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Comments 79401 to 79450:

79401. Hyperactive Hydrologist at 20:15 PM on 15 July 2011
       Why Wasn't The Hottest Decade Hotter?
       Dikran - thanks for your response. Could we see a the trend in global temperatures continuing if India decides to start building coal power stations at an increasing rate? 1.2billion people in India, we can't expect them to go without electricity forever. Indian Coal Rush
79402. Rob Painting at 19:12 PM on 15 July 2011
       Why Wasn't The Hottest Decade Hotter?
       Barry - "The point of your post is that the globe has not warmed as we had expected, and we've come up with a new analysis to answer that. We've changed our narrative and we need to be careful in expressing it properly." Barry, you seem to imply some sort of flip-flop by SkS. That's not the case, there's a significant difference between "skeptic" claims of global cooling (wrong) and slower rate of warming (right). I don't expect the future rate of warming will be steady, nor did I expect the past decade to be, so there's no narrative to change. Heck, even the ocean heat content data and sea level rise, show a slowdown during this period. However, when you step back and look at the long-term trend, global warming just keeps on trucking. Like the teeth of a mangled hand saw blade, the future will see global warming in fits and starts. Indeed if the past equator-to-pole, and surface-to-deep-ocean, temperature gradients are any indication of the future, then we should expect periods where there is very little surface warming - when the deep ocean heats up. But also intervals where there is abrupt warming. The abrupt warming intervals are what concerns me.
79403. Dikran Marsupial at 18:51 PM on 15 July 2011
       Why Wasn't The Hottest Decade Hotter?
       Hyperactive Hydrologist IIRC the most recent IPCC WG1 report attributes most of the warming in the first half of the 20th century to solar forcing. The similarity in the rates is probably just a coincidence; the warming we see is a result of changes in multiple forcings, both positive and negative, so there are many ways to get the same trend.
79404. Hyperactive Hydrologist at 18:46 PM on 15 July 2011
       Why Wasn't The Hottest Decade Hotter?
       Apologies if this is off topic: From just eyeballing figure 1 the increase in temperature between 1910 and 1940 seems to be similar to current rate of warming. Is this just due to the early on set of global warming from emission during the industrial revolution? Or is there some natural forcing during that period as well?
79405. Rob Painting at 18:45 PM on 15 July 2011
       Why Wasn't The Hottest Decade Hotter?
       Cynicus - " This question keeps nagging in the back of my head and I would like to have this clear: "Why wasn't the hottest decade hotter?", you imply: without Eastern Asian aerosol emissions it would have been even warmer?" I don't imply, I state at much. That's a consequence of the statistical modelling of radiative forcing used by Kaufmann (2011). The two climate modelling studies cited in the post show that Asian reflective aerosol emissions are more potent than either European or North American emissions - historically the worst polluters. Dr James Hansen also seems to be of the opinion that the sun-shield provided by sulfates is much stronger than commonly suggested in scientific circles. If he and Kaufmann are right, and only time and further research will tell, then there's a lot of warming in the pipeline.
79406. ranyl at 18:08 PM on 15 July 2011
       Why Wasn't The Hottest Decade Hotter?
       "Or, is the Kaufmann aerosol paper trying to explain a slowdown in warming that doesn't even exist?" This is true but considering things carefully compared to all others barometers of excessive energy in the system the actual rise in air temperature has been modest at least. As well as the direct reflection of SO2 there are also the very large brown clouds over Asia which heat the atmosphere and trap energy in the system but shade the surface bringing in another artificial cooling of surface temperatures. China is about to cut its SO2 emissions as the air is getting hard to breath there now. http://business.globaltimes.cn/china-economy/2011-03/632936.html What is the climate sensitivity to GHG again?????! Also it has recently been shown that due to the effects of nitrogen ferttilisation, despite being a biodiversity diaster has been cooling the planet due to ozone interactions and enhancement of the apparent CO2 fertilization effect (excess nitrogen in the eco-system has fertilized the forests making the land CO2 sink seem greater than it actual is).http://www.nine-esf.org/ENA Now all these cooling influences are short term and the cuases for need to cease for health reasons alone, so that means that warming if GHG theory is correct is about to truly start to get going. This is concerning considering how much it is going already. Add in the La Nina prevelance in the 2000's and the solar low and well that 2010 was the hottest year on record seems beyond understanding unless the CS is a lot higher than thought, or in line with paleoclimatic suggestion. 400ppm peak anyone!!!??? That gives a carbon budget of 4 years to prepare for what is likely to be the most rapid change in the earth's climate so far.
79407. villabolo at 17:47 PM on 15 July 2011
       Why Wasn't The Hottest Decade Hotter?
       Robert Gates @ #20: "If you listen to the AGW skeptics, they are preparing for a Little Ice Age to begin any day now and to last for decades." What I've seen at WUWT and Steve Goddard's sites is that they, and their posters, are predicting everything and anything. I challenged Goddard to give his prediction for the state of the Arctic ice cap in 2020. His answer was that the Arctic ice cap would grow, shrink or stay the same. I taunted him on the predictive power of 'skeptic' science. Their Orwellian view amounts to "The earth is cooling, it's cooling! Isn't it good that it's (naturally) warming (we'll get to pet the dinosaurs)." Since they have set the 'goal posts' everywhere, they cannot go wrong. In any case, we have a thermal lag of 1F(?) within 30 years and a highly reduced Arctic ice cap. What's the calculated rise in temps for an ice free Arctic, 5-6F? That, in turn, creates a feedback loop for Siberian Methane production due to increased melt and methanogen metabolism. As for aerosols, China might be giving us a large chunk of it but, if we were to have a global depression, all nations' aerosols would be lowered. I don't think that GW will be leveled by the 'three sisters'.
79408. MarkR at 17:41 PM on 15 July 2011
       Why Wasn't The Hottest Decade Hotter?
       I was surprised by the publication of this article, but in a way it sort of makes sense - it appears warming was less than it would otherwise have been without China's aerosols. 800 million Hiroshima's worth of heat entered the upper oceans since 1998, trillions of tons of ice have melted and a few hundred million Hiros have gone into the deep ocean. So we were definitely not in radiative balance either. We still warmed, just not by as much. The thing with aerosols is that you have to keep increasing them to keep pace with CO2. Seems unlikely that China will, but perhaps other industrialising countries will help prop up our sunshade.
79409. cynicus at 17:36 PM on 15 July 2011
       Why Wasn't The Hottest Decade Hotter?
       @4 Riccardo, Thanks. I think I understand better now. I had the impression that this article (and Kaufmann) was about decadal trends but instead it is primarily about a few years (i.e. <10 years variability)? Rob Painting: This question keeps nagging in the back of my head and I would like to have this clear: "Why wasn't the hottest decade hotter?", you imply: without Eastern Asian aerosol emissions it would have been even warmer?
79410. Tom Curtis at 17:14 PM on 15 July 2011
       Why Wasn't The Hottest Decade Hotter?
       Sorry, forgot to mention La Nina in my point (6) above.
79411. Tom Curtis at 17:12 PM on 15 July 2011
       Why Wasn't The Hottest Decade Hotter?
       Barry @19, I don't know about "our" narrative, but my narrative has been: 1) You don't measure trends just by measuring maxima; 2) You don't measure global temperatures by excluding the poles from the globe; 3) You don't determine long term trends by looking at less than a decades data; 4) Taking 1-3 into account, there has been ongoing global warming in the period 2001-1010 at a rate similar to the preceding two decades; 5) There may have been a slight reduction in the rate of warming in the last three years due primarily to an unusually for the 2000's cold year in 2008, although an unusually warm year for any other decade of the instrumental record; 6) That slight reduction in the rate of warming was probably due to increased aerosols from China, and to an exceptionally (second lowest in 100 years) low solar minimum. I see nothing in this paper to change that narrative. On the contrary, all I can see is a plausible explanation of some noise in the trend, which tends to confirm (6). Further, I notice that a significant defect of the paper is that it does not use a temperature index including polar values, and does not relate the explanation to the very unusual Arctic warmth.
79412. Tom Curtis at 17:00 PM on 15 July 2011
       2nd law of thermodynamics contradicts greenhouse theory
       alistair @1075: You noted that the radiative equilibrium is achieved at 5 km altitude. This is, of course, a feature of our current atmosphere because it contains gases that emit and absorb in the IR portion of the spectrum, ie, in the wavelengths of peak emissions for a black body at 255 degrees K. In the non-greenhouse case, the case with no IR absorbing or emitting gases, radiative equilibrium necessarily is achieved at the surface. That is because, with no IR radiating gases, all radiation to space from Earth must come from the surface. As all radiation comes from the surface with no green house gases, it necessarily follows that the altitude of radiative equilibrium is at the surface. It follows that the surface temperature will be the temperature that results in radiative equilibrium, ie, 255 degrees K. With no GHG, and ignoring the effect of ozone, the average temperature at 5 km will be 206 degrees K (255 - 5 * the dry adiabatic lapse rate). Heat would cease being carried from the surface by convection once the atmosphere establishes a thermal profile equal to the dry adiabatic lapse rate. Most importantly, if heat did not stop being carried away by convection, you would be invoking a violation of the first and/or second law of thermodynamics. Specifically, the heat being carried away would not be then radiated to space because there would be no IR radiating gases in the atmosphere. Therefore it would accumulate until equilibrium of heat exchange with the surface was achieved, something accomplished when the dry adiabatic lapse rate describes the heat profile of the atmosphere. Heating beyond this point would require net heat to flow from the colder to the hotter body (2nd law violation), or else the heat in the atmosphere to be dissipated without flowing back to the surface. As we have established the heat is not radiated to space because of there being no IR radiating gases, the second case requires non-conservation of energy.
79413. alistair at 16:24 PM on 15 July 2011
       2nd law of thermodynamics contradicts greenhouse theory
       Your claim that the greenhouse warming at the Earth's surface is 33K is plain wrong. This is because for an opaque [to IR] atmosphere, the -18°C equilibrium with space is in the upper atmosphere, about 5 km up. The surface temperature is then set by the rise in temperature from the lapse rate, c. 6.5K/km. So, the Earth's surface temperature is c. 33K higher than the upper atmosphere's radiative equilibrium 'temperature'**. If you take out the GHGs, the IR radiation from the Earth's surface is then not absorbed in the atmosphere, so it cools. However, your claim that the earth's surface would fall to -18°C is plain wrong because you still have the lapse rate, a consequence of gravitational potential energy. Because only a small proportion of heat is directly radiated from the Earth's surface, most is convected away and because the IR emissivity of N2/O2 is very low, that heat remains as sensible heat. The real GHG warming of the earth's surface is a bit less than 10K. If you still believe it's 33K then you have to go back to your basic education. **To calculate that you have to do a Hottel analysis. [-snipped-]
79414. R. Gates at 15:41 PM on 15 July 2011
       Why Wasn't The Hottest Decade Hotter?
       This study certainly offers a plausible scenario for the slowing of the rise in global temperatures. An important measurement will be the average temperatures of the decade from 2010-2019. There could be a real mixed bag here. Fro example: How much will the sulfate aerosol emission from China have slowed in the decade? What if we enter into a Dalton or Maunder type minimum with the sun? What if we have a series of La Nina years continuing through the decade? Given this potential "triple whammy" of cooling forces, if somehow 2010-2019 is even hotter as a decade than 2000-2009, this will certainly be quite telling, or even if temperature simply level for the period. If you listen to the AGW skeptics, they are preparing for a Little Ice Age to begin any day now and to last for decades. I think they'll be disappointed, but, considering what it means for continued warming, you almost wish they would be right.
79415. Ari Jokimäki at 15:39 PM on 15 July 2011
       Thinning on top and bulging at the waist: symptoms of an ailing planet
       About two months ago, a paper by Roy & Peltier was published. Their results are very well in line with this new study: "Recent trends in the two primary anomalies in the rotational state of the planet are analyzed in detail, namely those associated with the speed and direction of polar wander and with the non-tidal acceleration of the rate of axial rotation (via the measurement of the changing oblateness of the Earth's shape). It is demonstrated that a significant change in the secular trends in both of these independent parameters became evident subsequent to approximately 1992."
79416. barry1487 at 15:31 PM on 15 July 2011
       Why Wasn't The Hottest Decade Hotter?
       It is interesting, but that was not my point. I don't think what we explore here should be constrained by the skeptic narrative, but the main thrust of this blog is rebutting skeptical views.

       Explaining climate change science & rebutting global warming misinformation

       (Headline on the home page here) All I'm suggesting is a small change to accommodate skeptical readers, and which in any case would be consistent with the science. The point of your post is that the globe has not warmed as we had expected, and we've come up with a new analysis to answer that. We've changed our narrative and we need to be careful in expressing it properly.
79417. guinganbresil at 15:01 PM on 15 July 2011
       Trenberth on Tracking Earth’s energy: A key to climate variability and change
       Ken Lambert #31:

       "The CERES satellite data quoted in the Aug09 paper for 2000-05 were adjusted to an estimated imbalance of 0.9W/sq.m from an absolute value of about +6.4W/sq.m. The latest data shown in Fig 3 above shows an Rt value varying around the 1.0W/sq.m. How is this data 'adjusted' from the absolute value?"

       It looks to me like the CERES product "EBAF" provides only clear-sky fluxes for all regions... Figure 3 should not be interpreted to represent actual net radiation - It doesn't include the effects of clouds...
79418. Rob Honeycutt at 15:01 PM on 15 July 2011
       Monckton at odds with the very scientists he cites
       Camburn @ 12... No, I think Dr Abraham has stated this correctly. There are regions that show warming during the Medieval times, but that warming occurred in different regions and at different times. And some places, like the Tibetan Plateau saw no MWP period at all. You might double check the Vostok ice core for a MWP. I don't see it there. Byrd core? Nope. Not there either. Miller 2010 states that the planet has been on a slow cooling trend globally over the past 6000 years force by a changing tilt in the planet's axis. We have likely warmed the planet to about equal with the Holocene Optimum, which is a reversal of the natural trend. What is unprecedented is that we have reversed this natural global cooling trend over the course of about 1% of the time span of the Holocene.
79419. scaddenp at 14:46 PM on 15 July 2011
       Monckton at odds with the very scientists he cites
       Hmm, worth noting the AR4 comments on HCO. I'd say there was evidence it was warmer then. I don't know the global picture well, but certainly local evidence of higher sea level in NZ and Australia earlier and also evidence of glacial retreat further back in HCO than now. Timing of the HCO particularly hemispherically may be more problematic, but the sealevel proxy is worth noting.
       Response:

       [DB] Thanks for weighing in.  I was referring to Hansen & Sato 2011, which contend current temperatures have equalled those of the HCO.  From P. 19:

       "Augmentation of peak Holocene temperature by even 1°C would be sufficient to trigger powerful amplifying polar feedbacks, leading to a planet at least as warm as in the Eemian and Holsteinian periods, making ice sheet disintegration and large sea level rise inevitable.

       Empirical evidence supporting these assertions abounds. Global temperature increased 0.5°C in the past three decades (Hansen et al., 2010) to a level comparable to the prior Holocene maximum, or a few tenths of a degree higher."

       The biggest issue by far with Camburn's Tale is the implied because-it-was-warm-before-therefore-this-current-warming-is-nothing-to-be-worried-about.  Of course, that approach only makes sense if one knows little about climate science other than what one has been spoon-fed on denialist blogs.  The underlying physical processes responsible for the previous warmings brought up as a diversionary tactic (the MWP, the RWP and the HCO) are pretty well understood to be different than that faced by mankind today (anthropogenically-sourced CO2). 

       Hence my refering to Camburn "prosecuting a narrative".
       

79420. Camburn at 14:21 PM on 15 July 2011
       Monckton at odds with the very scientists he cites
       DB: I have to get to sleep. Time permitting, tomorrow I will post links for the RWP.
       Response:

       [DB] Then post them here: Ljungqvist broke the hockey stick

       The RWP is off-topic on this thread.

       Sleep well.

79421. TJ Brookes at 14:15 PM on 15 July 2011
       Great Barrier Reef Part 3: Acidification, Warming, and Past Coral Survival
       Maybe somebody needs to drop this report on Julia Gillard and Tony Abbotts desks and ask is this what you are aiming for..... I am in constant outrage at the lack of leadership...
79422. Camburn at 14:05 PM on 15 July 2011
       Monckton at odds with the very scientists he cites
       Ok....I thought this was common knowledge: Warmer in China during the Holocene Optimum China warmer during Holocene Optimum Alley 2000 Greenland Ice core data confirms warmth. North Greenland beaches ice free during the Holocene Optimum. Greenland North Beach ice free during holocene optimum Data from Antarctica showing the early Holocene Optimum in the ice cores: Antarctic Ice cores showing Holocene historical temperatures
       Response:

       [DB]  It is common knowledge:

       1. The Alley core data dates to no more recently than 1905.  Recent temperatures at the drill site are unprecedented.
       2. The Vostok core data (and the other Antarctica core data) use 1950 as present.
       3. The China Holocene paper looks to verify the existence of the Holocene optimum via pollen data, nothing more.

       You are throwing "stuff" at walls in the hope that some may stick (you grasp at straws).  Regardless, this amorphous discussion serves no purpose on this thread.  If you wish to prosecute this narrative further, do it here:

       Most of the last 10,000 years were warmer

       Grasp away there.

79423. scaddenp at 14:04 PM on 15 July 2011
       It's Pacific Decadal Oscillation
       Fair enough about index - the "SO" about ENSO was an index and there is the MEI for expressing ENSO strength. However, ENSO is now reasonably well understood as a coupled ocean/atmosphere phenomena where the physical system can be expressed if not predicted very well. PDO remains just an index. It's an indicator of what is happening the oceans, it is not yet linked to any causitive physical system. And that index may be no more than another expression of the ENSO physical system. The interest with temperatures is not to link them to any index, but to link them to underlying physical system. This would happen if it was discovered there was an underlying ocean phenomena beyond ENSO.
79424. Camburn at 13:25 PM on 15 July 2011
       Monckton at odds with the very scientists he cites
       "Other studies reinforce the view that when considered either by hemisphere or globally, the temperatures we are experiencing now are truly unprecedented". Mr. Abraham: I would suggest that you change the wording of this sentence. We all know that the Holocene Optimum had temperatures warmer than present temperatures. And indications from sea level proxy data, pollin data proxy etc strongly indicate that the Roman Warm Period was warmer than present temperatures. As far as the MWP, areas had substained temperatures as warm or warmer than present temperatures.
       Response:

       [DB] "We all know that the Holocene Optimum had temperatures warmer than present temperatures."

       Umm, nope.  Got a source for that?  Anyway, that's off-topic.

       "the Roman Warm Period was warmer than present temperatures"

       Again wrong.  And off-topic again.

       "As far as the MWP, areas had substained temperatures as warm or warmer than present temperatures."

       Still wrong.  And still no cites, so now you're just trolling.

       Look, if you're not going to even try to adhere to the standards expected of one adding comments on a climate science blog forum (Rule #1, always back up assertions with links to reputable sources), then don't expect your comments to survive moderation. 

       Be advised.

79425. Rob Painting at 13:03 PM on 15 July 2011
       Why Wasn't The Hottest Decade Hotter?
       Barry -"it looks like we've finally admitted what the skeptics have been saying, and have leapt upon the first reason to explain it that we can. We've dropped one argument in favour of another that contradicts the first." Barry, "skeptics" have been predicting global cooling for decades now, but the Earth keeps on warming - pretty much like we expect it to. Rather than constrain ourselves to "skeptic" narratives isn't it useful or at least interesting to examine why there is short-term variability?
79426. barry1487 at 12:56 PM on 15 July 2011
       Why Wasn't The Hottest Decade Hotter?
       I've posted in the PDO thread. I think we're missing something there.
79427. Bob Lacatena at 12:51 PM on 15 July 2011
       Why Wasn't The Hottest Decade Hotter?
       From the OP:

       As East Asia begins to install smokestack scrubbers to reduce sulphate pollution...

       Does anyone have any idea what the time frame will be on this? My nightmare scenario would be ten or fifteen years of masked global warming, followed by a sudden, nightmarish takeoff that stuns the skeptics and the public and the politicians... but by then it's much, much too late.
79428. barry1487 at 12:34 PM on 15 July 2011
       It's Pacific Decadal Oscillation
       Revisiting this topic after discussion in a recent thread: I think it's clear that the PDO has a negligible impact on centennial trends (if at all), but the skeptical focus is on decadal trends, and the argument is that the global temperature trend of the last 30 years or so is partly a result of the upswing (to about 1998). A question i've had in mind is about the difference between ENSO and PDO, where the former is linked to short-term fluctuations in the global temperature record, but the PDO is not. the language most often used is something like 'PDO shifts heat around within the system, but doesn't influence global temps.' I do not understand why one ocean/atmosphere system with fluctuating temperature indices should impact global temps (ENSO) and another shouldn't. In the other thread, I asked about this and was directed here with the comment, "PDO is basically an index whereas ENSO is a physical system." PDO and ENSOS are both expressed as indices - temperature indices. I don't see how one is a 'physical system' and one isn't. Nor does it matter what causes PDO or ENSO for the purposes of my enquiry. If PDO has a decadal influence on global temps, then it can be said that the thirty year global temp trend to 1998 may partly be a result of the PDO warm phase. Solar variability and cosmic rays show no trend for this period, but if PDO can be linked to decadal fluctuations in global temps, then the notion that natural factors have had a negligible effect on the trend for this period is undermined. Consequently, the trend rate for the last 30-40 years is only partly to do with CO2. I think skepticism has largely moved on from claiming the PDO is responsible for global warming on centennial scales, but I don't think we yet have a satisfactory response to argument about PDO effect on shorter time-scales.
79429. Andy Skuce at 12:09 PM on 15 July 2011
       Thinning on top and bulging at the waist: symptoms of an ailing planet
       Yvan Dutil You are correct that change day length is rather less of a tidy story than the changes in oblateness measured by SLR and GRACE. Day length is affected not only by mass distribution changes in the atmosphere, oceans, cryosphere and lithosphere but also by changes in angular momentum in the Earth's outer, liquid core. Dynamical effects in the outer core produce measurable changes in day length with a cycle of 65-80 years. You may find this article to be of interest.
79430. Eric (skeptic) at 12:03 PM on 15 July 2011
       Why Wasn't The Hottest Decade Hotter?
       barry, thanks for the correction http://cses.washington.edu/cig/pnwc/compensopdo.shtml I don't want to discuss that further here, it was only supposed to be an example.
79431. scaddenp at 12:00 PM on 15 July 2011
       Why Wasn't The Hottest Decade Hotter?
       The proper thread would be Its the PDO. PDO is basically an index whereas ENSO is a physical system. There is some evidence that PDO may be long-lived integrator of the ENSO cycle. See the linked article.
79432. Andy Skuce at 11:49 AM on 15 July 2011
       Thinning on top and bulging at the waist: symptoms of an ailing planet
       WSteven: Yes, thanks, you are right, centrifugal force is a fictional force, like the Coriolis force, but I figured that the people who already knew why the equator bulged wouldn't be confused by the term and those who didn't know wouldn't have heard of centripetal forces. There's often a trade-off between precision and clarity when it comes to terminology.
79433. barry1487 at 11:42 AM on 15 July 2011
       Why Wasn't The Hottest Decade Hotter?
       That begs another a question I have in my mind from previous comments at this blog and others. I've read in various places that the PDO moves heat around, and doesn't by itself contribute to fluctuations in global temperature. This is different from ENSO, where it is explained that this ocean atmosphere system does have that influence. I've never understood why these systems should be distinct in this fashion. If PDO does provide multi-decadal influence on global temperature (as ENSO does on shorter time scales), then there's meat to the argument that the PDO is signal is apparent in the instrumental record, and that the high warming rate of the last 30 years may partly stem from that. This doesn't affect the centennial trend much, but it would have an impact on the last 30 years or so, which trend has been argued to be a result almost entirely of CO2, natural factors (solar, cosmic rays) showing little trend. Dunno if this is the right thread for discussing that...
79434. Rob Honeycutt at 11:40 AM on 15 July 2011
       Monckton at odds with the very scientists he cites
       AT @6... When filtering out all the duplicate references there are 297 papers listed as part of the CO2science MWP project. I've just started collecting and reading the papers. What's immediately and clearly evident is the 1) the MWP is heterogeneous both spacially and temporally, and 2) there are far fewer southern hemisphere proxies. When you start digging in you start realizing what a large and complex project it must be to put together a global proxy record for the past 2000 years.
79435. bothersome at 11:33 AM on 15 July 2011
       Monckton at odds with the very scientists he cites
       Beware of those who claim they get relativity. Beware of those who haven't gone through the grinder that is the formal study and examination of a subject to high level, which is a necessary but not sufficient condition to begin to say 'I think I get it'. Thank you John Abraham for all your hard work.
79436. Eric (skeptic) at 11:30 AM on 15 July 2011
       Why Wasn't The Hottest Decade Hotter?
       Another explanation is natural: 80's and 90's was AGW + natural, 00's was AGW - natural. A few natural factors fit the mold, the best one is PDO which was positive in the 80's and 90's which culminated in the 1998 El Nino which has yet not been repeated.
79437. barry1487 at 11:23 AM on 15 July 2011
       Why Wasn't The Hottest Decade Hotter?
       Even something simple like:

       ...the rate of global warming in the last decade or appears to have slowed...

79438. barry1487 at 11:22 AM on 15 July 2011
       Why Wasn't The Hottest Decade Hotter?
       The confusion, though, is understandable. The mainstream has consistently said that a decade is too short to establish a meaningful (statistically significant) trend, so when the article heads up with;

       the rate of global warming in the last decade or so has slowed

       it looks like we've finally admitted what the skeptics have been saying, and have leapt upon the first reason to explain it that we can. We've dropped one argument in favour of another that contradicts the first. Yes, Kaufmann is talking about short-term variability: my issue is with the first sentence in the above article. Talking about a change in 'rate' implies trend analysis, and ten-year global temperature trends are statistically insignificant. I think the article should be amended, so that skeptics who don't read the comments are not confused.
79439. Icarus at 10:17 AM on 15 July 2011
       Why Wasn't The Hottest Decade Hotter?
       Thanks Rob - I should have read the article better!
79440. Rob Painting at 10:07 AM on 15 July 2011
       Why Wasn't The Hottest Decade Hotter?
       Dana @ 1 - love the cartoon!
79441. Yvan Dutil at 10:06 AM on 15 July 2011
       Why Wasn't The Hottest Decade Hotter?
       Icarus, I got exactly the same reaction as you and I even send the Tamino work to Kaufmann, who I have met in a meeting a few months ago. I still waiting for the answer.
79442. Rob Painting at 10:03 AM on 15 July 2011
       Why Wasn't The Hottest Decade Hotter?
       Icarus - as stated by Riccardo @ 4, Kaufmann looks at short-term variability. Long-term all the temperature datasets show warming, that's what the physics of the increased Greenhouse Effect dictate, but why does it vary on shorter timescales? What's going on there? The details aren't yet clear, but citing 'natural variability' explains nothing. "So is there good evidence that there really was an increase in negative forcing from industrial aerosols in this period?" See figures 2 & 3.
79443. WSteven at 09:55 AM on 15 July 2011
       Thinning on top and bulging at the waist: symptoms of an ailing planet
       Good article on the mass re-distribution occurring due to the melting ice-sheets. One minor nitpick, being a science blog wouldn't it be better to avoid using fictional forces in discussing such as the earth's bulge at the equator? I suppose it's easier to say centrifugal as it's "common knowledge" and all, but I spend a lot of time trying to explain to kids that it's not a real force. Again, a minor nitpick. Thanks for posting this, Andy.
79444. Doug Mackie at 09:52 AM on 15 July 2011
       Great Barrier Reef Part 3: Acidification, Warming, and Past Coral Survival
       @DLB: It seems scarcely credible that anyone reading could have missed the point that the rate of change is of concern. I do hope you pay more careful attention to the OA not OK series so as to remedy your admitted ignorance of ocean acidification.
79445. Humanracesurvival at 09:05 AM on 15 July 2011
       Trenberth on Tracking Earth’s energy: A key to climate variability and change
       From above study: However, all current global climate–carbon cycle models ignore a potentially important soil biological heating term that could change this situation radically.
79446. Humanracesurvival at 09:00 AM on 15 July 2011
       Trenberth on Tracking Earth’s energy: A key to climate variability and change
       I just saw this related study.. Soil carbon and climate change: from the Jenkinson effect to the compost-bomb instability First generation climate–carbon cycle models suggest that climate change will suppress carbon accumulation in soils, and could even lead to a net loss of global soil carbon over the next century. These model results are qualitatively consistent with soil carbon projections published by Jenkinson almost two decades ago. More recently there has been a suggestion that the release of heat associated with soil decomposition, which is neglected in the vast majority of large-scale models, may be critically important under certain circumstances. Models with and without the extra self-heating from microbial respiration have been shown to yield significantly different results. The present paper presents a mathematical analysis of a tipping point or runaway feedback that can arise when the heat from microbial respiration is generated more rapidly than it can escape from the soil to the atmosphere. This ‘compost-bomb instability’ is most likely to occur in drying organic soils with high porosity covered by an insulating lichen or moss layer. However, the instability is also found to be strongly dependent on the rate of global warming. This paper derives the conditions required to trigger the compost-bomb instability, and discusses the relevance of these to the concept of dangerous rates of climate change. On the basis of simple numerical experiments, rates of long-term warming equivalent to 10°C per century could be sufficient to trigger compost-bomb instability in drying organic soils.
79447. Icarus at 08:52 AM on 15 July 2011
       Why Wasn't The Hottest Decade Hotter?
       I don't really understand the Kaufmann issue. Different temperature series give quite different trends from 1998 to 2008 - If you go by GISTEMP then there was no decrease in the warming rate at all, and if you go by UAH the decrease was minimal. If you adjust all series for variations in solar irradiance, volcanic aerosols and ENSO, as Tamino has done here, then it's not apparent to me that any of them show any decrease in warming in this period that needs to be explained with industrial aerosols: So is there good evidence that there really was an increase in negative forcing from industrial aerosols in this period? If so, that suggests to me that the anthropogenic greenhouse warming trend which underlies the natural variability must be even greater than Tamino's analysis indicates (if it's offset by a negative forcing that his analysis doesn't take into account). Or, is the Kaufmann aerosol paper trying to explain a slowdown in warming that doesn't even exist? Isn't 10 years too short a period to really be confident about a trend anyway, regardless of what series you use?
79448. Humanracesurvival at 08:51 AM on 15 July 2011
       Trenberth on Tracking Earth’s energy: A key to climate variability and change
       Ok, but we have now 4% more water vapor around - increase of precipitation, especially the upper 10% of heavy downpours, shifting patterns and a more acidic environment beside other factors, then 30years ago. So the energy budget of the Pedoshere is going up, a lot more energy input vise which faster erodes and weathers. And here we have sinks and we know that warmer temperature is increasing Decomposition and Denitrification. And we know that during the PETM distinct layers (suboxic/hypoxia) formed in the ocean/land mass acting like a blocking layer of energy transport. So i wonder if these "growing" sinks can not be accountable for the "missing energy". Because i don't know how the models work and how exactly the energy budgets are quantified i have to ask.
79449. Riccardo at 08:26 AM on 15 July 2011
       Why Wasn't The Hottest Decade Hotter?
       cynicus you need to distinguish between long term trend (Hansen) and short term variability (Kaufmann). And also understand that Jones didn't say there has been no warming.
79450. Eric the Red at 08:19 AM on 15 July 2011
       Why Wasn't The Hottest Decade Hotter?
       I think the question was always there. The lack of warming has been apparent for quite some time, but many people have tried to claim that is wasn't. Kaufman offers a plausible explanation, which seems to be echoed by Hansen. We will have to wait for other research to confirm this/

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