with environmental protection and has threatened to secede now is crying for federal protection: A Major Disaster Declaration makes the state eligible for response and recovery assistance from the federal government.
87959. Composer99 at 03:27 AM on 19 April 2011
       Christy Crock #4: Do the observations match the models?
       Gilles: As shown in the graph, the Arctic ice remains within the bounds of aggregate model run hindcasts/forecasts for Arctic sea ice extent until dropping below the average bounds in the first decade of the 21st century (although I can see it remains within the bounds of some of the model runs even then). As such, your claim to the contrary in #1 appears to be plainly false. What is your point? ===== Incidentally, the Arctic sea ice extent graph (Figure 2) would be a good addition to the Climate Graphics resource; assuming RealClimate allows it.
87960. muoncounter at 03:19 AM on 19 April 2011
       Christy Crock #3: Internal Variability
       GIlles#111: "It "just" changes the influence of forcings" Explain please. In specific terms, with specific forcings, in the context of this thread: over periods of a few decades, modeled internal variability does not cause surface temperatures to change by more than 0.3°C, and over longer periods, such as the entire 20th Century, its transient warming and cooling influences tend to average out "I already answered that precisely ... models converge towards an absence of drift " This should go to the 'models are unreliable' thread, where you will find your 'answer' makes little sense. But your position has descended into the circular: If models didn't converge, you'd be screaming they are unreliable; if they do converge, you claim that's what they are designed to do. Life must be good when you get to argue both sides.
87961. Albatross at 03:14 AM on 19 April 2011
       Christy Crock #4: Do the observations match the models?
       Dikran @5, Could you please specify which papers are you referring to?
       Moderator Response: [Dikran Marsupial] I have updated my post, it now includes links to the publishers website and to .pdf files (no paywall)
87962. Dikran Marsupial at 03:12 AM on 19 April 2011
       Christy Crock #4: Do the observations match the models?
       Christy is still citing a paper he co-authored with Douglass (www, pdf) as proof that the models don't match the observations of tropical trophopshperic temperatures, but doesn't mention that that paper was comprehensively refuted by a paper By Ben Santer and 16 other authors (www, pdf). The statistcal test used in the Douglass paper was obviously incorrect, and showed a complete lack of understanding of climate modelling. That the test was inappropriate is clearly demonstrated by the fact that a model with perfect physics, infinite temporal and spatial resolution and an infinite number of model runs (to perfectly capture the statistical properties of internal climate variability) is guaranteed to fail the test, even thought it is perfect. The test used in Santer et al. is rather better (if still too conservative).
87963. Albatross at 03:08 AM on 19 April 2011
       Christy Crock #4: Do the observations match the models?
       Dikran @3, "Can I suggest we ignore Gilles until he comes up with something a bit more substantive?" Agreed and seconded. To stay on topic. I find it intriguing how the "skeptics" are unsketpical of model findings should they happen to support their position (e.g., spencer's model), but otherwise they are deemed to be useless. As you may know, Lindzen is also guilty of Christy's mistake and deception on this file.
87964. Dikran Marsupial at 02:56 AM on 19 April 2011
       Christy Crock #4: Do the observations match the models?
       Gilles@1 GEP Box said "all models are wrong; but some models are useful". We all know the models are not going to get every prediction exactly right, it is unreasonable to expect them to do so. Nothing you have written suggests they are not usefull; if anything it suggests they under-estimate the possible threat. Can I suggest we ignore Gilles until he comes up with something a bit more substantive?
87965. Albatross at 02:54 AM on 19 April 2011
       Christy Crock #4: Do the observations match the models?
       James, Nice post. So yes, Christy deceived, again. And Christy also ignored the fact that the models are being too conservative on some important fronts. Just a couple of notes on that RC figure. The grey zone is the 95% confidence interval so +/- 2 standard deviations which is a very wide margin, the observed temperatures would probably almost exclusively fall within a +/- one std deviation envelope. Also the observed rate of warming compares very well with the projections, from RC, my notes in square brackets: For the GISTEMP and HadCRUT3, the trends are 0.19+/-0.05 [0.14-0.24] and 0.18+/-0.04ºC/dec[ade], [for the 1984-2010 period]. For reference, the trends in the AR4 models for the same period have a range 0.21+/-0.16 ºC/dec (95%).
87966. Gilles at 02:36 AM on 19 April 2011
       Christy Crock #4: Do the observations match the models?
       so to summarize * temperatures are "well within a range" .. so large that there would be very difficult to imagine how they couldn't (0.8 °C width with an average of 0.15°C/decade ! ) * sea level rise is just at the border * arctic ice is out of range of simulations .. that were already out since 1960 (obviously the trend didn't match the simulations even at the time when they were done ! ) * stratosphere has cooled... but not quite exactly as you should expect is the cooling was due to the blocking of LWR from below - which is supposed to increase regularly with time. Instead you seem to have abrupt changes after major volcanic eruptions (El Chichon and Pinatubo). Any idea why ?
87967. Albatross at 02:35 AM on 19 April 2011
       More Carbon Dioxide is not necessarily good for plants.
       Well, according to the 'skeptics', because we have increased CO2 by 40% above pre-industrial levels drought should no longer be much of an issue at all. But this is what is really happening on the ground during extreme drought: [Source] "Analyses of rainfall across 5.3 million square kilometres of Amazonia during the 2010 dry season, published tomorrow in Science, shows that the drought was more widespread and severe than in 2005. The UK-Brazilian team also calculate that the carbon impact of the 2010 drought may eventually exceed the 5 billion tonnes of CO2 released following the 2005 event, as severe droughts kill rainforest trees. For context, the United States emitted 5.4 billion tonnes of CO2 from fossil fuel use in 2009." Talk about a positive feedback! And more "cheering" news: "The authors suggest that if extreme droughts like these become more frequent, the days of the Amazon rainforest acting as a natural buffer to man-made carbon emissions may be numbered." A PDF of Xu et al. (2011) can be found here.
87968. Albatross at 02:17 AM on 19 April 2011
       More Carbon Dioxide is not necessarily good for plants.
       BP @103, "Let's see some real science." What a truly bizarre statement to make, especially after what you have done earlier on this thread. And since when is "your" science "real" science? I'll give the paper a read......good gracious I did not even have to get past the abstract. BP, please tell us why you chose to leave out this lesson from your list (which was so important that they included it in the abstract)? "Finally, the stimulation of yield by elevated CO2 in crop species is much smaller than expected." Oh and this, from the same paper: "Most important though will be understanding why our major food crops fail to achieve the improved production under elevated [CO2] that can be achieved in protected environments and by some non-crop species." There is some hope though: "Overcoming this could deliver a 10–15% increase in crop yields by 2050, an increase that could be critical with an anticipated 3 billion increase in global population coupled with climatic change adverse to crop production. " Yet from their final paragraph: "Overwhelmingly, this has shown that data from laboratory and chamber experiments systematically overestimate the yields of the major food crops, yet may underestimate the biomass production of trees." The authors clearly fail to see the hearty optimism of the 'skeptics'.
87969. villabolo at 02:13 AM on 19 April 2011
       More Carbon Dioxide is not necessarily good for plants.
       @111 CBDunkerson: David Horton wrote: "Anyone else get the feeling we are just wasting our time answering this kind of stuff?" I try to keep mental note of the people who have proven themselves completely beyond reason and ignore them. Granted, that leaves whatever nonsense they post 'un-rebutted', but any such can always be addressed later should anyone suggest that it could have validity. In echoing that sentiment let me emphasize that we have to address ourselves to the general public with the idea in mind that a "Skeptic' will be looking over their shoulders and spouting off his nonsense. That means that we don't really need to emphasize technical arguments/rebuttals but instead simplify the issues in order to "innoculate" the public.
87970. villabolo at 02:04 AM on 19 April 2011
       More Carbon Dioxide is not necessarily good for plants.
       @107 David Horton: "I am tired of that game." We need to play another game.
87971. Rob Honeycutt at 02:02 AM on 19 April 2011
       More Carbon Dioxide is not necessarily good for plants.
       DM @ 119... Totally agreed. You might say that BP "Moncked it up."
87972. Albatross at 01:58 AM on 19 April 2011
       More Carbon Dioxide is not necessarily good for plants.
       I would like to highlight a couple of things for readers, Arkadiusz made a post @83, trying to convince us that higher temperature will not be bad for the tropical forests. Two readers who took the trouble to dig a little deeper into the paper find that the results are not relevant to the current and future situation-- 200 years versus 10 000-20 000 time span. Now what does the skeptic do? Does he acknowledge this and cede the point? No, he ignores the critique and simply posts another paper @92. And nice try BP @97, but please do not insult our intelligence. You have been told repeatedly that this is not so much about where we have been or are but where we are headed if we continue under BAU. Your fraudulent graph was misleading and ignored the fact that its assessment agrees with the topic of the post-- moderate CO2 increases (and warming) favour an increase in biomass, but if CO2 goes way up, then vegetation does not fare well. Too much of a a good thing may very well be a bad thing. Try consuming a cup or two of salt to find out. Luke @100, Yes, you were speculating, thanks for confirming. I do not need links on how ENSO and IPO affect rainfall thanks, that is not what is at issue here so much as you claiming that we are headed for a period of more frequent La Ninas. That may or may not be true, but unless backed up by some science, it remans simple speculation. With that said, you seem to be basing your projection on the work of Verdon and Franks (2006). At least one of the papers that you cited has not helped you case: "Although there appears to be no overall trend toward wetter or drier conditions [over Queensland], the reconstructions suggest that the variability of rainfall and river flow has increased during the twentieth century with more very wet and very dry extremes than in earlier centuries, as projected for the region as a consequence of global warming." An increase of rainfall variability is not conducive for better crop growing conditions. And their work validates the IPCC projections. And I should have not have to point this out, but flooding (as was associated with this past La Nina) is clearly not conducive for agriculture either. Too much water is also a bad thing for crops and and other vegetation.
87973. Dikran Marsupial at 01:53 AM on 19 April 2011
       More Carbon Dioxide is not necessarily good for plants.
       Rob Honeycutt@116 For me the issue is that BP was using a graphic from a source that contradicts his position without mentioning that fact. It is a bit like taking a quote from a paper out of context to support an argument, where the paper as a whole supported an opposing position. Using a graphic or a quote from a report implicitly suggests that the report provides some support for your position. Somehow I don't think it would have passed without comment if say James Hansen had used a cropped picture from a climate skeptic report that was cropped in such a way as to ignore the central message of the report.
87974. Gilles at 01:46 AM on 19 April 2011
       Christy Crock #3: Internal Variability
       and an example of publication (but I'm sure there are others and you know it very well) http://www.esrl.noaa.gov/psd/people/gilbert.p.compo/CompoSardeshmukh2007a.pdf " Several recent studies suggest that the observed SST variability may be misrepresented in the coupled models used in preparing the IPCC's Fourth Assessment Report, with substantial errors on interannual and decadal scales (e.g., Shukla et al. 2006, DelSole, 2006; Newman 2007; Newman et al. 2008). There is a hint of an underestimation of simulated decadal SST variability even in the published IPCC Report (Hegerl et al. 2007, FAQ9.2 Figure 1). Given these and other misrepresentations of natural oceanic variability on decadal scales (e.g., Zhang and McPhaden 2006), a role for natural causes of at least some of the recent oceanic warming should not be ruled out. Regardless of whether or not the rapid recent oceanic warming has occurred largely from anthropogenic or natural influences, our study highlights its importance in accounting for the recent observed continental warming. Perhaps the most important conclusion to be drawn from our analysis is that the recent acceleration of global warming may not be occurring in quite the manner one might have imagined. The indirect and substantial role of the oceans in causing the recent continental warming emphasizes the need to generate reliable projections of ocean temperature changes over the next century, in order to generate more reliable projections of not just the global mean temperature and precipitation changes (Barsugli et al. 2006), but also regional climate changes." No need to say that if even the decadal variability may be "misrepresented", this can only be worse at the century timescale.
87975. Rob Honeycutt at 01:42 AM on 19 April 2011
       More Carbon Dioxide is not necessarily good for plants.
       David Horton @ 107... Yes, it's worth going through this over and over and over (IMHO). I always say this: It's not about changing anyone's mind who is posting here. We will never change Gilles, BP, or any other of the minds that are already made up. But in responding to their claims and debating their positions we have the opportunity to change the minds of others who come to SkS to read about this issue. Think of it as a public debate with a large audience. When you post here you are up on the stage making a point. You don't need to convince the person at the other podium whom you're responding to. You need to convince the audience. I would contend that the audience is always changing too. Even though we might have the same discussions here repeatedly with the cast of characters, there are more and more people reading SkS all the time. New minds ready to learn more about climate science. One of the great things about this site is the heavy moderation. When I go read WUWT it's more like you walked into a clubhouse where everyone thinks alike and is slapping each other on the back, and attacking anyone who doesn't think like they do. Here at SkS there is a more hearty, genuine debate.
87976. villabolo at 01:39 AM on 19 April 2011
       More Carbon Dioxide is not necessarily good for plants.
       @104 CBDunkerson: "As to the impact on plants specifically... it is well known (unless one is an evolution denialist also) that all lifeforms evolve to best survive within the environment around them. The longer a particular element of that environment is relatively stable the more time lifeforms will have to evolve to adapt to it. Atmospheric CO2 levels had been constrained to a range between about 180 and 280 ppm for millions of years. Every plant on the planet has therefor been evolving towards the ability to best survive within that CO2 range for millions of years. There is no way that they will all now be able to adapt to radically different CO2 levels within a matter of decades. Some will retain characteristics from higher CO2 periods in the past which will allow them to cope, but others will not." Excellent point. I was worried that a quick and easy "Skeptic" response would be to say something like; "In the good old Dinosaur days, plants did just fine with elevated CO2". The quick and easy rebuttal would be to say that plants had tens of thousands of years with which to evolve adaptations. Then one could bring up the Paleocene-Eocene Thermal maximum took 20,000 years to develop and yet major catastrophes ensued. As for the oxygen analogy, it would be better to revise it for basic level readers. Something like; "If the percentage of oxygen were to double, it would allow for massive fires. Even wet forests would burn."
87977. Rob Honeycutt at 01:23 AM on 19 April 2011
       More Carbon Dioxide is not necessarily good for plants.
       BP said..."It means the curve up to the point where I've clipped it can be checked using actual data, beyond that it is pure fantasy." You can claim that if you like but you need justification for making such a claim. By any standard you very definitely don't clip the way you did without noting that you've done so and explaining why you did it. I'm surprised that you're defending what you did instead of apologizing. Quite honestly, I'm going to have a very hard time taking anything you say seriously from here out.
87978. villabolo at 01:04 AM on 19 April 2011
       More Carbon Dioxide is not necessarily good for plants.
       @100 LukeW: ""And you want those La Ninas to get stronger?" YES PLEASE !! Would make us billions ! (with some collateral damage too but life wasn't meant to be easy) You would like another 20 year drought cycle instead ...?" I can see you're not Australian (Please tell me that your not). "Collateral damage"? Is this the military? Do you seriously think what they went through is worth a bumper crop of wheat; assuming it doesn't get ruined? Perhaps a cold blooded cost analysis is in order? How much lost in damage to homes and infrastructure versus how much gained by, what, a 10 or 20% increase in yield? Having mentioned billions of dollars to be made, please tell me how many billions will be lost? I believe I said it before; any hypothetical benefits to agricultural growth will be more than diminished by property and infrastructure damage; not to mention lives lost. Who gets to be the "winners and losers" in this scenario? Those who eat versus those who drown? If one were to play God then the wish would be for moderate La Ninas. But that's not what's going to happen. As for contrasting that with 20 year drought cycles, I really see that as a difference without a distinction. It's like having this choice:
87979. Gilles at 01:02 AM on 19 April 2011
       Christy Crock #3: Internal Variability
       "One could ask what relevance 'long timescale variability' has to the current forced climate change?" It "just" changes the influence of forcings accordingly . "The obvious answer to this point, is that as the references you yourself provided clealy state, modern GCMs don't exhibit these drifts and no longer need flux adjustments to correct them." I already answered that precisely here . No need to say it again - you just prove with your models what you have carefully worked out to get.
87980. Dikran Marsupial at 00:44 AM on 19 April 2011
       Christy Crock #3: Internal Variability
       Gilles@108 "If this were a generic feature of GCM models, then there wouldn't be any drift : everything should be "burnt-in" in a few weeks." The obvious answer to this point, is that as the references you yourself provided clealy state, modern GCMs don't exhibit these drifts and no longer need flux adjustments to correct them*. *_{Although the drifts are not solely due to initialisation anyway, so the argument was invalid to beign with} Sorry Gilles, I am bored with your trolling, it is obvious you have no substantive point to make, are not even reading your own sources, just quote mining, and are merley trying to disrupt sensible discussion. Sadly you have achieved your goal.
87981. Tom Curtis at 00:38 AM on 19 April 2011
       A Flanner in the Works for Snow and Ice
       Ken Lambert @83, if you multiply the TSI measured in Watts/meter squared by a number of factors representing atmospheric absorption, cloud and surface albedo, atmospheric absorption, and the extended surface covered by the incoming light due to the low angle of incidence; then further multiply by time factors of 60 and 60 and 24 and 90, it is not mathematically possible that what you have calculated is the cumulative energy flux over thirty years. And lest there be any doubt over what time period the incoming energy has been calculated, here is the relevant formula from my spread sheet, which calculates the energy input per meter squared from effective change in radiance absorbed by the surface as a result of sea ice melt: =I105*60*60*24*90 Put in the simplest terms, 60*60*24*90 =/= 60*60*24*365.25*32; 11688 does not equal 90. Nor is it a possible mathematical confusion that they are the same. I perfectly understand that you are getting desperate, defending as you are, the in defensible. But resorting to such ridiculous tactics as pretending to the confusion you apparently espouse only succeeds in making you look the complete fool. At this stage I cannot be any clearer about my method. As this is already a repeat of this information, there can be no basis for your confusion other than a pointless rhetorical strategy. Should you persist in this ( -snip- ) strategy, I will request that the moderators take notice of your obvious trolling.
       Moderator Response:

       [Dikran Marsupial] Bold tags (hopefully) fixed.

       [DB] Inflammatory term snipped.

87982. muoncounter at 00:30 AM on 19 April 2011
       Christy Crock #3: Internal Variability
       Gilles #106: "I don't have to "provide" evidence of long timescale variability " Of course not. You can just throw out the teaser of 'long timescale variability could be ... ' and not bother with evidence, proof or theory. That's the advantage of saying 'no' to everything you don't like. One could ask what relevance 'long timescale variability' has to the current forced climate change?
87983. bushybest at 00:30 AM on 19 April 2011
       More Carbon Dioxide is not necessarily good for plants.
       I give up on this post. There is so much non-science splattered around the comments and that includes the original posting.The whole thing is a scattergun target. How about a reality based and referenced article/post on actual science for a change? [personal attack snipped]
       Moderator Response: [Dikran Marsupial] Please read the comments policy and keep constructive criticism impersonal.
87984. Gilles at 00:29 AM on 19 April 2011
       Christy Crock #3: Internal Variability
       "This is of the order of a few weeks." If this were a generic feature of GCM models, then there wouldn't be any drift : everything should be "burnt-in" in a few weeks. What you don't understand is that when running a numerical model, you can only measure the characteristic variability timescales of the model itself, not of the reality it is supposed to describe. The limit cycle that can arise in a non linear ,chaotic model are generically *not* well predicted, again- and this is extremely difficult, and so to say impossible, to make a reliable diagnosis from this kind of computation. You're using an argument for "evidence" with a tool that is simply not appropriate for this use. Of course, there are plenty of signs of variabilities at hundreds or thousand years levels -and this is totally compatible with the order of magnitude of thermohaline circulation and heat transport timescales by the oceans.
87985. Alexandre at 00:22 AM on 19 April 2011
       More Carbon Dioxide is not necessarily good for plants.
       les at 22:58 PM on 18 April, 2011 That's a great system :-) Specially in these days of Science As A Contact Sport.
87986. Dikran Marsupial at 00:17 AM on 19 April 2011
       Christy Crock #3: Internal Variability
       Gilles@106 I explained earlier that the initial conditions don't affect the model ensembles provided you let them "burn-in". This "burn in" phase is presumably what you mean by "relaxation time scale". This is of the order of a few weeks. That is why numerical weather prediction is only accurate to a prediction horizon of a few days; that the models rapidly forget their initial conditions. Now if you have evidence that is not the case, lets hear it. The initialisation prescription given is basically just saying the models need to be properly burned in, while considering the need for the comparison. Nothing more. I am not cliaming there is no long timescale unforced variability, just that there is little evidence to suggest that such a thing exists and therefore it is not rational grounds for significant doubt on the model projections. If you want to assert that long timescale unforced variability is a reason to doubt the model projections then the burden is on you to give credible evidence that it even exists.
87987. Ken Lambert at 00:03 AM on 19 April 2011
       A Flanner in the Works for Snow and Ice
       Nice try Tom, You are forgetting that if we look at Dr Trenberth's 0.9E20 Joules/year (rounded up to 1E20 Joules in his Table) based on the 2004-08 period, and assume the same rate of heat energy accumulation for 31 years (1979 - 2010) then you will get 28E20 Joules as the total energy absorbed. And that is for sea ice melt alone. In the same 31 year period you are calculating 15.1E20 Joules - roughly half the Trenberth cumulative figure. In that period (31 years) assuming that Trenberth's global imbalance was something between 0.5 and 0.9W/sq.m (say 0.7W/sq.m average) or 112E20 Joules/year for 31 years, then the Earth would have accumulated 31 x 112 = 3472E20 Joules of extra heat energy. Your number of 15.1/3472 = 0.004 which is 0.4% of the Earth's uptake, and Trenberth's number 28/3472 = 0.008 or 0.8% of the total Earth's uptake in 31 years. This makes my original point quite well. The 4.4% of the globe surface above the Arctic circle actually accounts for 0.4% to 0.8% of the global heat energy imbalance absorbed based on your and Trenberth's figures.
87988. Arkadiusz Semczyszak at 23:57 PM on 18 April 2011
       More Carbon Dioxide is not necessarily good for plants.
       CBDunkerson Atmospheric CO2 levels had been constrained to a range between about 180 and 280 ppm for millions of years. Every plant on the planet has therefore been evolving towards the ability to best survive within that CO2 range for millions of years. < a href =http://meetingorganizer.copernicus.org/EGU2011/EGU2011-10649.pdf>Long-term effect of elevated CO2 concentration on temperature optimum of photosynthetic CO2 assimilation in two tree species, Holisova et al., 2011.: “The eight-year-old trees were grown in glass domes at the experimental research site Bílý Kˇríž in the Beskydy Mts. and they were exposed for three growing season to ambient (AC; 380 _mol(CO2) mol-1) and elevated CO2 concentrations (EC; 700 _mol(CO2) mol-1).” “Our data thus support the initial hypothesis that long-term growth of plants under elevated CO2 concentration leads to the acclimation of photosynthesis and other related processes to higher temperature.” Cited above species of trees live unchanged for millions of years - probably the "something" they need „the acclimation of photosynthesis” do „700 _mol(CO2) mol-1” ... Optimum photosynthesis for most species of C3 plants is 400-600 ppmv CO2. It is higher at higher temperatures . C4 formed as a response to unusually low levels of CO2 (<350 ppmv CO2). At 180 ppmv CO2 - some C3 species stop growing - less than 150 ppmv CO2 - the most die back (knowledge of "textbook").
87989. Tom Curtis at 23:48 PM on 18 April 2011
       Muller Misinformation #2: 'leaked' tree-ring data
       climatewolf #10, I'm sorry to hear about your real life crisis, and hope it has been resolved in a satisfactory way. I'm sure I speak for DB and John Cook as well when I say that we'ld be be delighted for you to continue reading, and commenting. It is after all, what the site is for. Certainly John Cook has never objected to my putting my layman's oar in.
87990. Gilles at 23:47 PM on 18 April 2011
       Christy Crock #3: Internal Variability
       "I have already explained to you that initial conditions do not affect the conclusion of model ensembles and why." which is wrong, or rather, depend on the relaxation time scale of the model. "So what evidence do you have that model projections are sensitive to the initial conditions? Again, search for "initialize" in http://www-pcmdi.llnl.gov/ipcc/standard_output.html, and you will find plenty of occurences such as : "should initialize from a point early enough in the pre-industrial control run to ensure that the end of all the perturbed runs branching from the end of this 20C3M run end before the end of the control. This will enable us to subtract any residual drift in the control from all runs that will be compared to it." if initialization is immaterial, why give a prescription ? "What evidence do you have that long timescale unforced variability is a significant part of the climate system?" I don't have to "provide" evidence of long timescale variability - the burden of the proof is for the one who claims there isn't. Do you claim that, or not ? you can provide either strong theoretical , or strong observational evidence. I would accept both. I just don't see where they are.
87991. Ken Lambert at 23:38 PM on 18 April 2011
       The e-mail 'scandal' travesty in misquoting Trenberth on
       Alec Cowan #135 Calm down Alec, the spray is amusing but fools no-one with the hyperbole and 'For God's sake don't you know that??' crude attempts at argument by intimidation. Just point out exactly the errors made in the K&D paper and where the numbers are wrong.
87992. climatewolf at 23:32 PM on 18 April 2011
       Muller Misinformation #2: 'leaked' tree-ring data
       Hi Tom Curtis, Apologies I was offline with a real life crisis the last few days. Thank you for your response, I see clearly the points you are making and thank you and DB for alieviating my concerns and explaining you POV. I hope you (all) and Mr Cook will not object to my continuing to read this site and dropping my very layman oar into the water on occasion to share my POV. I may not always agree with you on all points, but I will try to be as open minded as I can be and ask questions/challenge assumptions where I can in a positive manner. Regards Wolf
       Moderator Response: [DB] Best wishes for your situation and what the future holds for you. Your participation is welcome and valued in this forum.
87993. CBDunkerson at 23:32 PM on 18 April 2011
       More Carbon Dioxide is not necessarily good for plants.
       David Horton wrote: "Anyone else get the feeling we are just wasting our time answering this kind of stuff?" I try to keep mental note of the people who have proven themselves completely beyond reason and ignore them. Granted, that leaves whatever nonsense they post 'un-rebutted', but any such can always be addressed later should anyone suggest that it could have validity. Besides, if the thread remains short then the moderators usually have sufficient time to put in links to existing posts which give reality based evidence.
87994. Dikran Marsupial at 23:30 PM on 18 April 2011
       Christy Crock #3: Internal Variability
       Gilles@103 I don't recall anyone saying that computer models were the only line of evidence suggesting that long term unforced variations are unlikely. So the comment about changing stories is a strawman and you know it. This discussion stems from your question about initialisation of models on post 67. I have already explained to you that initial conditions do not affect the conclusion of model ensembles and why. If you want to show that they do, then you need to provide evidence. So far you have provided none whatsoever. You have not provided any evidence of long term unforced variability. Pointing out there is variability in the data does not mean that it is unforced. You can't have it both ways, if you dismiss the attribution of changes to forcings as being a "sociological feature of modern science", then it is equally a "sociological feature of modern science" for you to attribute it to unforced variability. So what evidence do you have that model projections are sensitive to the initial conditions? What evidence do you have that long timescale unforced variability is a significant part of the climate system? No word games, just give straight answers to those three questions.
87995. les at 22:58 PM on 18 April 2011
       More Carbon Dioxide is not necessarily good for plants.
       107 David Horton "Time really is up for all this" Maybe we need a new form of refereeingmoderation?
87996. HumanityRules at 22:55 PM on 18 April 2011
       Solar Hockey Stick
       The issue, as I see it, isn't whether the solar activity variation is high or low over the MWP/LIA period but rather whether that observation fits well with how we understand the 'control knobs' of the climate. There's an interesting series of papers in PAGES Newsletter March 2011. I don't know what PAGES is, suspect this work isn't peer-reviewed but it does appear to be showing work from some important scientists who work on this problem. I was struck by the conclusions in the modelling paper (starting page 7). I'll just reproduce the conclusion in full and leave it to yourself to decide just how much confidence we should have in our present understanding of the science. I think it's worth reading the rest of these papers. "Conclusions The results presented here highlight major discrepancies between millennium simulations and reconstructions. If proxybased reconstructions were considered reliable and changes in radiative forcing factors were responsible for the MCA–LIA reconstructed temperature signal, these results would have implications on our understanding of the MCA–LIA transition. These discrepancies suggest that either the MCA–LIA changes arose from internal variability only, or transient simulations with state-of-the-art AOGCMs fail to correctly reproduce some mechanisms of response to external forcing: for instance, changes in the tropics like the enhancement of the zonal gradient in the tropical Pacific is not well simulated, with implications for related teleconnections elsewhere. Most models have used relatively high TSI variations from the MCA to the LIA and their pattern of response is typically a uniform warming in the earlier period. In spite of this, there are considerable differences among the simulations that highlight a feasible influence of initial conditions and internal variability. Furthermore, if reduced levels of past TSI are given more credit, as in the MPI-ESM-E1 ensemble, the temperature response for the MCA–LIA is less uniform in sign and visibly more influenced by internal variability. Therefore, under both high and low TSI change scenarios, it is possible that the MCA–LIA reconstructed anomalies would have been largely influenced by internal variability."
87997. Gilles at 22:52 PM on 18 April 2011
       Christy Crock #3: Internal Variability
       0.015°C/yr of course.
87998. Gilles at 22:51 PM on 18 April 2011
       Christy Crock #3: Internal Variability
       I make no supposition : I just say that the use of computer simulation is not a good criterion to exclude long term variations, since both computation methods *and* initial conditions have been carefully selected with this criterion. Now you use a totally different argument by saying :"The unforced stabilty of the climate seems well established by the paleoclimate record. " because this argument doesn't rely at all on computer simulations but on observations ! so you change the argument and say now " but paleoclimate observations exclude a natural 0.15°C/yr during 50 years". Which is again wrong : paleoclimate data don't exclude this kind of variations. " Can you give an example of a major shift in climate that cannot be attributed to a change in forcing?" "being attributed" being not an objective variable, but kind of a sociologic feature of current science, I can't answer this question. I stick on facts. But a 0.5 °C variation in 50 years wouldn't certainly be called a "major shift in climate" for paleoclimatic data (after all, who in the world is living in a different "climate" from his parents ?) - and yes of course there are plenty of such variations in the past - that cannot clearly be attributed to a change in forcing.
87999. les at 22:34 PM on 18 April 2011
       More Carbon Dioxide is not necessarily good for plants.
       Got to be said, that FACE stuff is interesting. The plots look log (asymptotic) or, at best, log-linear; not exponential (that's the 'up shot') and compatible with point 6. of the blog post. As has been mentioned, one can expect some improvement when one or another resource becomes more abundant, allowing other resources which are already abundant to be utilized and that will self-limit... in system like that, you'd expect an asymptotic improvement in the absence of any negative influences (increase in premeditation etc.) Good data.
88000. Alexandre at 22:29 PM on 18 April 2011
       More Carbon Dioxide is not necessarily good for plants.
       David Horton at 22:24 PM on 18 April, 2011 I'm with you.

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