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Comments 94851 to 94900:

94851. Marcus at 10:19 AM on 4 March 2011
       Putting a new finger on climate change
       Ah thanks for that Jeff T. Though I was of the understanding that radioactive decay is also the reason for the increasingly "light" CO2 in the atmosphere-& how we can tell CO2 produced from burning coal over that produced by burning wood. Perhaps I'm thinking of C14, which has a longer half-life than C13 IIRC. I'm pretty sure that atmospheric testing of nukes screwed up the 14C levels, not the 13C levels-again, could be wrong though.
94852. WheelsOC at 10:04 AM on 4 March 2011
       Roy Spencer’s Great Blunder, Part 3
       Read all three installments back at your blog. Thanks for this illuminating exercise. I wonder if we can convince Steve McIntyre to perform an "audit" of Dr. Spencer's model.
94853. e at 09:27 AM on 4 March 2011
       Hockey Stick Own Goal
       angusmac @132, To further Tom's point, consider also this statement from the Ljungqvist paper: The proxy reconstruction itself does not show such an unprecedented warming but we must consider that only a few records used in the reconstruction extend into the 1990s. (emphasis mine) Furthermore it is quite clear that no reconstructed data in this case was available for the 2000s. Given that it is now 2011, the assertion that "if you compare proxies with proxies ... the MWP was as hot as today" is not and more importantly cannot be supported by the proxy data alone.
94854. Rob Honeycutt at 09:05 AM on 4 March 2011
       Crux of a Core, Part 1b
       Yup. Here it is... Bond event 5:
       Moderator Response: [DB] Fixed image.
94855. Rob Honeycutt at 09:01 AM on 4 March 2011
       Crux of a Core, Part 1b
       Just to add a little perspective... here would be a more appropriate combining of the GSIP2 and Vostok data: You can see how there is a very broad correlation between the two but for the most part only in terms of timing for when we come out of the last glacial. The temperature swings in the GSIP2 record are extreme compared with the Vostok record. By stretching the Vostok record to fit the GISP2 scale Dr Hall is hiding a tremendous amount of information about how these two records relate to each other. If you look closely at the early holocene you can see that one huge jump in the GISP2 data is clearly antiphased with an equally profound response in the Vostok record. So, the one event in the GISP2 record that shows a greater temperature trend that the current warming has a counter response in Antarctica. I'm still looking into Bond events, but I believe that is specifically called Bond event 5 at 8200 years BP.
94856. Jeff T at 08:56 AM on 4 March 2011
       Putting a new finger on climate change
       @actually thoughtful and Marcus, DB explains the carbon isotope ratio in the post, but some further clarification might help. C12 and C13 are the stable isotopes of carbon. The ratio C13/C12 is about 1% on earth (C14 is much less abundant. It is radioactive and is used for dating biological materials, but it is not the subject of the post.) Since plants have a preference for C12, biological materials are enriched in C12. Consequently, the ratio C13/C12 is smaller in fossil fuels than it is in the atmosphere and burning of fossil fuels ought to dilute C13 in the atmosphere. The figure confirms that expectation. (The red scale in the figure is inverted. Although the red curve goes up to the right, the ratio C13/C12 is decreasing with time.)
94857. Tom Curtis at 08:36 AM on 4 March 2011
       Hockey Stick Own Goal
       angusmac @132, your contention that it is inappropriate to compare the recent instrumental record with past proxy records is incorrect. The simple fact is that we do not have a broad range of proxy records with global coverage extending to the very recent past, with most proxy records extending to the 1990's at best. Therefore, a comparison of proxy records alone must be restricted to a comparison of 1980's temperatures to past temperatures, which as you point out, show near equality. But, we know from the instrumental record that the 2000's are substantially warmer than the 1980's. To insist that we should then ignore that additional knowledge is specious, and if we do not the conclusion that current temperatures are probably warmer any in the MWP or Roman WP follows. Of course, ideally we would extend the proxy record to the most recent times with high quality proxies that continue to track local temperatures over the whole calibration period. Can I expect you to by lobbying your local politician's to pay for just such an effort? Having said that, I disagree with the moderator's (DB's) responce. Northern Iberian temperatures are regional temperatures, and by themselves cannot be used as a proxy for global temperatures - a point being well established in the "Core of the Ice" threads.
       Moderator Response: [DB] I'm sorry, Tom, if that is how that is being interpreted. My intent was to compare the Iberian data only to "the MWP is warmer" claim. Your entire statement here is 100% correct. I have added a clarification to my response to angusmac accordingly.
94858. Daniel Bailey at 08:30 AM on 4 March 2011
       Twice as much Canada, same warming climate
       Tamino has a new post up: Spring training's going to be rough on dos' playing da outdoor hockey up der, eh? The Yooper
94859. invicta at 08:22 AM on 4 March 2011
       No Illusions podcast interview (and elocution lessons from an 11 year old)
       invicta Maybe the question is what 'matters most, style or substance?' I have to agree with Johns daughter regarding his front of microphone technique but the replies he gave directly addressed the question and were scientifically defendable. If you compare this with for example the performance of Monckton (see Monckton Myths) whose utterances litter the web, he (Monckton) is able to answer any question with breathtaking disregard for the science and ,if this doesn't break the posting policy of sks, the universally accepted truth without so much as an er um or hint of a blush. 97% of climate scientist agree the basic argument of AGW is won but the struggle to convince the wider public and therefore electorate has a long way to go. Communication is a key part of this. BTW if you think things are bad with a eleven year old knowing everything just wait until she's sixteen.
94860. scaddenp at 08:03 AM on 4 March 2011
       Ice age predicted in the 70s
       thepoodlebites - I prefer my opinions to based on reliable data dont you?
94861. Daniel Bailey at 08:02 AM on 4 March 2011
       Prudent Path Week: Polar Regions
       Hey, I'm going back-to-back! Does that make me a double-threat? ;) Patrick Lockerby has just posted his first Arctic Ice update of 2011 in which he also suggests the melt has probably begun (see his post here). A teaser quote:

       "...why I expect the central Arctic to be essentially ice-free by the end of this Arctic summer 2011"

       I luv melt season! The Yooper
94862. actually thoughtful at 08:01 AM on 4 March 2011
       Putting a new finger on climate change
       Marcus - thank you that explains that very well. And then when we tested nukes on the surface we messed up C12/C13 ratios again?
94863. Peter Offenhartz at 07:58 AM on 4 March 2011
       Roy Spencer’s Great Blunder, Part 3
       What a brilliant, thorough and energetic analysis! A LOT of work went into your piece. Thank you!
94864. dhogaza at 07:55 AM on 4 March 2011
       Climate Sensitivity: The Skeptic Endgame
       "Oh really ? what is your guess of how many toe these sources will produce in, say, 20 years ? " Fracking of known natural gas reserves in the US would provide 100% of US consumption for roughly 100 years. This estimate comes from the oil companies who are making the hard-dollar investments in exploiting the resource. "Yes, peak oil says something : that the official estimates of resources are unreliable." True, unreliably *low* as a combination of 1) new extraction technology becoming available 2) exploration efforts uncovering new reserves 2) prices rising cause reserve estimates to rise.
94865. les at 07:53 AM on 4 March 2011
       Climate Sensitivity: The Skeptic Endgame
       79/89 Eric .... I dunno... a quick google turns up Representing uncertainty in climate change scenarios: a Monte-Carlo approach, Mark New and Mike Hulme which seems to take the approach along the lines I'd imagine.
94866. thepoodlebites at 07:40 AM on 4 March 2011
       It's Pacific Decadal Oscillation
       #73 Feb. 2011 UAH, -0.02, not as low as I thought. It will be interesting to see how 2011 pans out. The PDO is still negative and La Nina is hanging in there. I don't follow what you are predicting for this La Nina, Nino 3.4. Some La Nina cycles last longer than others but there is no clear trend that I can see. Before 1980, we had no El Nino's >+1.8 C between 1950 - 1971, note: during negative phase of the PDO, then 1972 (+2.1), 1983 (+2.3), 1998 (+2.5), 2009 (+1.8). And La Nina's, 1955 (-2.0), 1973 (-2.1), 1984 (-1.1), 1988 (-1.9), 1999 (-1.4), 2010 (-1.4).
       Moderator Response: [DB] Tamino has a post for those who see meaning in cycles where statistical significance tests show none here.
94867. Eric (skeptic) at 07:28 AM on 4 March 2011
       Climate Sensitivity: The Skeptic Endgame
       Parameter A should read Parameter P above.
94868. Eric (skeptic) at 07:27 AM on 4 March 2011
       Climate Sensitivity: The Skeptic Endgame
       les, let me try to simplify (and perhaps oversimplify). A model uses parameter P to determine (among others) measurement M. Measurement M can also be measured in reality for the current climate. Parameter A can be tuned so that the model matches reality in the sense that N runs of the model will produce the probability distribution matching reality. The problem is that works for the current climate and adding AGW to the climate may change parameter P. An example is weather-related parameters in GCMs because they don't have sufficient resolution to model it. For P there are merely various estimates each of which produces a different probability distribution for M. There is no simple way to combine estimates, even they had associated certainties, with model results to produce an aggregate distribution.
94869. angusmac at 07:21 AM on 4 March 2011
       Hockey Stick Own Goal
       Dana in your post, "Contrary to the Idsos' claims in the Prudent Path document, Ljungqvist says the following when combining his proxy reconstruction with recent instrumental temperature data: Since AD 1990, though, average temperatures in the extra-tropical Northern Hemisphere exceed those of any other warm decades the last two millennia, even the peak of the Medieval Warm Period." However, the actual statement by Ljungqvist (2010) (my emphasis added) appears to contradict your contention: "Substantial parts of the Roman Warm Period, from the first to the third centuries, and the Medieval Warm Period, from the ninth to the thirteenth centuries, seem to have equalled or exceeded the AD 1961-1990 mean temperature level in the extra-tropical Northern Hemisphere. Since AD 1990, though, average temperatures in the extra-tropical Northern Hemisphere exceed those of any other warm decades [of] the last two millennia, even the peak of the Medieval Warm Period, if we look at the instrumental temperature data spliced to the proxy reconstruction. However, this sharp rise in temperature compared to the magnitude of warmth in previous warm periods should be cautiously interpreted since it is not visible in the proxy reconstruction itself." The crux of Ljungqvist's statement which you have minimised, is that the, "instrumental data spliced to the proxy reconstruction" should be cautiously interpreted because the recent proxy data does not emulate the recent instrumental data. In a nutshell this is the "divergence problem." Re your comment that, "Indeed by plotting data along with Moberg et al. (2005), Mann et al. (2008), and the surface temperature record, we can confirm that the three reconstructions are very similar, and all show the peak of the MWP approximately 0.5°C cooler than today's temperatures (Figure 1)." Your statement that the MWP is 0.5 °C cooler than today is incorrect because you are comparing today's instrumental measurements with yesterday's proxies. To compare instrumental temperatures with proxy temperatures is physically and statistically wrong. The correct methodology is to compare today's proxies with previous proxies. I enclose Ljungqvist's original reconstruction in Figure A and I have removed the instrumental calibration data in Figure B for clarity. Figure A: Ljungqvist's Reconstruction with Instrumental Data that was used for Calibration Figure B: Ljungqvist's Reconstruction with Instrumental Data Deleted It is evident from Figures A and B that the MWP was at least as warm as the current warming period. Moberg (2005) and Mann (2008) show similar results when proxies are compared with proxies. Therefore, a correct interpretation is that all three reconstructions show that recent temperatures are similar to the MWP. From the foregoing, it would appear that the Prudent Path does support its claim that, if you compare proxies with proxies in your three reconstructions, the MWP was as hot as today.
       Moderator Response: [DB] Recent evidence shows that the current warmth experienced in Europe is unequaled in the last 4,000 years (another post on this topic is also imminent):
94870. e at 07:04 AM on 4 March 2011
       Climate Sensitivity: The Skeptic Endgame
       In fact Gilles the "long tail" probability distribution means our sensitivity estimates are more likely to be too low than too high, quite the opposite of what you are implying.
94871. Marcus at 07:01 AM on 4 March 2011
       Putting a new finger on climate change
       actually thoughtfull. I'm not 100% sure, but the reason I recall is that naturally occurring CO2 has roughly equal amounts of heavy & light CO2-which is then taken up by plants & trees. However, in the case where that CO2 was taken up *hundreds of millions of years ago*, all the heavy carbon will have decayed, leaving behind only the light CO2. So when you chop down & burn a tree which is only a few hundred years old, you'll get a relatively even mix of isotopes, but when you burn coal or oil, you'll get nothing but light CO2. Hope that explains things.
94872. bbickmore at 06:30 AM on 4 March 2011
       Roy Spencer’s Great Blunder, Part 3
       Actually Thoughtfull @4, I tried exceptionally hard this time not to be too hard on Spencer-the-person, and I did listen to the commenters on the last installments. It helped when I was able to figure out how he might have gotten his best-fit parameters by sheer luck (combined with a bad statistical technique). In any case, in Part 2 I think I was a little extra hard on him because it REALLY bothers me how he blatantly mischaracterizes his opponents' position. It's one thing to botch a curve-fitting job because you don't have much experience with it. It's quite another to knowingly tell whoppers about what the other scientists think. And he did know, as I demonstrated.
94873. les at 06:25 AM on 4 March 2011
       Climate Sensitivity: The Skeptic Endgame
       69 Giles I see what you're saying. I'm not at all sure that they are not doing just what I describe... it's a review paper, so a bit short of detail. In Knutti and Hegerl I can't for the life of me see any discussion of the probability of a model being right or wrong?!? But when someone says something like:

       running large ensembles with different parameter settings in simple or intermediate-complexity models, by using a statistical mode

       they are doing what I described. In which case the likelihood function is what I said. 70 EricI think I understand how models are parameterized - I was looking for a demonstration that "perturbing parameters is not probabilistic". The proof of a model (or models) is how they compare to reality. When their parameters aren't known precisely (irrespective of what the parameters are) runs of models can be used to give estimators of how well they compare to reality covering the parameter space.
       Moderator Response: [Dikran Marsupial] runaway blockquote fixed
94874. actually thoughtful at 06:23 AM on 4 March 2011
       Putting a new finger on climate change
       Meant carbon13 vs carbon 12 above.
94875. actually thoughtful at 06:20 AM on 4 March 2011
       Putting a new finger on climate change
       Daniel, Interesting, and a great study that seems approachable. I got lost though, in why there is more CO213 now than there was then? And what do the pink and blue lines in your top graph tell us? That we have less free O2 in the air because we are burning C and adding O to create C02?
       Moderator Response: [DB] The pink & blue are from different locations, showing the decline of global oxygen levels as more fossil fuel CO₂ is injected into the global carbon cycle, locking up oxygen atoms with the carbon atoms. A solid confirmation that "it is us". The study referenced above uses paper from dated issues to derive these ratios; see here for their results. Good questions. (Edit: Sorry for the screw-up; was bleary-eyed from 2 posts in 1 day; the portion of the graph in question concerned the O₂ levels, not the Carbon isotopes as I previously wrote)
94876. dana1981 at 06:12 AM on 4 March 2011
       CO2 limits will harm the economy
       BP #7 - as discussed in Monckton Myth #11, we have examined studies using discount rates ranging from 1.4% to 5%. In every case the benefits of carbon pricing exceed the costs several times over.
94877. e at 06:10 AM on 4 March 2011
       Climate Sensitivity: The Skeptic Endgame
       >And yes, there are good reasons for a high bias - starting with the skewness of the amplification retroaction function 1/(1-f) The "skewness" of this function simply means that we will always have more certainty about the lower bound than about the upper bound. It does not in any way imply that the bounds are less certain than calculated. It is ridiculous to refer to this as a "bias."
94878. NewYorkJ at 06:00 AM on 4 March 2011
       Crux of a Core, Part 1b
       Finishing my last paragraph... On a related note, there's an important distinction between "recent warming" and "recent warmth", which can be mistakingly used interchangeably. One refers to rate of change and the other to magnitude. It's easy to show "recent warmth" is not unprecedented. The Holocene peak was possibly a little warmer than recent temperatures, and of course millions of years ago when dinosaurs roamed the Earth it was considerably warmer. Hall uses the phrase "recent warming". Over the last 2000 years, there has not been a rapid rise in temperature over a century equivalent of the last century. There are rare events in geological time that I believe exceed the rate of recent change. Although a cooling event, and mainly localized, it seems Younger Dryas would be a candidate. Such natural events also would be very likely detectable today. There's no natural mechanism that explains recent warming.
94879. Daniel Bailey at 05:58 AM on 4 March 2011
       Prudent Path Week: Polar Regions
       Speaking of a warming Arctic and a decline in the sea ice there, it looks like the Great 2011 Arctic Melt Season may be underway: "Heigh-ho, heigh-ho, it's off to melt we go..." The Yooper
94880. NewYorkJ at 05:58 AM on 4 March 2011
       Crux of a Core, Part 1b
       Gilles (#17), The instrumental record appears to extend another decade. Note the recent decade is more than 0.5 C warmer in the Arctic regions than the previous one. 2000-2009 compared to 1990-1999 I often see contrarian types remove the instrumental record entirely, which often means cutting off 30-50 years of data, then claiming MWP was warmer than the "recent period". See also: Kaufman 2009 A few of the proxies appear to be high latitude tree rings, which might have the modern divergence problem Regarding scaling, if the purpose is to just show a correlation, there's no need to do the scaling, unless one is trying to greatly exaggerate very weak correlations. Scaling is appropriate if you have entirely different unrelated measurements, such as temperature vs TSI. Furthermore, Hall doesn't even accomplish showing a correlation in the context of his initial graph. Recall that his initial graph focused on the recent 10,000 year period. From his new "correlation" graph, which increases the time scale by an order of magnitude, the last 10,000 years are just a blur, and finding any correlation over that period is impossible. Also note that Hall is ultimately claiming recent global warming is not unprecedented, and using the scaled graph to support the idea that there were steep variation in other regions. To follow his lead, maybe we should scale recent global temperature changes 5x, which would show 4 C of warming over the last century. On a related note, there's an important distinction between "recent warming" and "recent warmth", which can be mistakingly used interchangeably. One refers to rate of change and the other to magnitude. It's easy to show "recent warmth" is not unprecedented. The Holocene peak was possibly a little warmer than recent temperatures, and of course millions of years ago when dinosaurs roamed the Earth it was considerably warmer. Hall uses the phrase "recent warming". Over the last 2000 years, there has not been a rapid rise in temperature
94881. Albatross at 05:56 AM on 4 March 2011
       Roy Spencer’s Great Blunder, Part 3
       Dr. Bickmore, Thanks, a fascinating read! I need to reflect on this. A significant part of my MSc involved conducting sensitivity tests for a relatively simple model used to simulate a particular microphysical process. We varied key parameters (some better constrained than others) over the ranges specified in the literature. That is, we made sure to vary the parameters within the appropriate and physically valid parameter space. It appears that Spencer failed to do this. Really, the appearance of the word "blunder" in the title of his book seems to speak to his blunders rathe than the alleged "blunders" committed by his colleagues. Sadly, I suspect that Spencer will try and wiggle his way out of this one too. As for " and the editor of Geophysical Research Letters was absolutely right to send him packing with his curve-fitting paper." Going by your independent analysis, the journal was indeed correct to reject his paper. Good job. This series does not exactly instil much faith in his published work-- perhaps an audit of his published works (similar to what has been done here) is in order. Sadly, though, Spencer's work is not critically viewed by so-called 'skeptics' and they love it-- talk about faux skepticism and confirmation bias.
94882. dana1981 at 05:47 AM on 4 March 2011
       Climate Sensitivity: The Skeptic Endgame
       Sorry Giles but you last comment didn't make any sense to me. If you want to claim that every single climate sensitivity estimate is biased high, please provide some supporting evidence.
94883. Gilles at 05:45 AM on 4 March 2011
       Climate Sensitivity: The Skeptic Endgame
       mucounter : Dana has given a good definition of accurate : "mean measurements with relatively high confidence and small error bars." I don't see how to qualify the error bars as small", in normal scientific standards.
94884. Gilles at 05:42 AM on 4 March 2011
       Climate Sensitivity: The Skeptic Endgame
       Dana, the issue is that the discussion is precisely on this point : are the estimates systematically biased towards high values, or not ?if skeptical people think they are, they perfectly know that most estimates are rather high - so saying again they're high doesn't bring much to the debate, in my opinion. And yes, there are good reasons for a high bias - starting with the skewness of the amplification retroaction function 1/(1-f)
94885. actually thoughtful at 05:34 AM on 4 March 2011
       Roy Spencer’s Great Blunder, Part 3
       Speaking as one who thought the last installment was a little hard on Spencer-the-person - this is a GREAT article! It walks us through the problems, very clearly and very convincingly. The tone is excellent, and science based. One thing it revealed for me is that Spencer, without the commentary, was reasonably persuasive. I though the mix layer WAS 700 meters. I don't have the frame of reference to even ask the right questions. So great, Professor Bickmore protects me from being taken in by Spencer. But I didn't see where Spencer was wrong, so perhaps I just can't see where Bickmore is wrong? I think I am smart enough (barely) to recognize better methodology and transparency by Bickmore - to recognize a better process. But how many people are going to be able to do that? (And yes, I am implicitly stating I am at least more stubborn, if not smarter, than your average bear (to get through the above post.)) As the skeptics get more sophisticated, the arguments require actual thought and effort to refute. And here the skeptics win. It is easier to say/understand "Climate has changed before" or more colorfully "It must have been the SUVs the dinosaurs were driving" than to say "Past climate changes are understood and explained by models that can only explain current warming if human activity is included." And then explain what THAT means. Yes we can wring our hands and hope that science and knowledge prevail, but look at the US House of Representatives now. They are voting to defund the EPA, they openly mock climate science. They attribute the scientists' results to greed (the truest case of DoubleSpeak I know of). These guys are the policy drivers for the largest economy and the nation on earth that pollutes the most. Regardless, I really appreciate the post.
94886. muoncounter at 05:31 AM on 4 March 2011
       Climate Sensitivity: The Skeptic Endgame
       Gilles: "my point is that if a theory is not accurate, a "likelihood" estimate based on the number of models giving such and such value has no real signification." You apparently have concluded that the theory is not accurate, so you feel justified in dismissing the model results. But you have yet to substantiate that the theory is not accurate. Absent that, the fact that multiple models overlap, as noted by dana, is evidence that we are converging on a perfectly reasonable sensitivity. So the question turns back to you: what part of the theory behind AGW or GHG-forced warming do you claim to be inaccurate? What justification do you offer for a different sensitivity, presumably based upon your new, improved theory?
94887. e at 05:06 AM on 4 March 2011
       Is the airborne fraction of anthropogenic CO2 emissions increasing?
       Tshane, Simple example: Let's say year one you add 2 tons of CO2 into the atmosphere. If the atmospheric fraction is 50%, then that means 1 ton stays in the air and 1 ton is absorbed by nature. The CO2 concentration has also increased because there is an additional ton of CO2 in the air. There is more CO2 in the air than before both in terms of total amount and as a fraction of atmospheric mass. Now let's say year 2 you again release 2 tons of CO2 and again 1 ton stays in the air and 1 ton is absorbed by nature. The atmospheric fraction is still 50% because half of the new CO2 emissions have been absorbed by nature. However, CO2 concentration has increased because now you have 2 extra tons of CO2 in the air instead of just one (1 ton from year 1 + 1 ton from year 2). Does that clear things up?
94888. Dikran Marsupial at 04:47 AM on 4 March 2011
       Is the airborne fraction of anthropogenic CO2 emissions increasing?
       Tshane3000 The airborne faction is not the fraction of the atmosphere that is due to anthropogenic emissions (as implies by your statement 2), it is the fraction of what we have emitted that is still in the atmosphere. If we have emitted 200 units of carbon dioxide since the start of the industrial revolution and atmospheric carbon dioxide has risen over that time by 100 units then the aurborne fraction would be 0.5 becuase only half of the carbon we have so far emitted is still in the atmosphere. If we had emitted 400 units and atmospheric levels had risen by only 50 units, then the airborne fraction would be 50/400 = 0.125 Carbon sinks are only taking up *some* of our emissions. The airborne fraction is currently about 0.45, which means that the environment is soaking up about 55% of what we are currently emitting. The remaining 45% though goes into the atmosphere, where it increases the greenhouse effect. It is probably best to get to the bottom of one issue before moving onto the next.
94889. CBDunkerson at 04:39 AM on 4 March 2011
       Putting a new finger on climate change
       At some point we'll probably want to differentiate between fingerprints like this one which indicate that humans are responsible for rising CO2 levels and fingerprints which indicate those rising CO2 levels are responsible for significant/observed global warming. At this point I think it is really only the completely clueless (though that is sadly not a small group) who question that humans are causing CO2 levels to rise. On the other hand, you still have people like Spencer denying that humans are responsible for much of the warming observed thus far... despite fingerprints (e.g. faster warming at night) directly contradicting his alternate explanations.
94890. dana1981 at 04:35 AM on 4 March 2011
       Roy Spencer’s Great Blunder, Part 3
       Great series and this was my favorite post. Very interesting to see Spencer's modeling step by step, and how unrealistic his parameters were.
94891. dana1981 at 04:33 AM on 4 March 2011
       Climate Sensitivity: The Skeptic Endgame
       Giles - of course it's possible that every study is biased, but it's a very remote probability. That's why the IPCC states that it's very likely, not certain, that climate sensitivity is above 1.5°C. You haven't given any reason to believe the IPCC is incorrect on this issue.
94892. Eric (skeptic) at 04:23 AM on 4 March 2011
       Climate Sensitivity: The Skeptic Endgame
       les, the model parameters are mostly used in place of higher granularity simulation. A mesoscale model with a 1km grid can do a reasonable job simulating precipitation patterns and the weather consequences: temperature, soil moisture, etc. The consequences follow a probability distribution and can also be measured to derive a distribution for a given weather pattern. But that same approach won't work with coarser GCMs. The problem is that the causal parameters like convection cannot be described in a probability distribution because they depend on the rest of the model. For example I can't posit a probability distribution for cumulous formation in my location under any particular conditions. I can measure the clouds over a length of time with varying conditions (broader weather patterns) and get a probability distribution. But I can't translate a particular condition (e.g. today's) into a probability distribution. Well, actually I could, but it's a very hard problem. I need to capture about 30 days "like today" which means looking at a lot of parameters that are difficult to model or even measure like soil moisture. So a model would have to store probability distributions for every parameter in every grid under every condition in order to derive a realistic probability distribution for any model result. Otherwise the resultant distribution simply depends on choices for parameters that are not modeled (too coarse of a model) and aren't measured. As the paper implies, the shape of the "sensitivity" distribution is controlled by parameter choices, not model runs or measurements.
94893. Gilles at 04:19 AM on 4 March 2011
       Climate Sensitivity: The Skeptic Endgame
       KR : I didn't claim that Hansen paper was about annual variations. BTW, do you know the answer to my question, and the explanation ? les : the point is : it is justified to estimate the likelihood of parameters WHEN the theory is well known and validated. It is not justified to estimate the likelihood of a theory itself. Can you estimate the likelihood that the string theory is correct or that dark matter really exists? no. It's just open questions. Dana : you stated precisely that the climate sensitivity was accurately determined by volcanic eruption, which, I think, would require * an accurate estimate of the negative forcing volcanic aerosols *an accurate estimate of the variation of temperature due to these aerosols alone, once the natural variations properly subtracted. I don't think either of these two quantities is easy to quantify, but may be you know a reference? now for you point that it would require that all study should be biased systematically towards the same direction - yes of course, it's possible, definitely.
94894. Tshane3000 at 04:04 AM on 4 March 2011
       Is the airborne fraction of anthropogenic CO2 emissions increasing?
       Thanks for the replies, Bibliovermis and Dikran. But it is *still* confusing. Dikran Marsupial: "There is no contradiction in the two statements from the IPCC. The airborne fraction is the proportion of anthropogenic emissions that remain in the atmosphere [caveat: simplified definition]. If the airborne fraction remains constant, the amount of additional carbon dioxide in the atmosphere will still increase as our cumulative emissions are also increasing." So why does the concentration increase, but the fraction shows constant? Does this mean the volume of total air is increasing along with the volume of CO2 emitted by humans (and volcanoes, natural emitters, etc.), so the percentage of CO2 (airborne fraction) is constant? (Air increases, CO2 increases in air, so percentage or fraction of CO2 is constant?) If this is correct, a way to communicate that should be clear: 1) CO2 is increasing in the atmosphere. This is bad. (State the reason and the effects--simply.) 2) CO2 as a percentage of the atmosphere is the same. THis is good. (State the reason and the effects--simply.) And doesn't this simply (and only) mean that carbon sinks (oceans, trees, vegetation, etc.) are taking up the CO2 we put out? It does *ot* imply other things--for one, that carbon sinks are healthy for taking in the carbon! It's just a dry, factual statement with numbers and percentages. For example, World Climate Report blog claims "Coral Reefs Expand As the Oceans Warm"--reefs are expanding as a result of ocean warming near Japan. Other places are not mentioned. (http://www.worldclimatereport.com/index.php/2011/02/18/coral-reefs-expand-as-the-oceans-warm/#more-475) This would contradict (or better, ignore) overwhelming evidence that, partly because of CO2 turning oceans more acidic, coral reefs are shrinking and dying overall. So the overall significance is *not* just that the ocean is warming, but that the warming is only one effect of climate change--with some positive but mostly negative consequences. They are ignoring the effects of acidification. World Climate Report: "And it is this opposite effect—a positive impact of [sic? do they mean "on"? --Tshane] coral reef communities and their dependents—that is routinely left out of climate change impact assessments." Isn't that just cherry-picking the science for "good news" in a sea (literally) of bad news caused by CO2 emissions? Also leaving out the overall effect of warming oceans by focusing only on the Japan research? Do climate change assessments "routinely" leave out positive impacts? To be true, this blanket statement would have to evaluate every climate change assessment referenced for what's left out, what was considered, and what was not. But...I don't see that kind of detail and broad scientific, methodical focus in their report.
       Moderator Response: Your point regarding cherry picking positive effects is similar to the Positives and negatives of global warming post. FYI this site's List of Skeptic Arguments is great way to find rebuttals to common skeptic arguments. Keep it in mind and resist the urge to stray off-topic, it really does help keep this site readable and organized, which ties into your argument about clear communication of the science.
94895. Alexandre at 03:58 AM on 4 March 2011
       Roy Spencer’s Great Blunder, Part 3
       "Skeptics" often dismiss climate models as some piece of fiction that gives the biased result the scientist desired. Well, they can, if you don´t test them enough against reality, and that´s one of Spencer's big flaws here. OTOH, the models that receive the bulk of "skeptic" criticism make accurate predictions. Very interesting analysis. Thanks Barry.
94896. Tom Curtis at 03:53 AM on 4 March 2011
       Crux of a Core, Part 1b
       garythompson @11, you asked if any other proxy's date back as far as the ice cores. The following proxy is from 40 deep sea drilling projects, so it has a fair claim to in fact representing global temperature changes: This focuses on the last 400 thousand years. The top image is from Antarctica (Dome C), while the bottom is a detail of the above drill data. The blue line is the calculated temperature based on known forcings with a climate sensitivity of 3. Focusing still closer, we have the and of the last Glacial, and the Holocene. On the left had side, blue is Vostok, Green is Dome C, and red a closer detail of the deep sea data. On the right, the three lines represent three different ocean basins. In the second two graphs, ice core data is scaled by multiplying by 0.5, and deep sea cores by multiplying by 1.5. This is justified, in part in that the ocean depths do not exhibit as much temperature variation as the surface, and the poles exhibit more than the tropics, and hence the global average. Of course, you may wish to argue that the antarctic data should not be scaled so drastically. Just remember that you will need to scale the climate sensitivity with the antarctic data. Thus if you insist the Antarctic data is representative of global temperatures without need to scale, then you are committing yourself to a climate sensitivity of 6. All graphs come originally from Hansen and Sato 2011.
94897. michael sweet at 03:49 AM on 4 March 2011
       Is the airborne fraction of anthropogenic CO2 emissions increasing?
       Tshane, Here at skeptical science we are about the airborne fraction. That is why this thread exists. It is discussed as a side item in other threads. You probably have not noticed it being discussed. The airborne fraction is not the same as concentration. Many people are confused by that. CO2 concentrations are increasing in the atmosphere as measured at Mauna Loa (and other stations). The volcanic gases do not interfere with the measurement. Your first IPCC statement refers to that. The amount of CO2 released each year by humans would raise the CO2 by more than what is measured if all of it stayed in the atmosphere. About 57% of the CO2 disappears. It goes into trees and the ocean and other natural "sinks" that absorb carbon. The amount that stays in the air is called the airborne fraction. This fraction has stayed the same for a long time. WUWT does not understand what the airborne fraction is so they think (incorrectly) that if the fraction stays the same that the CO2 concentration in the air is staying the same. The real issue is that scientists fear that the airborne fraction will increase. If the sinks become full or stop absorbing carbon for some reason then more CO2 will stay in the atmosphere. That means the CO2 concentration will begin to rise much more rapidly. The climate models presume that the airborne frction will not increase so if the fraction increases we are in even more trouble that we currently think. (For example a recent paper estimates that permafrost will release a large amount of carbon starting in 10 or 20 years) This recent skeptical science thread reviews some of the related issues about the carbon cycle. As you learn more it makes more sense and the pieces start to fit together.
94898. Rob Honeycutt at 03:47 AM on 4 March 2011
       Crux of a Core, Part 1b
       Norman @ 13... Read that paper just now. It strikes me as fairly dated already. It's also seems to fall short of being a full paper on temperature reconstruction. They're kind of piecing together various different parts of other papers in order to make a conclusion on holocene temperatures. The conclusion is fairly pedestrian... "Even though there are anthropogenic sources of GHG's such as CO2, climate changes must be judged against the natural climatic variability that occurs on a comparable time scale. The LIA, the MWP, and similar events are this natural variability. These events correspond to global temperature changes of 1-2C. The frequency, rate, and magnitude of climate changes during the holocene do not support the opinion that the climatic changes observed during the last 100 years are unique or even unusual. Recent fluctuations in temperature, both upward and downward, are well within the limits of observed nature." This is hardly news, even in 1999. It's widely accepted that climate changes. It's widely accepted that there are a range of mechanisms that force changes in climate. You have to step back for a moment and consider the alternative position. If we have introduced an additional radiative forcing of ~1.5W/m2 through an enhanced GHG effect (which is widely accepted on both sides of the debate), why would that NOT translate into the increased warming we've seen in the past century? 1) What would be damping the GHG forcing, and 2) What would be the natural mechanism driving the warming? This is why so much money has gone into climate research over the past 2 decades. We have to know if this is real. The conclusion that is coming out in the research is that, we can NOT account for current warming through other natural mechanisms and we are warming the planet through our use of fossil fuels.
94899. JMurphy at 03:43 AM on 4 March 2011
       Ice age predicted in the 70s
       That Climate Depot 'Factsheet' is a nonsense. There are links to newspapers, blogs and books (many repeated or referenced more than once); broken links to the US Senate; and the use of the usual suspects, i.e. IceCap, JohnDaly and Inhofe, as well as such charming sites as AlGoreLied and PeopleForGlobalWarming. The only properly sourced links (three of them at the end) are : A broken one to AMS. One to an AMS paper (which does work) which states : If the actual ratio a/b of most tropospheric aerosols is of order unity, as inferred by previous authors, then the dominant effect of such aerosols is warming except over deserts and urban arms where the effect is somewhat marginal between warming and cooling. (WHERE a/b is "the ratio of absorption a to backscatter b of incoming solar radiation by the aerosol") Suggestions by several previous authors to the effect that the apparent worldwide cooling of climate in recent decades is attributable to large-scale increases of particulate pollution of the atmosphere by human activities are not supported by this analysis. The third link is to a book by Siegfried Fred Singer (!), which goes to a paper by J. Murray Mitchell Jr of NOAA, but which cannot be viewed in its entirety. However, the abstract states : A 32% increase of atmospheric CO2 over 1850 levels is predicted by 2000, causing an estimated 0.6 deg C increase in the global equilibrium temperature. This warming effect may be offset to a certain extent by cooling due to anthropogenic particle loading; in addition, CO2 input is expected to decrease as the consumption of fossil fuels decreases. It is observed that, although there is substantial evidence of global climate trends in the last century, such variations have occurred in the past as the result of natural processes. But even the portion of it that can be viewed from Singer's book states that CO2 is the dominant effect, which could have greater effects in the future, thereby causing warming. And it suggests volcanic ash as the explanation for the cooling from the 1940s. If all of that is proof of a 70s 'Coming Ice Age' claim, it is very poor.
94900. dana1981 at 03:36 AM on 4 March 2011
       Climate Sensitivity: The Skeptic Endgame
       Giles, there are a few individual studies which put climate sensitivity at about 3 +/- 1.5°C at a 95% confidence range, which is also approximately the range adopted by the IPCC. Other studies have larger ranges at that certainty level, but they overlap with the IPCC range. You seem to be arguing that no individual study has a sufficiently narrow range of possible values to convince you. Personally, I think the fact that virtually every study overlaps in this same 3 +/- 1.5°C range using all sorts of different lines of evidence is very convincing. Believing sensitivity is outside that range effectively requires believing that every single study happens to be wrong in the same direction.

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