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Rob Honeycutt at 04:25 AM on 30 July 2012Climate Change Cluedo: Anthropogenic CO2
Okay gang... Here is the guy's response to Tom's comments. "1st, I see that Mr.Curtis confirmed my point that lower C13/C12 ratio is NOT unique to burning FFs.("just as the combustion, DECAY, or RESPIRATION of (or by) biomass will add more C12 than C13 to the atmosphere" So he tacitly agrees that the CAGW "unique FF fingerprint" meme is false. He argues that the biosphere cannot be the source of the increased CO2 in the atmos b/c "PHOTOSYSTHESIS WILL TAKE OUT MORE C12 THAN C13 (his bold) by exactly the same amount per tonne of biomass generated"" "While that is true, Curtis's argument fails in his next statement:"Given that the total amount of biomass in the world is stable...". That is a false assumption, similar to the false CAGW assumption that climate is stable except for human interference. Curtis erroneously concludes that 'pseudo-critics' have no coherently worked out counter proposal that could attribute C13/C12 ratio changes to natural changes. This is manifestly false, as I have pointed out to you previously." "I imagine your confirmation bias &/or cognitive dissonance reflex reactions probably wiped them from your memory, but I'll repeat them since it appears yubedude & others are following our exchanges. bit ly/OyWzLj & bit ly/PuDQl Perfectly plausible physical mechanisms to show that natural sources can be significant contributors to the increases in atmos CO2." -
Andrew Skolnick at 04:18 AM on 30 July 2012Mann Fights Back Against Denialist Abuse
I agree with Brandon that "it is inexcusable to compare anyone to a child molester." It's even more inexcusable when the accuser is someone whose teaching career ended after he was arrested and stood trial for sending dozens of obscene messages to a 16-y-o girl, as reported in Brendan Demille's recent HuffPost article, "Affidavits in Michael Mann Libel Suit Reveal Astonishing Facts About Tim Ball Associate John O'Sullivan." http://www.huffingtonpost.com/brendan-demelle/affidavits-in-michael-man_b_1711581.html -
Andrew Skolnick at 04:05 AM on 30 July 2012Mann Fights Back Against Denialist Abuse
I wish what CBDunkerson opined would be a slam-dunkerson fact. Rules regarding the admission of scientific evidence are not so reassuring -- in the United States it is left up to the trial judge to decide what is credible and admissible scientific evidence. (I have to wonder whether judges would allow their legal decisions and competence to be officially judged by a panel of appointed climatologists!) Many judges in the U.S. recognize the inadequacy of the court system for decidng matters of scientific debate. Yet, they are often compelled to reach a decision of fact, based on the persuasive powers of hired-gun scientific witnesses. Clearly, courts are not the place to weigh scientific evidence. Rules of evidence in law courts differ greatly from rules of evidence in the court of science. The first major investigative news article of my career was about the science fraud Dr. William McBride. McBride was the Australian physician made famous by being the first to report limb malformations occurring in babies born to women taking Thalidomide. That brought him fame and fortune, which he used to set up a foundation and go around the world testifying in civil suits against all kinds of drugs -- including drugs like Bendectin that are NOT linked to any increase in birth defects risk. In fact, the removal of this anti-nausea drug due to the cost of fighting almost 2000 bogus law suits enabled by the dubious testimony of "experts" like McBride, resulted in many birth defects caused by uncontrolled maternal nausea during pregnancy! I wrote about this medical and legal travesty in the Journal of the American Medical Association in 1990 ("Key Witness Against Morning Sickness Drug Faces Scientific Fraud Charges" http://jama.jamanetwork.com/article.aspx?articleid=380996). I reported how McBride was facing 15 charges of scientific fraud for publishing made-up data -- some of which he hurriedly made up to include in testimony in a U.S. court. McBride was found guilty 3 years later and struck off the medical registry. What shocked me the most was not his fraud, but that the U.S. Justice Department was not interested in pursuing perjury charges against him despite the compelling evidence he had knowingly provided false testimony and made up data in at least one U.S.court case. There appears to be little or no risk for scientists willing to lie under oath about scientific fact or opinion -- at least not in the United States. -
Daniel J. Andrews at 03:21 AM on 30 July 2012Peter Hadfield takes on the MWP
Oops. I can check Bill Ruddiman's sources on that last item. -
Daniel J. Andrews at 03:19 AM on 30 July 2012Peter Hadfield takes on the MWP
One of the "frustrating" things about this site is that it highlights how quickly my knowledge falls out of date despite my efforts to stay semi-current. Sigh. I can see why denialists harp on a 14 year old hockey stick--it is a lot of work trying to stay current. So once again, thank you to SS and Peter. Time to hit the journals again. Any chance you can do a post or two on some of those ideas highlighted by John in the comments? Intriguing ideas. -
JohnMashey at 03:13 AM on 30 July 2012Mann Fights Back Against Denialist Abuse
re: #31 Yes. #27 ended with suggestions to get people to form opinions. I've interacted with Cozen O'Connor before, studied Roger's book and then had a 2-hour breakfast with him last year. Hence, from fairly direct experience, I heartily concur with Andrew's opinions in #31. However, the blogosphere has a lot of Dunning-Kruger-afflictees who have strong opinions on these affairs, as usual without knowing anything. -
Andrew Skolnick at 02:47 AM on 30 July 2012Mann Fights Back Against Denialist Abuse
Roger McConchie and John B. Williams have a few things in common. For one, McConchie is at the very top of libel law practice in Canada and Williams is at the top here in the United States. Neither one of them would likely "bluff" in PUBLIC. When a good lawyer bluffs, it's done privately. You don't rise to the top of your legal field by inviting a major news organization to humiliate you by calling your bluff and showing everyone you've got nothing but an empty hand. When a lawyer of Mr. Williams stature releases a public statement about an threatened law suit, he's NOT bluffing. If he did, he would not be at the top of libel law practice in the U.S. for long. Mr. McConchie was NOT bluffing when he demanded a retraction and apology from Tim Ball. When Mr. Williams told the press that he's not bluffing, only a fool would doubt him. -
Andrew Skolnick at 02:31 AM on 30 July 2012Mann Fights Back Against Denialist Abuse
BTW, the question as to who is a public figure as pertaining to libel law is not always clear. Generally speaking, all elected officials and people running for public office are. Movie stars and other celebrities usually are (with certain possible restrictions involving invasion of privacy ie. reporting medications and health records, etc.) And parties involved in any "news event," such as crime victims and criminal suspects. They are at least temporarily "public figures." (A person who served time for robbing a candy store 30 years ago when he was 21 years old is NOT a public figure based on that long-ago event.) In addition, people who "thrust themselves into the public limelight" -- those who willingly become a public figure by participating in matters of public concern are public figures. So certainly a scientist like Prof. Mann, who is involved in such a vitally important public debate, would be considered a public figure by any US court judge. To win a suit against his defamers, he would need to prove they knowingly lied or acted with reckless disregard as to the falseness of their accusation that Dr. Mann had committed fraud when he published his "hockey-stick deceptions." -
Pete Dunkelberg at 02:27 AM on 30 July 2012Peter Hadfield takes on the MWP
Thanks, Lanfear. -
Andrew Skolnick at 02:01 AM on 30 July 2012Mann Fights Back Against Denialist Abuse
Anyone who knows anything about U.S. libel law would know to be skeptical about Sceptical Wombat's statement that being a "public figure," Prof. Mann would have to prove Steyn and the National Review "knew" what they published about him was false. Not true. In 1964, the US Supreme Court decision in NY Times vs. Sullivan established the current law regarding "public figures." To win a libel suit in US courts, a public figure like Prof. Mann is required to prove the defendant published or broadcast the defamatory speech with "malice" -- which means either knowing that the speech was false or acting with "reckless disregard as to whether the speech was true or false." That's obviously a MUCH lower bar to clear than proving the party deliberately lied -- which usually requires "smoking gun" evidence (ie. email between the defendants bragging how they got away with a real big whopper.) Simply showing that the reporter made NO effort to verify the defamatory statement and gave the defamed person no chance to respond, is often enough to allow a public figure to win a libel suit. In this case, Prof. Mann should have no trouble clearing the public figure hurdle. -
Tristan at 01:32 AM on 30 July 2012Monckton Misrepresents Reality (Part 3)
Monckton tries his hands at some anti-Muller math. -
Lanfear at 01:21 AM on 30 July 2012Peter Hadfield takes on the MWP
Pete@5 You mean something like this? There seems to be one separately for politicians too (US only). -
Tristan at 01:08 AM on 30 July 2012Medieval Warm Period was warmer
Will we see a discussion of Ljungqvist, F.C., Krusic, P.J., Brattstrom, G. and Sundqvist, H.S. 2012. Northern Hemisphere temperature patterns in the last 12 centuries. Climate of the Past 8: 227-249. At some point? -
Pete Dunkelberg at 00:48 AM on 30 July 2012Peter Hadfield takes on the MWP
This video shows so many deniers it makes me wonder if there is a list of significant public deniers anywhere. How many are there, between 20 and 30? -
shoyemore at 00:29 AM on 30 July 2012Peter Hadfield takes on the MWP
Another small "nit" that might have been mentioned, but possibly was too complicated to explain If the earth heated up very quickly in the MWP (not due to CO2) then that says something about the earth's climate sensitivity to the forcing agent, whatever it was. If it was the sun, it suggests that as the sun becomes more active, coupled with the anthropogenic CO2, then the earth's climate will heat up even faster than it is doing now. Not a propsect Lord Monckton and his minions want to deal with, it seems. PS Well played, Peter Hadfield. Thank God someone has the patience to hunt down those "adjusted" charts. I know I would not. -
mercpl at 23:07 PM on 29 July 2012Peter Hadfield takes on the MWP
Bill, With reference to your comment about Muller's op-Ed piece, i wonder if that is the major announcement that has caused the WUWT site to as suspended publication. Maybe Anthony Watts has changed his mind too. -
Rob Painting at 20:33 PM on 29 July 20122012 SkS Weekly Digest #29
Tom, see: Major influence of tropical volcanic eruptions on the stratospheric aerosol layer during the last decade - Vernier (2011) -
Tom Curtis at 19:36 PM on 29 July 20122012 SkS Weekly Digest #29
Tristan @9, GHG are not the anthropogenic forcings. Over time, aerosols have increased albedo, and changed the properties of clouds which have also affected the global energy balance. Likewise, changes in land use (LUC) have changed the surface albedo, also affecting the energy balance. Importantly, these additional effects are cooling effects and combined, are quite large compared to the GHG forcing, currently almost halving the positive forcing from GHG. They following is Figure 1 C from Skeie et al, 2011 - a recent attempt to quantify all anthropogenic forcings:
Please note the dashed red line, ie, the net effect of anthropogenic forcings.
There are two primary natural forcings, solar and volcanic aerosol emissions. These are shown in the following graph by the IPCC as brown (solar) and dark blue (volcanic):
Unfortunately the figure does not carry through to 2010. In the intervening period, however, solar irradiance has declined. I am uncertain about the volcanic aerosol forcing, but it cannot be very large due to the absence of recent large volcanoes near the equator.
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Tom Curtis at 18:59 PM on 29 July 2012Of Averages and Anomalies - Part 1A. A Primer on how to measure surface temperature change
heb0 @13, actual temperature series from weather stations that are close together geographically are highly correlated (see fig 3 from Hansen and Lebedeff in the main article). They may, however, differ greatly in the absolute value of their measurements. Thus, for example, if you have two weather stations close together, but one on the top of a mountain while the other is near the base, their temperature anomalies from day to day are likely to be very similar, even though the difference in altitude will cause one to consistently record temperatures significantly lower than the other. Indeed, the weather station on top of the mountain may consistently record temperatures much lower relative to the one at the base, than the day to day differences in temperature at both stations. The strong regional correlation, and hence near approximation of the anomalies of nearby stations, is, I believe what makes the average of the anomalies superior to the anomaly of the averages. It is certainly what is violated in Greg Houses example @12. It would be interesting if you were to check this by imposing strong regional correlation on your model, instead of allowing them, as you currently do, to fluctuate at random with respect to each other. -
Doug Hutcheson at 18:58 PM on 29 July 2012Climate Change Cluedo: Anthropogenic CO2
Thanks for this post, Tom. I have linked to it in an amusing debate over at Aussies Living Simply (ALS) (my pseudonym there is 'owlbrudder'). -
Tristan at 18:47 PM on 29 July 20122012 SkS Weekly Digest #29
A humble request for what I'd find to be a useful page, having spent a lot of time in the skeptosphere. What is the observed contribution of GHGs to warming from the 1850-1890 (which I dub 'then') period till now? The page would need The size of the anomaly due to TSI for then vs now The size of the anomaly due to AOD for then vs now And an explanation of: GHG anomaly = total anomaly - AOD anomaly - TSI anomaly And why we're fairly sure that those 3 factors make up almost all the observable temperature differences. It would really put the low sensitivity claims to the sword. It'd make it pretty hard to argue for an ECS of 1.2C if we had a clear link explaining that we've already experienced around that much warming due to GHGs. -
JohnMashey at 17:44 PM on 29 July 2012Peter Hadfield takes on the MWP
Great video, only one real not and one minor one. 1) Wegman Report. Everybody agreed non-centered PCA was not right, but it was also shown (by Wahl&Amman) that it made no significant difference. There was no new good statistics in the Wegman Report, which reran McIntyre's code, and the only way to get his effects was: a) Use unrealistically high persistence parameters b) Do a 1:100 cherry-pick of the most positive hockey-stick looking charts. See Deep Climate's Replication and due diligence, Wegman style. After (falsely) criticizing Mann for never providing code, Wegman then told untruths to Rep Henry Waxman, promising to release the code (never done), as soon as it got through US Navy release procedures. The Navy had nothing to do with it. Anyway, the Wegman Report shows little evidence of statistical expertise. 2) As a minor nit, this shows CO2 over last 2000 years, from Law Dome. While I would never ascribe all the temperature jiggles to CO2, one might notice where the low and high points are compared to the temperature reconstructions. In Plows, Plagues and Petroleum (and earlier papers), Bill Ruddiman proposed several hypotheses: a) Even pre-industrial era, human land-use changes (cutting down trees, rice farming~methane, etc) kept Earth warmer than one would expect from past interglacials. I.e., without humans, CO2 in 1000AD would have been lower. b) CO2 jiggles over last 2000 years have at least in part been caused by human plagues, which caused reforestration, which drew down CO2. The biggest, sharpest dip (1535-1600) seems to have been caused by the single biggest plague in history, the 50M person die-off in the Americas, post-Columbus. c) While controversial ~2005, more scientists have gotten involved and evidence has been piling up in support of these hypotheses. In effect, it means that since agriculture started, humans mostly nullified the start of the long, slow descent to ~180ppm CO2 one would normally expect. Hence, we actually did contribute to the MWP, perhaps and the LIA. The latter is ironic: Europeans gave America smallpox, etc, but got the LIA in return. -
heb0 at 16:33 PM on 29 July 2012Of Averages and Anomalies - Part 1A. A Primer on how to measure surface temperature change
First, thanks for the post. I've found it immensely helpful. I read it when it was first posted and have now found my way back to it to refresh myself. I have one problem, however. I understand the advantages of the 'average of anomalies' method for problems with variations in average temperature between locations, but I'm missing how it is less sensitive to dropped stations than is finding the anomaly of the averages. To test this, I generate an array of 500 average temperatures that vary between 15 and 30 degC, then generate an array of 500 temperatures that are allowed to vary randomly from each station average (within certain bounds). I then create arrays with certain "stations" removed (I've played around with the number, but I started out dropping 20 stations), and then compare all the values: real, average of anomalies, and anomaly of averages. It turns out that neither method is consistently closer to the real value and, in fact, upon 500 iterations of the code, it seems each is the better estimate about 50% of the time. Is this actually the case, or is there some physical explanation for the advantage of finding the 'average of anomalies' when accounting for dropped stations that wouldn't be reflected in my randomly-generated values? -
bill4344 at 16:12 PM on 29 July 2012Peter Hadfield takes on the MWP
Another great vid from Potholer. So, who's been fiddling with the charts, then? Between this and Muller's 'call me a Converted Skeptic' NYT OpEd this is turning into quite the memorable day! -
jyyh at 15:55 PM on 29 July 2012Climate Change Cluedo: Anthropogenic CO2
Hmmph..."12C preference" -
jyyh at 15:53 PM on 29 July 2012Climate Change Cluedo: Anthropogenic CO2
This is going towards of topic...delete if necessary. In the case of CO2, the explanation of 12preference in plants in #42, would mean that the central C in O=C=O rotates horizontally along the long axis of the molecule while the slight excess of negative charge would be located perpendicular to it, making the O=13C=O look a bit fatter than O=12C=O. I'm pretty sure there are better explanations about this within physical chemistry, but I'm not that advanced in that discipline. -
jyyh at 15:28 PM on 29 July 2012Climate Change Cluedo: Anthropogenic CO2
Oops. Of course the change of rate in weathering should be different to 12C and 13C to explain that. It's quite astonishing the binding sites of enzymes in plants can be so selective they may differentiate between atoms of different nuclear charge distribution (the amount of neutrons and their locations). I'd presume the distribution of charge in the nucleus gets mediated to the exact configuration of molecular orbitals and this is sensed by the appropriate coordinated bonds within the photosynthetic machinery. If one wants to go by with the simple model of atoms based on positive-negative charge, one might think that the distribution of the nuclear charge in 13C gets polarised more to the one side of the nucleus so the electrons on that side would be on thighter orbits than usual. -
jyyh at 15:06 PM on 29 July 2012Climate Change Cluedo: Anthropogenic CO2
oh, I think I found out one item missing on the list. The weathering of rocks. I would suspect there hasn't been a change of rate so large in that, and one that would have started when industrial revolution started, that would explain the changed 13/12C ratio. For the sake of completeness this might be included to the list. -
Rob Honeycutt at 14:14 PM on 29 July 2012Climate Change Cluedo: Anthropogenic CO2
Thanks a ton, Tom, for taking the time for such a detailed response. We'll see if he endeavors to respond. -
DSL at 13:11 PM on 29 July 2012The BEST Summary
Muller officially comes out in the NYT today -- with predictions: "What about the future? As carbon dioxide emissions increase, the temperature should continue to rise. I expect the rate of warming to proceed at a steady pace, about one and a half degrees over land in the next 50 years, less if the oceans are included. But if China continues its rapid economic growth (it has averaged 10 percent per year over the last 20 years) and its vast use of coal (it typically adds one new gigawatt per month), then that same warming could take place in less than 20 years." -
Tom Curtis at 12:40 PM on 29 July 2012Climate Change Cluedo: Anthropogenic CO2
Correction: As originally published, section (2) reads in part:"The increase in CO2 concentration over the long term (1850-2005) almost exactly correlates (corr.: 0.981; R^2: 0.962) with cumulative anthropogenic emissions from all sources including Land Use Change (LUC). The close correlation has continued in recent times, with a correlation of 0.977 when compared to the Mauna Loa record (r^2: 0.955). "
Immediately after posting, this will be amended to read as follows:"The increase in CO2 concentration over the long term (1850-2005) almost exactly correlates (corr.: 0.997; R^2: 0.993) with cumulative anthropogenic emissions from all sources including Land Use Change (LUC). The close correlation has continued in recent times, with a correlation of 0.9995 when compared to the Mauna Loa record (r^2: 0.999). "
(Emphasis added in both quotes to highlight the amended values.) The figures initially published show the correlation between CO2 concentration and annual emissions, not cumulative emissions as stated. The corrected figures are for cumulative emissions. -
Chris G at 12:00 PM on 29 July 2012Unprecedented Greenland Ice Sheet Surface Melt
I had the same thoughts as several: Misleading implication of a 150-year cycle resulting from averaging a non-uniform distribution. (Which I had guessed, but not confirmed; thanks Physicist-retired.) Handing skeptics an out on silver platter, etc. I also thought "will be worrisome" was an odd turn of phrase choice. The state of arctic ice isn't worrisome already? In the context of an accelerating ice mass loss, a strong warming trend globally, and polar amplification, I might have used 'expected'. I can't see why one more symptom on a terminal patient would change a state from not 'worrisome' to 'worrisome'. It somewhat appears to me that Dr. Koenig was caught unprepared at an interview, and of course, the skeptics will give more credence to her casual reply than to the actual distribution of events in the data. -
Daniel J. Andrews at 11:26 AM on 29 July 2012Mann Fights Back Against Denialist Abuse
Thanks John. It is always hard to know where to start when learning a new subject that you have no familiarity with. I just found Dr. Mann's facebook page. Already I'm finding it a good resource as he links to new material and articles on climate change that are on sites I either don't frequent often or haven't even heard of. -
Tom Curtis at 09:22 AM on 29 July 2012Climate Change Cluedo: Anthropogenic CO2
Rob Honeycutt @37, firstly, and fairly obviously, the strong correlation between CO2 increases and cumulative human emissions (2), the mass balance (3), the change in the C14/C12 ration (4), the fact that Oxygen levels have declined by less than would be required to explain combustion of fossil fuels (6), and the known record of changes in biomass (9) are all strong evidence against the claim that the CO2 increase is from changes in biomass. More specifically, however, just as the combustion, decay, or respiration of (or by) biomass) will add more C12 than C13 to the atmosphere relative to the existing proportion, so photosynthesis will take out more C12 than C13 by exactly the same amount per tonne of biomass generated. Given that the total amount of biomass in the world is stable, the biosphere can have no net effect on C13/C12 ratios except due to a small deletion of C12 relative to C14 due to biomass lost from circulation by fossilization. Consequently, if the person you are debating wants seriously to argue that the biosphere is the source of the changes in CO2 concentration, they are compelled (if they are consistent) to argue that the biosphere is rapidly shrinking. How rapidly is shown by the fact that the biosphere contains approximately 1,000 billion tonnes of Carbon. (I apologize for referencing wikipedia on this point. Unfortunately searching google scholar simply returned page after page studies into biomass as fuel or as carbon sequestration.) One part per million by volume (PPMV) of CO2 in the atmosphere has a mass of 2.13 tonnes of carbon. That means an increase in CO2 concentration from 280 to 390 ppmv represents 234.3 billion tonnes of Carbon, or over 20% of the world's total biomass. That may seem like to large a decrease to be contemplated, but as it happens, humans have caused the destruction of biomass to the extent of cumulative emissions around 165 billion tonnes of Carbon (17% of the world's total biomass) since 1850 (Houghton 2008, extended to 2011 by persistence). The margin of error is certainly large enough that the 20% could come from human activities alone. Of course, the 20% estimate is letting your debate opponent of lightly. It is known that increases in atmospheric CO2 only represent 57% of total human emissions. Consequently, allowing for the extent of emissions not retained by the atmosphere your opponent would need to claim that over 400 billion tonnes of biomass had been lost. What is worse, in order to account for known human emissions and the known increase in the CO2 content of the atmosphere, to claim the increase is primarily from changes in the biosphere, he would need to claim an even larger fraction of emitted CO2 was not retained in the atmosphere. Just to assume 50/50 responsibility, they would need to claim the airborn fraction was just 28% of all emissions, requiring more than 500 billion tonnes emissions from biomass (on top of the human caused emissions). I think we would have noticed. Of course, such a large net combustion of biomass is also going to require a larger net source of oxygen to account for the limited drop on O2 concentrations. I would say that I cannot wait to see what possible sources would be suggested, but I know better. Pseudo-critics of any scientific theory to not feel it incumbent on themselves to flesh out a coherent alternative proposal. They think it is sufficient to say that biomass has the same C13/C12 ratio as fossil fuels (approx true) and think that that is a devastating criticism even though no coherently worked out counter proposal that implies natural changes in biomass is remotely plausible given the sum of the evidence. -
Papy at 09:20 AM on 29 July 2012Unprecedented Greenland Ice Sheet Surface Melt
I find three points troublesome about this article : 1 - The Lora Koenig's 150 years periodicity allegation, as notified before, so waiting for enlightenments. 2 - The SkS headline in which, as explained in the Joe Romm's article and on Carbonbrief : "the description of 'unprecedented' needs to be qualified - on the latest satellite measurements it's certainly the case, but longer-term records suggest this kind of melt may have happened before." So shouldnt it be : "Satellites see unprecedented Greenland ice sheet surface melt" just like the NASA press release, or "Record Greenland ice sheet surface melt" to put it in a geological era context ? 3 - The missing perspective of this event, however begun by the Gavin Schmidt's comment : "The NASA results are clearly unprecedented in the satellite record (and this is obviously what was being referred to), and come at the tail end of a strong increasing trend in summer surface melt area (as seen in data from the Steffen and Tedesco groups)." Perhaps a graph, presenting maximum ice sheet surface melt extent and its trend like in Mernild et al. 2011, with this new 2012 value plotted, could be usefull ?
Just in order to explain us the diverse hypotheses :
- "whether this year's melting is a one off or the start of a trend".
- or even if it could be both : the consequences of an extreme weather pattern (noise) on a continued multi-decadal upwards surface melting (trend).
Moderator Response: TC: Ask and you shall receive (some times):
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SEAN O at 09:17 AM on 29 July 2012Unprecedented Greenland Ice Sheet Surface Melt
Neven #14' I think that Twemoran nailed it at your place: "Undoubtedly accurate, but there are other ways of expressing how unusual the event is. How about "Only once since Columbus's discovery of America" or "Only twice since the signing of the Magna Charta" Probably cherry picked, but relating historic events to the data might make an effective headline. The thing I drew from the chart was that averaging events that occur in clusters can be misleading. The most recent cluster occurred in the Viking Age with a long dry period following that." I agree with his point that relating the melt event to a well known historical event help the less enumerate among us. -
oneiota at 08:28 AM on 29 July 2012Unprecedented Greenland Ice Sheet Surface Melt
I have to agree with Neven @ 14. I first caught wind of this on Peter Sinclair's site. How could JPL say in the headline "unprecedented" and then in the body of the artcle say that the last event was in 1889 and part of a cycle of 150 years? Sloppy and naive I thought. It gives the rabble something more to froth at the mouth about. I went looking for the Alley paper without success so it is good to see it referenced above. -
Neven at 08:03 AM on 29 July 2012Unprecedented Greenland Ice Sheet Surface Melt
Unfortunately, that 'averaging' was made by a Goddard glaciologist, not a climate skeptic. No 150-year melt cycle exists in the Greenland ice core record, and implying that this melt is 'right on time' is highly misleading. Thanks a lot for this, Physicist-retired. I didn't give it much thought, as I figured it was entirely irrelevant to the event itself, but now that I have thought about it, I find it amazing that Koenig has said this and even more amazing that the people over at NASA put this quote in. They handed the fake skeptics everything they needed to mislead and obfuscate on a silver platter. Wow. Just wow. -
tmac57 at 07:20 AM on 29 July 2012Unprecedented Greenland Ice Sheet Surface Melt
What I would want to know is what is the probability of Greenland's surface melting to this degree in a 10,000 year time frame,given that the climate sensitivity = 3°C,and applied to our current understanding of the historic levels of Co2. (I'm not sure that I phrased that correctly) -
MA Rodger at 06:23 AM on 29 July 2012Unprecedented Greenland Ice Sheet Surface Melt
And you've read the press releases here but have you seen the film by ASCAT - "Greenland Melts July 4-13" Its the sequence of ASCAT daily images during the melt event which had ended by the time the image (18 July) in the post above was taken. An astute commenter at Neven's spotted it & animated it. -
Physicist-retired at 06:08 AM on 29 July 2012Unprecedented Greenland Ice Sheet Surface Melt
Thanks for that link, Sean. It's good to know that Gavin and Joe are already on this. Rob, No harm, no foul. I've done the same thing myself - more than once. And while I've been reading SkS regularly for some time now, I haven't commented here before. -
MA Rodger at 06:06 AM on 29 July 2012Unprecedented Greenland Ice Sheet Surface Melt
When I first saw the 600+ gap prior to the 1889 event on the Alley & Anandakrishnan 1995 graph, my initial thoughts on this claiming of a 150 year average was that it was wrong to use the 10,000 average. But I've revised that view. The 1,000 average has been running at 250 years which isn't that big a difference from 150 and there have been big gaps similar in size to the 600+ one in previous millennia. And with this recent 2012 event, hasn't the running 1,000 year average risen to 200? So it wasn't very exact to claim 150 years. Indeed it was sloppy using that 10,000 year average. But to call it flat wrong? I don't think so. -
SEAN O at 05:27 AM on 29 July 2012Unprecedented Greenland Ice Sheet Surface Melt
Gavin Schmidt as quoted by Joe Romm on : Climate Progress The NASA results are clearly unprecedented in the satellite record (and this is obviously what was being referred to), and come at the tail end of a strong increasing trend in summer surface melt area (as seen in data from the Steffen and Tedesco groups). However, we know Greenland was warmer than today at many intervals in the past – the Early Holocene (from isotopes and borehole temperatures), the last interglacial, the Pliocene etc. so there is no claim that this is something that has never happened in the history of the planet. Furthermore, the ‘every 150 years’ quote is very strange. The data on Summit melt layers – (discussed in the paper you reference http://www.igsoc.org/annals.old/21/igs_annals_vol21_year1995_pg64-70.pdf ) and more easily visible here: http://www.gisp2.sr.unh.edu/DATA/alley1.html – indicates that the [1889] event was actually the only event in the last ~700 years, and there have only been 6 in the last 2000 years (4 of which were associated with the Medieval Climate Anomaly btw 750 and 1200AD). Hardly a frequently recurring ‘cycle’! The all-Holocene average that Koenig is referring to includes the warmer Early Holocene where orbital variability was driving warmer northern high latitude summers — and which is not relevant to the expected frequency in today’s climate.Moderator Response: TC: Link corrected, quoted links made active. For those who are interested, the first quoted link is to the paper (Alley and Anandakrishnan, 1995) that discusses previous melt links. The second is to a colourized version of fig 1 from that paper, which is shown by Daniel Baeley @2 above, and has the caption:"Figure 1. Melt against age (upper panel) and July insolation against age (lower panel) for the GISP2 site. Years containing melt features are shown by thin dotted lines. The heavier textured line is the 100-a running mean of melt frequency (number of melt features per 100 years), and the heavy black line is the 1000-a running mean. The lower panel shows deviation of July insolation from modern values in calories/cm2/day, from Berger (1978; 1979); positive values indicate more insolation than today. Data from: Alley, R.B. and S. Anandakrishnan. Variations in melt-layer frequency in the GISP2 ice core: implications for Holocene summer temperatures in central Greenland. Annals of Glaciology 21, 64-70 (1995)"
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Rob Honeycutt at 04:02 AM on 29 July 2012Unprecedented Greenland Ice Sheet Surface Melt
My apologies, Physicist-retired. I misinterpreted your comment. I spend too much time debating on other forums where people claim to be scientists and will reject basic radiative physics. -
Physicist-retired at 03:57 AM on 29 July 2012Unprecedented Greenland Ice Sheet Surface Melt
Thanks, Daniel. -
Daniel Bailey at 03:31 AM on 29 July 2012Unprecedented Greenland Ice Sheet Surface Melt
You make a valid point. It would probably deserve a more in-depth treatment than just a comment on a related post. I'll send an email off to Dr. Box and to some of the other glaciologists for their thoughts and insights. -
Rob Honeycutt at 03:27 AM on 29 July 2012Climate Change Cluedo: Anthropogenic CO2
Hey guys, I have someone on Peter Sinclair's channel who won't come and comment here but I wanted to post his comments related to Tom's point #5 and see what the responses are. He states... "We were talking about C13/C12 ratio. It's the same for burning FF as it is for decaying plant matter, as they are both from organic/photosynthesis sources." He says that the C13/C12 ratio can not be attributed solely to FF burning. Now, I know what my response would be but I wanted to see what others have to say. -
Physicist-retired at 03:22 AM on 29 July 2012Unprecedented Greenland Ice Sheet Surface Melt
Rob, Perhaps I haven't made my point clear. I am aware of Arctic sea ice trends, the 'sticky' jet stream, the numerous warm high pressure ridges that formed over Greenland beginning in May (culminating in early July), and other atypical phenomena that led to this startling GIS melt event. I've also read Box (2012). To anyone following this closely, the July melt should not be too much of a surprise. But even scientific reporting on the melt infers that it could be part of a 'natural 150-year cycle', which does not actually seem to be accurate. My comments are not intended to request clarification on the drivers behind this melt, but rather to inspire SkS authors to explain that Koenig's comment is inaccurate and misleading. I've seen no one do that to date, and I believe it's important. Perhaps I'm wrong. -
Rob Honeycutt at 03:06 AM on 29 July 2012Unprecedented Greenland Ice Sheet Surface Melt
Physicist-retired... I think you also have to put the current ice melt into context with the many other lines of evidence. We have been seeing the Arctic sea ice disappearing far more rapidly than the model projection. We are looking at seeing seasonally ice free conditions within the next decade, or maybe sooner. That is clearly a condition that has not been seen for at least a million years and potentially much longer. We certainly have not been seeing a seasonally ice free Arctic every 150 years. And that's just for starters. You can't just look at the data in isolation. -
shoyemore at 01:25 AM on 29 July 2012Muller Misinformation #1: confusing Mike's trick with hide the decline
Tom #197, Thanks. You made my day, possibly my week. :)
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