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actually thoughtful at 08:01 AM on 4 March 2011Putting 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? -
Peter Offenhartz at 07:58 AM on 4 March 2011Roy Spencer’s Great Blunder, Part 3
What a brilliant, thorough and energetic analysis! A LOT of work went into your piece. Thank you! -
dhogaza at 07:55 AM on 4 March 2011Climate 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. -
les at 07:53 AM on 4 March 2011Climate 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. -
thepoodlebites at 07:40 AM on 4 March 2011It'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. -
Eric (skeptic) at 07:28 AM on 4 March 2011Climate Sensitivity: The Skeptic Endgame
Parameter A should read Parameter P above. -
Eric (skeptic) at 07:27 AM on 4 March 2011Climate 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. -
angusmac at 07:21 AM on 4 March 2011Hockey 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):
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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. -
Marcus at 07:01 AM on 4 March 2011Putting 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. -
bbickmore at 06:30 AM on 4 March 2011Roy 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. -
les at 06:25 AM on 4 March 2011Climate 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 -
actually thoughtful at 06:23 AM on 4 March 2011Putting a new finger on climate change
Meant carbon13 vs carbon 12 above. -
actually thoughtful at 06:20 AM on 4 March 2011Putting 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) -
dana1981 at 06:12 AM on 4 March 2011CO2 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. -
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." -
NewYorkJ at 06:00 AM on 4 March 2011Crux 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. -
Daniel Bailey at 05:58 AM on 4 March 2011Prudent 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
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NewYorkJ at 05:58 AM on 4 March 2011Crux 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 -
Albatross at 05:56 AM on 4 March 2011Roy 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. -
dana1981 at 05:47 AM on 4 March 2011Climate 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. -
Gilles at 05:45 AM on 4 March 2011Climate 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. -
Gilles at 05:42 AM on 4 March 2011Climate 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) -
actually thoughtful at 05:34 AM on 4 March 2011Roy 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. -
muoncounter at 05:31 AM on 4 March 2011Climate 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? -
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? -
Dikran Marsupial at 04:47 AM on 4 March 2011Is 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. -
CBDunkerson at 04:39 AM on 4 March 2011Putting 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. -
dana1981 at 04:35 AM on 4 March 2011Roy 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. -
dana1981 at 04:33 AM on 4 March 2011Climate 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. -
Eric (skeptic) at 04:23 AM on 4 March 2011Climate 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. -
Gilles at 04:19 AM on 4 March 2011Climate 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. -
Tshane3000 at 04:04 AM on 4 March 2011Is 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. -
Alexandre at 03:58 AM on 4 March 2011Roy 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. -
Tom Curtis at 03:53 AM on 4 March 2011Crux 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.
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michael sweet at 03:49 AM on 4 March 2011Is 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. -
Rob Honeycutt at 03:47 AM on 4 March 2011Crux 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. -
JMurphy at 03:43 AM on 4 March 2011Ice 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. -
dana1981 at 03:36 AM on 4 March 2011Climate 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. -
Tshane3000 at 03:35 AM on 4 March 2011Is the airborne fraction of anthropogenic CO2 emissions increasing?
The confusion between airborne CO2 fractions and CO2 concentrations--and the significance of each--raises a much larger issue: the generally poor communication of complex scientific subjects to a lay audience. Often the overall meaning and impact of discoveries about complex processes are unclear, or get mixed up with other processes. Along with that, its overall effect on or significance to climate change gets lost in translation. Bottom line: the real, far-reaching and sometimes dire conclusions about various climate-related discoveries often get lost, diluted or distorted. An example: I just learned that ocean acidification has huge negative consequences, which are happening right now and getting worse. But I learned about it accidentally, via research on other topics. There are few or no stories in the media about it now. It is ongoing, it is devastating our oceans--but nothing is out there warning the public to stop fossil fuel use, the main cause of the ocean acid spiking. Consequence 1: This muddiness in scientific communications feeds new skeptic arguments as (perhaps unknowingly false) "bombshells", which then get fed to the public (often in watered down or distorted form) from the media by reporters who don't understand the science enough to question it. Also facts and their significance are misrepresented or distorted by reporters with a political agenda, or a mandate to angle news with a conservative or pro-business bias. Such mandates were revealed in recent Fox News scandals, such as directives to staff to do so on health care reform issues, and others, by heads of Fox News. (See Wikipedia on Fox News Channel.) Consequence 2: Hence, the general skepticism among the public (at least in the U.S.) is far greater than that among scientists in general. Public belief in human-caused global warming (AGW) is hugely less than the 97% of climate scientists who understand (based on the huge piles of evidence) that humans are causing global warming and consequent ecological catastrophes. Consequence 3: When the scientific community gets around to fixing the message, it's not heard--ineffective, too complicated, etc.--or it's too late to squash the new myth, which spreads like wildfire in the blogosphere, via Faux News and of course, conservative talk radio. In some media, nobody seems able or willing to check facts or trust real climate scientists over people without pertinent credentials; some skeptical scientific bystanders and those in fields not related directly to climate science are held up as heroes--based not on the quality of their work, but on their skepticism about climate change causes and processes. Sadly, a large portion of the disillusioned public trusts these skeptics without question. This group is unwilling or unable to discern real science from specious claims, over-hyped objections, weak challenges, and outright lies. They recycle myth after myth, and only the ones that fit their predetermined notions. Not scientific! (Parents and teachers: would you please show kids how to do research thoroughly and think critically!? Even better, learn how yourselves.) Consequence 4: The government has passed many laws, and blocked the passage of far more, that would limit climate change and cut pollution. This is a catastrophic failure to solve the problem--based largely on a cracked foundation of weak, broken or misconstrued scientific messaging! What can be done? It's hard to change political beliefs and alignments much. Many conservatives simply align with other conservative opinion leaders against human-caused global warming, for example, without bothering to check the evidence. But scientists *can* do one thing better: communicate. One solution: Scientists need to work with marketers--hire an ad agency for heaven's sake!--to popularize fact and evidence better than the misinformation (in some cases, disinformation and lies) on global warming. Another solution: reach out to schools. Children are constantly learning science concepts, and the framework is already there to educate them about climate science and climate change. Put the educational materials out there, make it part of the government program to boost science and technology training, and get it done!Moderator Response: Please try and keep your comments on topic, per this site's Comment Policy. You can use the search button or navigation links to find threads related to your point. For this particular post, Are we too stupid would be a more appropriate thread. -
Dikran Marsupial at 03:28 AM on 4 March 2011Is the airborne fraction of anthropogenic CO2 emissions increasing?
The airborne fraction is important as it is an indicator of the ability of the natural environment to resist the rise in atmospheric carbon dioxide. If the airborne fraction increases, this suggests that the oceans and terresrtial biosphere are becoming saturated; should that happen we would have less leeway in our use of fossil fuels as more carbon dioxide will be added to the atmosphere for each unit of fossil fuels consumed. Essentially dC = AF*CAE where dC is the increase in atmospheric carbon dioxide from the pre-industrial equilibrium value of 280ppmv, AF is the arborne fraction and CAE is cumulative anthropogenic emissions. Each year that we emit CO2, then cumulative anthropogenic emissions (CAE) is a little larger, and if AF is constant, then dC will also be a little larger. 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. It is a bit like paying tax. We pay tax on our income at a fixed rate (a bit like the arborne fraction), but the total (cumulative)amount of tax we have paid in our working lives still increases each year. IIRC Watts is confusing airborne fraction with the atmospheric concentration. If the airborne fraction remains constant, that would be a good thing as it suggests the natural carbon sinks have not yet begun to saturate, but it doesn't mean atmospheric carbon dioxide levels (and hence radiative forcing) are not still rising. -
Bibliovermis at 03:26 AM on 4 March 2011Is the airborne fraction of anthropogenic CO2 emissions increasing?
Airborne fraction is not the same as atmospheric concentration. It is defined as the ratio of the annual increase in atmospheric CO2 to the CO2 emissions from anthropogenic sources. I apologize for not providing any references, as this is being tapped out from my phone. -
Mike Palin at 03:18 AM on 4 March 2011Roy Spencer’s Great Blunder, Part 3
Barry- This is an outstanding step-by-step analysis of Spencer's mistakes. I was initially a bit confused about Fig. 10. It might help for comparison purposes to add a reconstructed temperature anomaly curve - even the erroneous one Spencer prefers. Your points about the nature and practice of the scientific enterprise in the final few paragraphs are spot on IMO. Well done! -
Tshane3000 at 03:10 AM on 4 March 2011Is the airborne fraction of anthropogenic CO2 emissions increasing?
Even though I have researched climate change/global warming in depth for a few years, there are many aspects of the science I don't understand. I grasp the issues, I see the political problems of business fighting scientists for control of the economy and its direction, based on the cost of going to a low- or zero-carbon economy vs. the dire ecological (and some economic) trade-offs of business as usual. But I need help on much of the science--especially its significance to the earth's ecosystem. As a lay person, I don't see the significance of the airborne fraction of CO2 being relatively constant. Why does that matter to some (Anthony Watts, for example), but not to you or RealClimate.org? No website I've searched has explained this. Please put the answer up front and center in the blog--because how this affects our ecology is why I care. The airborne fraction findings appear to conflict with the IPCC AR4 statement: "Atmospheric carbon dioxide (CO2) concentration has continued to increase and is now almost 100 ppm above its pre-industrial level." Yet a few lines later IPCC AR4 states: "There is yet no statistically significant trend in the CO2 growth rate as a fraction of fossil fuel plus cement emissions since routine atmospheric CO2 measurements began in 1958. This ‘airborne fraction’ has shown little variation over this period." Confusion alert! Explain this conflict to non-scientists if you want us to understand. How can CO2 concentrations be rising since the 1850s (up to 390s ppm as of Dec. 2010) if the airborne fraction is constant? It seems obvious that the airborne fraction would be rising as concentrations of CO2 rise. "Airborne fraction" sounds the same as "concentration." Concentration is a "fraction"--right? Measured in parts per million (ppm). How can concentrations of CO2 be rising if the fraction is constant? Conversely, if concentrations are rising, how could the airborne fraction stay the same? The airborne fraction should be rising as well. Note: It's easy to see why some bloggers are confused about the CO2 measurement site (Mauna Loa, Hawaii), and assuming (wrongly) that CO2 concentrations are only rising there from volcano gas. (You cover this objection well elsewhere on the site.) Is this the reason Watts jumped on the Knorr study--confusion about the significance of the airborne CO2 fraction? Please, make the answer so simple a 4th grader can understand it.Moderator Response: [Daniel Bailey] The natural carbon cycle is a closed system. Humans are adding extra CO2 into it. The airborne fraction is how much the system can deal with & remove (currently about half of the extra CO2 we put into it). What is left undealt with is added to the existing level of CO2 in the air. This second value is the concentration. Higher levels of CO2 act to raise the global temperatures over time, until a new equilibrium is reached. All other contributing factors being equal, if CO2 concentrations are rising, so will global temps. -
garythompson at 02:46 AM on 4 March 2011Crux of a Core, Part 1b
My apologies for pasting the wrong link to my post in #11. the correct graph is here:
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les at 02:25 AM on 4 March 2011Climate Sensitivity: The Skeptic Endgame
64 ericThe model results form a "probability distribution" only in the narrow sense of a series of random runs. But perturbing parameters is not probabilistic,
Could you explain your problem with this technique? It is not an uncommon practice (in many disciples) to perturb parameters of models when those parameters are either not known precisely and/or when they can naturally vary over a range. One then calculates the log-likelihood (note likelihood here is a statistics technical term) distribution to estimate the set (or sets) of parameters which best fit the facts, given measurement error distributions or to give the support function (maximum likelihood) for the model. No? -
KR at 02:13 AM on 4 March 2011Climate Sensitivity: The Skeptic Endgame
Gilles - "Concerning Hansen's study, I will first ask a question : do you have an idea of the magnitude of the annual variation of solar forcing between June and December..." This is a complete non sequitur to the Hansen paper, which concerns total forcings and responses over 100's of thousands of years, not annual variations. Side note: While I find the Hansen ocean cores and the scalings thereof a bit new (to me), and would like to see some more supporting evidence as to their correlation with ice cores, factors of depth and location, etc., it's a good paper, and worth looking at. So, Gilles - annual temperature variation vs. the Hansen paper is a complete red herring. You appear to be trying to side-track the discussion. -
Gilles at 02:07 AM on 4 March 2011Climate Sensitivity: The Skeptic Endgame
mucounter : I think the evidence is pretty well displayed on figure 2. I don't know any physical quantity whose measurements differing by a factor two or more would be said to "agree" , do you ? 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. For obvious reasons : if I add "wrong" models to the sample, giving much higher o smaller sensitivity, the "likelihood" of all others, including the true one (if any), will decrease. Well that's kind of weird isn't it ? how can the validity of a true model decrease if I add BS to the sample ? so please tell me : how exactly is chosen the sample on which you compute this "likelihood" ? -
Kevin C at 01:09 AM on 4 March 2011Roy Spencer’s Great Blunder, Part 2
Thanks Dikran for pointing that out. In fact, the entire paragraph added little to the point I was making and will distract from it for some readers - my point would be improved by deleting it if you feel inclined. Sorry for the inconvenience. If I may expand: There's a huge can of worms concerning communication which I think needs discussing, and I'm not sure where the discussion should take place. I've barely begun to scratch the surface. Can I illustrate by some questions: 1. Who is SKS speaking to? How does that affect the form of communication SKS should adopt? (Has this question even been asked? Or did it happen the other way round: The form of communication - NPOV academic with lay summaries - was chosen and the resulting audience was a unplanned consequence.) 2. Who is Barry speaking to? To Roy Spencer, to people who have read his book, or to people who might encounter people who have read his book? How does that affect the form of communication? 3. Who are the contrarians and what are their motivations? How do we best communicate to different contrarian groups? Which groups are most accessible to persuasion? (As an illustration, communicating to someone who regards themselves as a rational skeptic who has made a reasoned rejection of a consensus view is very different to someone whose views are derived from a political ideology, or someone whose views are determined by the need to conform to a peer group. In the last case, changing someone's mind might destroy their social network - a hard challenge). There appears to be an active sociological and cultural anthropological academic literature on these issues. 5 mins with google pulled up these: http://www.stanford.edu/group/CCB/articles/Anderegg_ClimateConsensus_Report2009.pdf http://www.carleton.ca/isema/documents/editions/ISEMAFall2006.pdf#page=10 http://pus.sagepub.com/content/16/2/223.short I don't even know where to start, and if I were to do so the sociologists would rightly be laughing at me and whispering 'Dunning Kruger' to one another. What I'd really find useful is some articles, possibly be sociologies/social anthropologist writing in lay terms, on understanding who the different groups are skeptics are and how they are being so successful in communicating a message. Also what forms of communication are open to us and how to chose between them.Moderator Response: No problem, your mention was fine as it was only an illustrative aside. -
Eric (skeptic) at 00:53 AM on 4 March 2011Climate Sensitivity: The Skeptic Endgame
I believe that error bars and probability distributions can be misleading in the context of sensitivity. Looking at fig 3 in the Knutti paper, I see two lines of evidence: models and paleoclimate. The paleoclimate evidence has red boxes for "similar climate base state", IOW it doesn't apply to today's interglacial climate. An error bar or a probability distribution doesn't capture that fact, only the red box does. The second type of evidence is models, as discussed in the models section in the paper: "Different sensitivities in GCMs can be obtained by perturbing parameters affecting clouds, precipitation, convection, radiation, land surface and other processes". In the section Constraints from the Instrumental Period, the authors say that the tenperature response to fast forcings has a nonlinear response to climate sensitiity and thus can be only verified by validating the models. The model results form a "probability distribution" only in the narrow sense of a series of random runs. But perturbing parameters is not probabilistic, those perturbations are either correct or not. So a broader probability distribution or an error bar is simply not possible.
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