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Tristan at 06:04 AM on 9 February 2012Still Going Down the Up Escalator
DB Absolutely, that's what I thought and why I checked. I wanted to alert him to a connection to his moniker in case he didn't know about it. -
John Hartz at 06:03 AM on 9 February 2012Michaels Misrepresents Nordhaus and Scientific Evidence in General
Technical note: The font size of the text in this OP is larger than the one normally used in SkS articles. -
Tristan at 05:40 AM on 9 February 2012Michael Mann, hounded researcher
Say I wanted to be able to evaluate the claims made in MM03. How big a project is that? Years or weeks? -
Rob Painting at 05:35 AM on 9 February 2012Medieval Warm Period was warmer
jzk - "I could take Mann's data from the MWP and produce that global chart based on 950 to 1250. Then I could produce another chart with the same data, but only 980-990. Then, I could put them next to each other. One would be all red, and the other would be all white" This is the point I made earlier, although not clearly enough, you cannot do this because the proxy data with sufficient global coverage and resolution (detail at the annual level) does not exist. For the instrumental record we have millions of measurements made all over the world for the last 130-odd years. These have great precision because they were made by thermomemeters, on (mostly) a daily basis. Even then great care has to be taken to ensure spurious signals, and therefore bias, doesn't creep into the record. In the MWP thermometers had not yet been invented so we have to rely on signatures of global temperature embedded in ice cores, tree-rings, coral growth rings, sediment deposits, pollen, cave stalagmites/stalagtites (speleotherms) etc. Not all of these signatures (proxy data) have resolution at the annual scale, most are only indicators of local temperature, they are affected by other factors which have to be zeroed out, and virtually all of them are not complete. They only cover a small interval over the MWP. The purpose of the statistiscal analysis by Mike Mann and others is to combine all this data so as to give an idea of what global temperature was back then. That means weighting the data and putting them into a common reference frame relative to each other. That way you can allow for the fact that the data do not overlap, and have different time resolution, and are only indicators of local conditions. So what you ask cannot be done. -
Utahn at 05:17 AM on 9 February 2012Michaels Misrepresents Nordhaus and Scientific Evidence in General
Well said. Its amazing, almost any claim I've seen Michaels make is a distortion of the truth when you actually go to the source... -
dana1981 at 05:15 AM on 9 February 2012Michaels Misrepresents Nordhaus and Scientific Evidence in General
Also note that Nordhaus is one of the most conservative economists when it comes to estimating the costs of climate change, i.e. see here and here, and nevertheless supports putting a price on carbon emissions. -
jzk at 05:14 AM on 9 February 2012Medieval Warm Period was warmer
"Also, "...to a peak of warming". Really? On what basis do you claim that current temperatures are a peak? All available evidence indicates that they are just a spot on a continuing upward slope." CB, Peak so far. If temperatures continue upwards, then it would be fair to redo the graph. Then, there would be a new "warmest" decade to use. Compare the warmest decade currently to the warmest decade in the MWP. Using Mann's data would still yield your desired result that the MWP was cooler than today, but it would be doing it in a fair presentation of the data. The comparison in the charts presented is meaningless. As I stated, I could show the same thing by comparing any time period to a shorter time period contained in itself. What would that show? Nothing. -
dana1981 at 05:13 AM on 9 February 2012Michaels Misrepresents Nordhaus and Scientific Evidence in General
Nice post Alex. You just have to shake your head when the fake skeptics insist their (mis)interpretations of the climate science/economics literature are correct, and the scientists' interpretations of their own work are wrong. Nordhaus has supported a carbon pricing system for decades, and it's a gross misrepresentation to use his work to argue against such a system. -
jzk at 05:10 AM on 9 February 2012Medieval Warm Period was warmer
Composer99, Mann didn't take his chart and compare it to 1999-2008, skeptical science did. -
CBDunkerson at 05:02 AM on 9 February 2012Volcanic Influence on the Little Ice Age
owl905, you seem to be unable to differentiate between things that you (for whatever reason) assume I meant and what I actually meant (and/or said). This makes meaningful communication effectively impossible. -
owl905 at 04:54 AM on 9 February 2012Volcanic Influence on the Little Ice Age
@CB - your response doesn't match your original claim. And your response indicating that I either agree or disagree with Miller is untrue - I disagreed with your statement that the volcanic effect lingered for centuries. As for evidence that supports a better interpretation, read Mann - "does not require a solar trigger", but probably still requires that notorious weaker solar source. And that is not a feedback. And it makes a mess of the 'self-sustaining' phrase. Also note that Mann's paper shows no 'four super-eruptions' in the 1375-1400 interval, and the graph posted by muoncounter properly shows a real possibility from the mystery 1458 timeframe. -
Composer99 at 04:33 AM on 9 February 2012Medieval Warm Period was warmer
jzk: The historical instrumental temperature record (those graphs of NASA GISS, UAH, HadCRUT, and the like) are compared to an arbitrarily defined 30-year climatological baseline period in order to clarify temperature anomaly information. I am not aware of any serious valid criticism of this practice. As long as the uncertainties and caveats due to proxy data (the differences in practice) are made clear in the applicable literature, is there some appreciable difference, in principle, between this standard practice and what has been done in Mann et al 2009 with regards to the Medieval Climate Anomaly? -
CBDunkerson at 04:14 AM on 9 February 2012Medieval Warm Period was warmer
jzk, again... the claim that the several hundred year MWP was warmer than current temperatures comes from skeptics. SkS showing a graphic proving that claim false is thus perfectly reasonable. Rather than complaining here about a graphic disproving the claim, perhaps you should be instructing 'skeptics' on how to make less ridiculous arguments. Also, "...to a peak of warming". Really? On what basis do you claim that current temperatures are a peak? All available evidence indicates that they are just a spot on a continuing upward slope. "Compare the warmest decade of the MWP to the warmest decade now. That would be a fair comparison" It would not be the comparison that 'skeptics' constantly make and it is not possible with current data. We do not have sufficiently detailed geographic and temporal data to create a map of (or even conclusively identify) the warmest decade of the MWP. Though again, I find it odd that you suggest that the peak of the MWP should be compared to the not-peak of the current warming to be 'fair'. Surely, if we were really trying to determine whether modern warming is within the range of natural variability (as claimed) we should compare the peak of the MWP to the eventual future peak of the modern warming, no? -
Tom Curtis at 04:11 AM on 9 February 2012Medieval Warm Period was warmer
jzk @58: "I just want to promote good science" No, you want to apply a cooky cutter standard without any understanding of context or purpose. Such "cooky cutter standards" cannot exist in real life, except as reduced to basic principle: 1) Do not present false information; 2) Do not make unjustified inferences; and 3) Always let readers know what you have done, so that they can check it for themselves. If you want to argue the article represents bad science, you have to engage with the argument in the article and show how it is unjustified based on available evidence. Failing to do that, at best you can show that there are people out there easily confused by a misunderstanding the author failed to consider (possibly because it is so obviously an unjustified inference). -
Tom Curtis at 04:04 AM on 9 February 2012Medieval Warm Period was warmer
jzk @56, your claims are unjustified. To begin with, Mann et al 2009 make exactly the sort of comparison you claim to be unjustified. Specifically, figure one (intermediate article above) is a comparison of temperatures over a three century period in the Middle Ages to a thirty year period in the twentieth century. With a bit more work, John Cook could have compressed his two figures (from Mann et al 2009) into one by showing the MWP compared to a 1999-2008 baseline. Clearly, therefore, there is no inprinciple difference between Cook's comparison and the data presentation in the original graph. If there were any merit to your claim that such comparisons are bad science, then you must reject that chart itself for not (impossibly) choosing a three century baseline in calculating the anomalies. As it stands, I suspect editors and reviewers of Science Magazine know a little about what constitutes good and bad science. They appear to have judged this comparison of a three century interval with a thirty year interval good science for the very simple reason that, without such comparisons the mean temperature cannot be differences cannot be shown at all. That is something you should consider seriously. Without the sort of comparison, which you in a now deleted post called "absolute fraud" the information in the anomaly map could not have been presented at all. So yours is a standard which amounts to censorship of the data. The question with a diagram in science is always only three things: Does the diagram accurately present the information collected by the study; do the inferences drawn from the information in the graphic actually follow from that information; and is the graphic presented in a way that avoids confusion. On these three counts, nothing prevents a comparison of three centuries data to a single decade. What is necessary for such a comparison is that the conclusions be appropriately restricted, and that the data be presented in such a way as to avoid unwarranted conclusions. On the first point, (accuracy of information) there is no question; on the second, as the unwarranted inference you are making is not made by either Mann et al, nor John Cook there has yet to be shown a problem. On the third point, I believe that a caution to the effect that the data presented does not show that all decades within the MWP where cooler than the 2000s. But that is not a question of poor science, but of poor presentation. -
jzk at 04:03 AM on 9 February 2012Medieval Warm Period was warmer
"a graphic comparing temperatures over those two time periods seems a perfectly reasonable response." CB, But that is not what you did. You compared several hundred years that contained both warming and cooling to a peak of warming. That is no comparison at all. Compare the warmest decade of the MWP to the warmest decade now. That would be a fair comparison, and if you used Mann's data, it would still confirm your case which seems to be, "yeah some warming then, but not as much as now." I just want to promote good science. -
CBDunkerson at 03:53 AM on 9 February 2012Medieval Warm Period was warmer
jzk, given that false claims that 'the MWP was warmer than current temperatures' are made on a regular basis, a graphic comparing temperatures over those two time periods seems a perfectly reasonable response. Yes, in an ideal world we would be able to tell the deniers, 'comparing multiple centuries to a few years is "meaningless and bad science"' and they would shut up and go away. This is not an ideal world. Instead, we present a direct comparison of the exact things they cited. If they want to change their claim to 'some decade in the MWP may have been warmer than the past decade' we can switch to pointing out that all available evidence suggests otherwise. Until then I really don't see the problem in providing direct evidence that the claim they are making is false. -
muoncounter at 03:36 AM on 9 February 2012Volcanic Influence on the Little Ice Age
A new discussion of the 'missing' volcano just popped up. Well-illustrated and sourced, including a figure from the new Mann paper.
It sure looks like these coolings are short-lived transients.
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Dikran Marsupial at 03:18 AM on 9 February 2012Still Going Down the Up Escalator
piratelooksat50 From a statistical and scientific perspective there is no fuss, it is all really quite straighforward. The fuss arises when those who don't understand the science and/or statistics argue that climate change has stopped [or other such claims] on the basis of the lack of statistically significant warming over a timescale to short to expect a statistically significant trend whether the climate was warming at the expected rate or not. It is very much the purpose of SkS to point out such canards, and explain why they are specious. The escalator diagram is a very good example of this. -
MangoChutney at 03:18 AM on 9 February 2012Volcanic Influence on the Little Ice Age
@dana1981 #13 Thank you dana, this is as I thought and I agree "if this theory is correct". -
jzk at 03:07 AM on 9 February 2012Medieval Warm Period was warmer
Tom, "There is, however, some justification for it in this instance." While you may have evidence to suggest that the MWP was not that warm, that warming will continue, that the decade chosen will turn out to be a cool decade, or anything else related to this issue, comparing those two charts is meaningless and bad science. That is my only point. In fact, it detracts from the real case that you are making because it appears to be manipulation. -
apiratelooksat50 at 03:06 AM on 9 February 2012Still Going Down the Up Escalator
Personally, I don't see what all the fuss is about. There are obviously periods of cooling trends (depending on the date range chosen), but overall the trend is rising (since the start date chosen). Skeptic or believer, it's as plain as the nose on your face. -
Tom Curtis at 02:57 AM on 9 February 2012Medieval Warm Period was warmer
jzk 54, a comparison between a single decade and several centuries is far from ideal. There is, however, some justification for it in this instance. In particular, very solid evidence suggests that this will be the coolest decade of the next several centuries. (How many depends on just how soon we break the fossil fuel habit.) That being the case, we know that the average global temperature over the next few centuries will be higher than that for the current decade, and hence higher also than the average over the several centuries of the MWP. In other words, the comparison does strongly suggest that the current warming will result in greater overall warmth in this century than at anytime in the MWP. Of course, it is not appropriate to look at a decade to century comparison and conclude that this decade is warmer than any decade in the MWP. However, a large number of studies have been done which suggest exactly that. It is more likely than not, on current evidence that this decade, and even the 1990s was warmer than any decade in the MWP. However, the evidence for that is not so strong that it can be stated categorically. -
dana1981 at 02:52 AM on 9 February 2012Volcanic Influence on the Little Ice Age
Yes, the Maunder Minimum would have effectively amplified the volcano and feedback-caused cooling, if this theory is correct. However, the notion that we're just 'recovering' from the LIA is faulty, because we're currently warming much faster than the MWP warming or LIA cooling, and volcanoes and solar activity have had little influence over that warming, especially over the past ~50 years, as we showed here. -
jzk at 02:48 AM on 9 February 2012Medieval Warm Period was warmer
Rob, Let me put this another way. I could take Mann's data from the MWP and produce that global chart based on 950 to 1250. Then I could produce another chart with the same data, but only 980-990. Then, I could put them next to each other. One would be all red, and the other would be all white. Could I make the claim "The MWP was warmer than the MWP?" How is that a helpful comparison? Again, none of what I say contradicts the premise that the MWP was cooler than today, just the way that the charts are used to illustrate that position. -
MangoChutney at 02:46 AM on 9 February 2012Volcanic Influence on the Little Ice Age
@muoncounter #11 If volcanic eruptions were the start of the LIA, as has been suggested, wouldn't the Maunder Minimum, which occurred midway through the LIA, just have exasperated the cold period started by erupting volcanoes? -
Dikran Marsupial at 02:34 AM on 9 February 2012Global Warming: Trend and Variation
Tom & CBDunkerson - great minds think alike! ;o) As I said, sea level observations are not my forte, but even I knew that station data are not a reliable indicator of global sea level when taken in isolation and that there were good reasons for this. I also knew that Google Scholar is a handy way of investigating whether an argument has some merit to it before I use it. -
CBDunkerson at 02:29 AM on 9 February 2012Global Warming: Trend and Variation
Disclaimer: Tom Curtis and I are not, in fact, sharing the same brain. Any similarities between our postings, choice of papers to cite, and/or wording (e.g. 'random conspiracy blog' / 'random internet guy') are purely coincidental. -
Tom Curtis at 02:11 AM on 9 February 2012Global Warming: Trend and Variation
Dikran Marsupial, Captain Ross's benchmark at Port Arthur was examined by Pugh et al, 2002. Based on that, they conclude that sea level at Port Arthur has risen 0.13 meters in the interval, or 0.8 mm per year. Fred Staples want to ignore the peer reviewed literature because some random internet guy says he should. As I understand it, here at SkS "some random internet guy" is not considered an authority. That being the case, it is up to Staples to both present the information from Pugh et al (without cherry picking), and to show why Pugh et al's conclusion is wrong. As it stands, Staples has not bothered to do that, and does not even bother reporting accurately the random internet guy who is his source. Specifically, as quoted by John Daly,""My principal object in visiting Port Arthur was to afford a comparison of our standard barometer with that which had been employed for several years by Mr. Lempriere, the Deputy Assistant Commissary General, in accordance with my instructions, and also to establish a permanent mark at the zero point, or general mean level of the sea as determined by the tidal observations which Mr. Lempriere had conducted with perseverance and exactness for some time: by which means any secular variation in the relative level of the land and sea, which is known to occur on some coasts, might at any future period be detected, and its amount determined. The point chosen for this purpose was the perpendicular cliff of the small islet off Point Puer, which, being near to the tide register, rendered the operation more simple and exact; the Governor, whom I had accompanied on an official visit to the settlement, gave directions to afford Mr. Lempriere every assistance of labourers he required, to have the mark cut deeply in the rock in the exact spot which his tidal observations indicated as the mean level of the ocean."
As can be seen, Ross had not reason to believe Port Arthur was particularly stable, and such a belief did not enter into his reasons for placing the benchmark there. As an aside, I suspect his reporting of Einstein is no more accurate than his reporting of Captain Ross. An google search of his quotation shows that Fred Staples is the only person on the internet who quotes it. -
CBDunkerson at 02:03 AM on 9 February 2012Global Warming: Trend and Variation
Or, rather than reading the ramblings of conspiracy theorists on some random blog, we could look at what the peer reviewed scientific literature says about the Capt Ross sea marker in Tasmania; "Observations of sea level at Port Arthur, Tasmania, southeastern Australia, based on a two-year record made in 1841–1842, a three-year record made in 1999–2002, and intermediate observations made in 1875–1905, 1888 and 1972, indicate an average rate of sea level rise, relative to the land, of 0.8 ± 0.2 mm/year over the period 1841 to 2002. When combined with estimates of land uplift, this yields an estimate of average sea level rise due to an increase in the volume of the oceans of 1.0 ± 0.3 mm/year, over the same period." The amount of sea level rise varies across the globe due to effects of gravity, fluid dynamics, land uplift, and other factors. However, given that the volume of water in the oceans is increasing (due to both ice melt and thermal expansion) the long term trend is upwards... everywhere. Including this site in Tasmania. -
Composer99 at 01:53 AM on 9 February 2012Global Warming: Trend and Variation
Fred: Sorry, that's still cherry-picking. Anecdotes from television shows, quotes from famous scientists, and measurements from a single site do not refute the aggregate of tidal gauge and satellite data showing mean global sea level rise is occuring. After all, those are all, by your own standard, observations, and each singly would be enough, by your own standard, to refute a claim that global sea level is not increasing. -
Dikran Marsupial at 01:45 AM on 9 February 2012Global Warming: Trend and Variation
BTW Fred, have you performed a Google scholar search to see if you can find out whether Australia [provides] An Unstable Platform for Tide-Gauge Measurements of Changing Sea Levels or not? If it doesn't provide a stable platform, perhaps that explains why the Tasman sea tide-guages may not give a reliable indicator of global sea levels. -
Dikran Marsupial at 01:36 AM on 9 February 2012Global Warming: Trend and Variation
Fred Staples Einstein was perfectly correct. However the the observation of sea level at one location does not refute the hypothesis that sea levels are rising or that AGW is occuring. To see why, you need to look into both the observations and the physics in more detail. Firstly not every location is a good place to cite a tide guage, because there are other factors that affect the measurements, such as glacial rebound, silting, tectonic movements etc. Also sea level does not rise uniformly around the globe (water is a viscous liquid, the distances involved are large and evaporation is not the same everywhere), so you need to take an average over multiple tide guages, preferably ones located in geologically stable locations. Which is what the scientists actually do. Was Captain Ross a geologist? Did Captain Ross have the scientific understanding of sea level that we have now? No. He was right about taking the measurements, they are indeed interesting and useful, but that doesn't mean you can ignore the wider context. If it was O.K. to pick a single data record and base your argument solely on that, why shouldn't I pick temperatures at some high Arctic station to show that global temperatures were rising very sharply? Simply because it would be a cherry pick, and would be neglecting the broader picture. What is sauce for the goose is sauce for the gander. What you are doing is equally unreasonable. The difference is that I know it is a cherry pick and wouldn't use it as the basis for a serious argument. -
Fred Staples at 01:23 AM on 9 February 2012Global Warming: Trend and Variation
Cherry Picking? As Einstein said, “10000 observations may support a theory, it only takes one to refute it”. Science works like that. After all, the millions of stars seem set in their courses. Navigators use them every day. The earth is clearly at the centre of the universe and every thing revolves around us. Would you let a few wandering planets, and some indistinct moons, refute so well established a theory? Captain Ross marked that sea level because it was the most stable land he knew with the least tidal rise and fall. He thought future generations would be interested. Now you have a theory that human CO2 emissions will cause dangerous sea level rises. If you wish to retain that theory, you are required to explain why it has not happened in the Tasman Sea. While you are about it, you can explain the Comment from the President of the Maldives Federation on the Today programme a year or so ago. He was complaining that his entire country would be inundated if CO2 emissions continued to rise. John Humphreys asked how much the sea levels had risen so far he replied, “about a centimetre”. -
muoncounter at 00:25 AM on 9 February 2012Volcanic Influence on the Little Ice Age
Mango#9: No and no. It's still not established that the LIA was caused by volcanic eruption - especially if no one can point to which volcano erupted at what time. Nor can we suddenly leave out the Maunder minimum entirely. As for 'we could cancel the LIA,' what do you mean? The very existence of the LIA, whatever its causes, shows there is not just one long warming. Even if that were so, why would the modern warming be at a more rapid pace? -
CBDunkerson at 00:16 AM on 9 February 2012Volcanic Influence on the Little Ice Age
owl905, I don't know if we are having some sort of semantic breakdown or if you really believe things to be exactly the opposite of my understanding. The Miller 2012 paper absolutely does suggest that volcanic eruptions caused cooling, which in turn was amplified by climate feedbacks, which resulted in the centuries of cooler temperatures generally known as the LIA. I mean, the bloody title of the paper is, "Abrupt onset of the Little Ice Age triggered by volcanism and sustained by sea-ice/ocean feedbacks". If you disagree with the above then you are going to need to explain what you think the Miller paper is about. If you don't have some radically different understanding of the paper then you must somehow be reading my original post to mean something other than what I said above. At which point I'd suggest that, as a general principal, it would be wise to consider all possible meanings of words and phrases you read and then not assume that interpretations which conflict with reality were the ones intended. -
jzk at 23:49 PM on 8 February 2012Medieval Warm Period was warmer
Rob, I refer only to the two chart chosen by Skeptical Science to contrast todays warming with the MWP. The Mann chart shows a several hundred year period that includes, according to his data, both years of warming and years of cooling. The Skeptical Science chart shows only a decade at a warming peak. It is it any wonder one shows "red" and the other not? It may very well be that the MWP was cooler than today, or not. Let the science show us that. -
MangoChutney at 23:23 PM on 8 February 2012Volcanic Influence on the Little Ice Age
If the LIA was caused by erupting volcanoes and we could cancel out the LIA, is possible that the current warming is just one long continuation of the Medieval Warming Period, Roman Warming Period, all the way back to ..... ? -
Tristan at 22:48 PM on 8 February 2012Still Going Down the Up Escalator
Interesting! BTW DM, is your identity 'outed', or was it something you never bothered to hide?Response:[DB] As a general note, when an individual uses a "nom de plume" rather than their actual name, that decision is to be respected. Period. This is irregardless of whether or not other indiviuals behave less respectfully and then "out" that individual. I'm sure that you'd agree that sharing of personal, privileged data without the express consent of the source of that information is wrong.
Please treat it no differently than the acquisition of stolen (intellectual) property.
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Dikran Marsupial at 21:54 PM on 8 February 2012Still Going Down the Up Escalator
In case anyone is interested, I tried recomputing the credible interval on the regression taking into account the stated uncertainties in the estimates of GMST provided by BEST (I didn't use the last two values due to the lack of coverage of the stations used). Here again is the Bayesian regression analysis using the estimates themselves:
Here is the Bayesian regression analysis taking into account the uncertainty in the BEST estimates.
As I suspected, the 90% credible interval is a little wider, but the difference is barely detectable, which suggests Brigg's criticism of the handling of uncertainty is not much of a cause for concern.
The expected trend for the BEST estimates is 0.0257 (95% credible interval 0.0048 to 0.0464) and when the uncertainties in the estimates are accounted for it becomes 0.0255 (95% credible interval 0.0026 0.0486). Note that the credible interval does not include zero or negative values whether the uncertainty is accounted for or not.
Technical note: The Bayesian regression is performed by sampling from the posterior distribution of regression parameters (including the variance of the noise process). To incorporate the uncertainty in the estimates, I just sampled from the distribution of the responses assuming that the BEST estimate is the mean and the stated uncertainty is the standard deviation (RATS, reading the documentation it is the 95% confidence interval, so it is actually twice the standard deviation, so my analysis overstates the uncertainty by a factor of two - and it still doesn't make much difference!).
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Rob Painting at 19:51 PM on 8 February 2012Medieval Warm Period was warmer
And as if to complicate the situation once again - Last Millennium Climate and Its Variability in CCSM4 - Landrum (2011) suggest something else again. -
Ari Jokimäki at 19:47 PM on 8 February 2012New research from last week 5/2012
One difference with Younger Dryas seems to be that Younger Dryas event might not have occurred globally at the same time (Antarctica seemed to be warming when Northern Hemisphere cooled). -
Doug Mackie at 18:57 PM on 8 February 2012Major Study of Ocean Acidification Helps Scientists Evaluate Effects of Atmospheric Carbon Dioxide on Marine Life
Not quite William. Buffering describes the process by which additions of acid and/or base cause minimal pH changes to a solution (compared to if the acid and/or base had been added to an unbuffered solution).* When oceanographers refer to alkalinity** they mean the acid neutralising capacity of the water with respect to pure carbonic acid (H2CO3). That is, you use H2CO3 as your base unit. It is sort of like currency trading and referencing everything to the $US. Seawater is not usually thought of as a multi-buffered system. Yes, there are other things that function as buffers but they present at low levels and generally poorer buffers; buffering is thus dominated by the carbonate system.*** As for measuring alkalinity, it doesn't really matter what you measure: As we detailed in our OA series (see the button, left side, main page) the CO2 system can be fully described (i.e. calculated) from any two of pH, total alkalinity (AT), pCO2, and total dissolved carbon dioxide (CT). Researchers thus can freely convert between any of those parameters. It comes down to the particular apparatus used. For example, AT and CT are easily measured with good precision and good accuracy but require discrete samples – as opposed to continuous measurement like using a pH electrode. (See the OA series for more on this). *The mechanism by which this is achieved is really cool and we'd be dead without our carbonate buffered blood. The details are senior high school chemistry and if there is sufficient interest I will write up a post about it and try simplifying. **There are several shades of 'alkalinity', including 'total alkalinity'. In the interest of brevity, I am going to concatenate them all here but in later posts I will be more precise. ***Details of this are enchantingly subtle and complex. Read the OA series and come back with questions. -
owl905 at 18:18 PM on 8 February 2012Volcanic Influence on the Little Ice Age
@KR-No idea what your response is about - dropped years is years without rings = missing rings (Mann even uses the term p.3). Your statement about tree-line is straight off both RealClimate and the Mann paper. Dana introduced the Mann paper, so it is part of this thread. And no, it's not "quite frankly unrelated". Both papers focus on different aspects of the forcing effect and timing of volcanic events. Miller's case is boosted if Mann's suggestion of a stronger forcing effect is true. As for the "language you seemed concerned about", no again. It's Mann that's putting up the warning flags not too leap too far too fast with the suggestion. Part of Mann's requirement is to find other tree-types in the same region as controls. -
Bernard J. at 18:13 PM on 8 February 2012Hiding the Incline in Sea Level
...that it would have... -
GillianB at 17:16 PM on 8 February 2012Global Sea Level Rise: Pothole To Speed Bump?
Thanks for this. I didn't realise that sea levels would vary with El Nino and La Nina. It makes sense. -
Rob Painting at 16:31 PM on 8 February 2012NASA scientists expect more rapid global warming in the very near future (part 2)
Muon - here's a couple of papers: Response of global upper ocean temperature to changing solar irradiance - White 1997. Who state: "For penetration depths of 80-160 m(etres) observed in this study, back radiation anomalies come into balance with solar insolation anomalies over equilibration timescales of approximately 1.5-3 years, yielding model phase lags of 40°-75° that are similar to those observed"
And:
Temperature responses to spectral solar variability on decadal time scales - Cahalan (2010). Whom write:
"We find surface atmospheric response ∼1 K, about twice as large as the mixed layer response. The surface air response lags the TSI variation by ∼1 month, while the ocean mixed layer response lags the surface air response by ∼2 years for both in‐phase and out‐of‐phase SSI (spectral solar irradiance) forcings."
No doubt there's a great deal more literature on this, but that's the extent of my search. No real surprise here, scientists from NASA are right about the ocean thermal lag, and people on the internet are wrong.
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chirhophoros at 16:18 PM on 8 February 2012New research from last week 5/2012
A very well assembled compilation - it's great being able to have a look at the papers minus a pay wall. Wrt Lundqvist et al, Does anyone have any idea to what extent the 19 -20 century warming shift resembles or differs from the apparently abrupt termination of the Younger Dryas? CC -
Rob Painting at 15:35 PM on 8 February 2012NASA scientists expect more rapid global warming in the very near future (part 2)
Don 9000 & Pirate - I've received a reply From Dr Hansen, he does not consider that the omission of "implies" changes the meaning of that passage. And as Pirate points out, Dr Hansen is revising the paper anyway. -
Volcanic Influence on the Little Ice Age
owl905 - Mann's paper is about accounting for 'dropped years' from minimal/no growth at marginal tree environs. The trees chosen for tree-ring paleo data are deliberately in marginal regions so that they more clearly show the effects of temperature, rather than fertilizer, local bear populations, insect infestations, etc. In other words, the Mann paper is about improving the time accuracy of tree-ring data. The Miller et al paper discussed in this thread, on the other hand, is about considering an ocean circulation tipping point caused by a series of strong volcanic eruptions, leading to the LIA period lasting hundreds of years. That's a different question entirely, and quite frankly (aside from year-resolution of tree-ring data) unrelated. Identifying the volcano(s) would be very interesting, although they did not show much data for that other than the near-equatorial location due to both hemispheres being affected. The Mann paper is quite interesting - and the language you seem concerned about (your "...warning flag" comment) is entirely reasonable for an initial effort that should be followed up with additional work.
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