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Comments 42401 to 42450:

42401. tcflood at 12:03 PM on 3 September 2013
       Greenhouse Effect Basics: Warm Earth, Cold Atmosphere
       

       MThompson @88;

       How black body-like the earth's emission is depends on the details of the specific piece of surface, but on the average I think the consensis is that it is about 90% BB-like. So, yes, the earth's IR emission in the region around 700 cm-1 is absorbed efficiently by the CO2. The key point here, though, is that in the troposphere that excited CO2* (* means excited state) undergoes about 10^10 collisions each second and the excitation energy is transferred at about that rate to all the gases in the immediate vacinity, thus, contributiong to the thermal pool. The rate of spontaneous emission in the mid IR range tends to correspond to lifetimes of the excited state on the order of milliseconds, which is way too long for the specific originally excited CO2* (lifetime of a few hundred picoseconds) to have any probability of just emitting the photon directly back out.  Thus, the low equilibrium percentage of CO2* in the atmosphere can essentially be thought of as coming entirely from the Boltzmann thermal equilibrium and this is the population from which re-emission of the IR occurs.

       It sounds like your population of from 6-15% of CO2* may have been calculated assuming the ground state is singly degenerate. I think the ground state and excited state are both doubly degenerate for the bending mode so the percentages may be half of that. I'm not sure on this point. Maybe someone else can comment.

42402. K.a.r.S.t.e.N at 09:32 AM on 3 September 2013
       Study offers clues on 20th century global warming wobbles
       

       Interesting paper with a different approach to a long-standing problem. Well worth a read, though some aspects are certainly debatable. One thing in the paper that I tend to disagree with is the authors notion that aerosol effects are likely less over oceans. Given the low albedo, even a small increase in aerosol the loading matters (more than over land). To their credit, the SH oceans are indeed less affected, although this might have changed in the last decade. All effects together, I don't think they overestimate the global temperature trends due to aerosols with their land only results.

42403. MThompson at 08:32 AM on 3 September 2013
       Greenhouse Effect Basics: Warm Earth, Cold Atmosphere
       

       tcflood @87

       Thank you for the clear explanation of how the rotational modes broaden the primary transitions. I am still trying to understand how the bending vibrational mode of CO₂ gets populated. I see from the Maxwell-Boltzman distribution that about 6% to 15% of gas molecules at earth temperatures have enough kinetic energy to excite the CO₂ bending mode. Now my question is: “Do photons from the earth’s blackbody spectrum in the range of 13-18 microns ( 770 to 560 cm^_-1) pump ground-sate CO₂ molecules to the bending mode?”

42404. BillEverett at 04:01 AM on 3 September 2013
       2013 SkS Weekly Digest #35
       

       The bad link was serendipitous for me. I clicked the link in comment 1 and found something I want to follow. Thanks for the link error and resulting comment!

42405. CollinMaessen at 03:56 AM on 3 September 2013
       2013 SkS Weekly Digest #35
       

       Cheers. :)

42406. tcflood at 03:10 AM on 3 September 2013
       Greenhouse Effect Basics: Warm Earth, Cold Atmosphere
       

       MThompson @86,

       At atmospheric temperatures only a few percent of CO2 molecules are in the first vibrationally excited state. All the rest are in the vibrational ground state. Thus, vibrational transitions to higher levels are not involved. The broadness of the bending mode comes from the fact that each vibrational state has a large number of rotational levels populated, and vibrational transitions can be from a lower to a higher rotational level ("R-branch" transitions) or from a higher to a lower rotational level ("P-branch" transitions). The rotational component of the one vibrational transition can broaden the spectral absorption band by hundreds of wavenumbers. These ever more wide-spread transitions, by the way, are why the CO2 absorption band (and water bands, for that matter, never fully "saturate" with increasing levels of water and CO2 in the atmosphere.  

42407. dvaytw at 01:05 AM on 3 September 2013
       It's El Niño
       

       Rob thanks.

       I understand why as a serious scientist you don't want to spend time on crank ideas. That said, I'm debating people in online forums where there are a lot of non-science people, and pseudo-scientists often know their pseudo-science better than do those defending the real science, which means they can actually appear to be winning debates even when wrong - and this can influence people's opinions.

       This is why I make the effort to actually find out what's wrong with Tisdale's "hypothesis" - because a fellow in a debate is using Tisdale's video about ENSO (which specifically targets SkS, incidentally!), and for the scientifically challenged, it can seem convincing.

       
       So based on your response, my next question is this: how do we know that "over time, in a stable climate, they would balance out to zero?" I seems in the information provided above, our measurements only go back to 1980.

42408. John Hartz at 00:20 AM on 3 September 2013
       2013 SkS Weekly Digest #35
       

       Collin Maessen: Link fixed. Thank you for bringing this to our attention. Also, thank you for all that you do.

42409. MA Rodger at 18:02 PM on 2 September 2013
       Study offers clues on 20th century global warming wobbles
       

       The paper's URL.

       The headline numbers for climate-watchers will be the impact of Rs on Global Land Temperatures shown in Fig 6a & also presented in Table 1 as rate of change per century yielding on the back of my envelope - 1900-39 +0.02C, 1940-84 -0.16C, 1985-2010 +0.017C, with this last period starting in the aftermath of the El Chichon eruption.

42410. One Planet Only Forever at 15:13 PM on 2 September 2013
       Global warming...still happening
       

       Daniel,

       There are many people who are looking for any possible excuse to believe that activity they benefit from is not a problem. There is a very sucessful deceptive marketing effort that preys on that desire. It uses any means to delay global action that would actually significantly reduce the burning fossil fuels.

       So my comment remains that using a comment like "the past decade was the warmest" will be successfully abused by the decievers and delayers saying "we need to wait for the next full decade of data before we do anything". If you are not careful about what you try to argue with you can make it easier for someone to "beleive what they prefer to believe", even if you know they have misinterpretted the point you were tryng to make.

       The warming of the earth due to human activity is indeed beyond scientific dispute. It has been for more than a decade. This issue is now political. How something is said matters more than the actual facts in politics. The best way to deal the decievers is to present infromation that is very difficult to "take advantage of". You have to remember that much of the population has "a vested interest in not properly understanding this issue". Much of the population cares more about getting more benefit for themselves than they do about future consequences others will face.

42411. CollinMaessen at 14:16 PM on 2 September 2013
       2013 SkS Weekly Digest #35
       

       I noticed that when my website is referenced that it's pointing to some internal link on SkS that apparently requires a login. For anyone that is interested you can find the referenced blog post here.

42412. MThompson at 14:00 PM on 2 September 2013
       Greenhouse Effect Basics: Warm Earth, Cold Atmosphere
       

       Phil @82

       Daniel @84 

       Thanks for pointing out how the energy distribution factors into this. After reading your comments I did quite a bit of poking around online to refine my understanding. The big CO₂ peaks may overlap some with molecular water, but the CO₂ components seem to span a wavelength range of roughly 13-18 microns. Does this range correspond to higher quantum number states of the bending mode? It seems transitions between asymmetric stretch and bending mode have wavelength of about 9.5 microns.

42413. Daniel Bailey at 12:27 PM on 2 September 2013
       Toward Improved Discussions of Methane & Climate
       

       Northbeacher, rather than continuing on in your variant of your arguments from personal incredulity, note that the OP is written by a climate scientist and repeatedly references the primary literature, so asserting your own personal opinions to the contrary carry little weight here.

       Given the vast differences in amounts being injected back into the carbon cycle, CO2 has a much greater Radiative Forcing than does methane.  And that's the most important consideration, not the Global Warming Potential of the various gases.

       

       FYI, for the Arctic, the OH radical found there is primarily produced in the tropics and then transported poleward (source).

       

       [Source]

42414. Northbeacher at 10:50 AM on 2 September 2013
       Toward Improved Discussions of Methane & Climate
       

       My personal thoughts on this article. Okay, I realize we all go off on excessive tangents on occasion, myself included, and maybe my retort is yet another example of that, but...

       But this article begs that I protest. Because the world is in great peril from global warming. From the feedback loops of global warming. From the ireversible tipping point thresholds of the feedback loops of global warming. From the abrupt "climate change" [sic] that will result...

       Yes, many of the feedback loops are methane related, but there are many more KNOWN major feedback loops which this article ignores. Add to the known feedback loops the new UNKNOWN feedback loops, which are constantly being discovered...

       The planet is in exponentially imminent danger of a failing to support its increasingly overpopulated hoards.

       Dirty energy and its charlatan shills are much too effectively dumbing down voters to continue having their dirty way with destroying the planet.

       So, someone overstates -- debatably, somewhat -- that the planet is collapsing. So what? Why go to such extensive extremes to refute it? Seems voters need some counter-bullshitorama to push them into voting out climate deniers rather than downplaying and lowballing the reality of what we are truly faced with.

       This article brings new meaning to "wrong headed", if not, as previously noted, just plain wrong in at least a couple of aspects, but frankly, many more that I did not (yet?) take the time to expose...

       IBM in the 60's used to have the simple motto of "Think". Consider that in your future endeavors to protect the human habitat from those mindless morons that destroy it in the name of greed. Voters need to wake up, not be lulled into complacency by articles like this. Shame on you...

42415. Jonas at 10:08 AM on 2 September 2013
       The Beginners Guide to Representative Concentration Pathways - Part 3
       

       Thank you for this in depth introduction!

42416. Northbeacher at 10:01 AM on 2 September 2013
       Toward Improved Discussions of Methane & Climate
       

       Substantiating my earlier contention that methane should not be summarily dismissed...

       Methane is 20 times more potent as a greenhouse gas than carbon dioxide. This recent lecture by James Hansen of NASA notes methane regulation has more short-term potential to slow climate change than does carbon regulation.http://www.columbia.edu/~jeh1/2009/Copenhagen_20090311.pdf

       Given that methane is about 25 times stronger as a greenhouse gas per metric ton of emissions than carbon dioxide...
       http://www.nasa.gov/home/hqnews/2008/oct/HQ_08-276_Methane_levels.html

       Methane, with a warming potential 72 times that of carbon dioxide over a 20 year time frame, having a half-life of only 7 years.
       http://www.dailykos.com/story/2013/06/19/1217235/-MIT-Climate-Fast-Solution-to-Climate-Change-Is-On-Your-Plate#

       Pound for pound, the comparative impact of CH4 on climate change is over 20 times greater than CO2 over a 100-year period.
       http://www.epa.gov/climatechange/ghgemissions/gases/ch4.html

       Over 100 years, a ton of methane would heat the globe 23 times more than a ton of carbon dioxide.
       http://oceana.org/en/our-work/climate-energy/climate-change/learn-act/greenhouse-gases

       Methanes Lifetime Global warming potential over CO2
       20-yr 12 times  100-yr 72 times  500-yr 7.6 times
       https://en.wikipedia.org/wiki/Greenhouse_gas#Greenhouse_gases

42417. Northbeacher at 09:07 AM on 2 September 2013
       Toward Improved Discussions of Methane & Climate
       

       Methane is 23 times stronger as a greenhouse gas than Carbon Dioxide in the short run and 72 times stronger in the long run. I have noted variations of that statement hundreds of times by credible scientific sources. This article seems to state something on the order of the opposite?

       For brevity, singling out just one other minor point the article makes on methane, where hydroxyl radicals counter CH4...

       First on the highly ephemeral hydroxyl molecules: they are produced when ultraviolet radiation bombards common gases such as ozone and water vapor. The resultant OH molecules typically have a lifetime of less than one second because they immediately react with various gases (not just methane).

       Secondly, the shrinking ozone hole contributes to producing extra hydroxyl radicals. As the ozone hole recedes -- and an ever thicker greenhouse shield blocks more ultraviolet radiation -- so to does the production of hydroxyl molecules recede.

       Thirdly, as pollution, smog, and brown haze increase, a feedback threshold may eventually be crossed such that the hydroxyl oxidation process goes into sharp decline, ceasing to be a significant offsetting factor.

       I could go on and on, as their are other sources of the methane bomb unmentioned in the article, but this is just a "comment" and my brief point has been made.

       So, in abbreviated conclusion, I am perplexed... Is it even remotely possible the author is downplaying the methane gorilla in the greenhouse for some reason?

       Moderator Response:

       [DB] "Is it even remotely possible the author is downplaying the methane gorilla in the greenhouse for some reason?"

       Speculation to motive contravenes the Comments Policy in this venue.  Please focus on the evidence.

42418. Daniel Bailey at 05:01 AM on 2 September 2013
       CO2 lags temperature
       

       Tzedakis et al 2012 found that the threshold for the current interglacial / glacial transition was about 240 ppm CO2, so that is in-line with other research.

42419. tcflood at 04:46 AM on 2 September 2013
       CO2 lags temperature
       

       Daniel,

       Thanks for your response. An especially interesting feature of their modeling results is that if [CO2} is kept constant at 220 ppm, the model still produces the 100 ky ice age cycle. If [CO2] is kept constant 260 ppm, the ice ages disappear. If [CO2} is kept constant at 160 ppm, the ice age frequency is much higher and interglacials are much colder.

       These models point to non-linear coupling of numerous variables that is indeed complex.  From my point of view, it is exciting to finaly see a quantitative treatment that actually does reproduce the periodicity, shape, and intensity of the ice age/interglacial cycles. Now perhaps they can begin to really nail down the explicit quantitative role of [CO2] in all of this and finally lay the "lag" BS to rest. 

42420. tcflood at 04:27 AM on 2 September 2013
       Greenhouse Effect Basics: Warm Earth, Cold Atmosphere
       

       KR @80

       Can you give a reference for your stated radiative lifetimes? I thought spontaneous emission in the mid IR (at the CO2 bending mode) had lifetimes on the order of milliseconds, not microseconds.

42421. Daniel Bailey at 04:18 AM on 2 September 2013
       Global warming...still happening
       

       "some may claim the need to "wait for the next decade of data" before having to admit anything"

       Some still claim the Earth to be flat.  Empirical, observational evidence and physics demonstrate otherwise.

       "a claim could be made that the decadal rolling average has stopped climbing, because it has"

       Circular reasoning bordering on sloganeering.  The ongoing energy imbalance at the Top Of our Atmosphere (TOA) amply demonstrates the utter, physics-less falsehood of this statement.  A claim could be made that sheep's bladders could be employed to prevent earthquakes.  So what?

42422. Daniel Bailey at 04:06 AM on 2 September 2013
       CO2 lags temperature
       

       tcflood, the Nature paper is important in that the modeling efforts are able to successfully simulate the various ice age cycles, including the 100,000 year cycle, by successfully identifying and accounting for the various knock-on feedbacks.  These feedbacks include albedo, CO2 levels, ice sheet configuration (including elevation), air- and ocean-circulation changes.

       The researchers obtained their results from a comprehensive computer model, where they combined an ice-sheet simulation with an existing climate model, which enabled them to calculate the glaciation of the northern hemisphere for the last 400,000 years. The model not only takes the astronomical parameter values, ground topography and the physical flow properties of glacial ice into account but also especially the climate and feedback effects.

       Using the model, the researchers were also able to explain why ice ages always begin slowly and end relatively quickly. The ice-age ice masses accumulate over tens of thousands of years and recede within the space of a few thousand years. Now we know why: it is not only the surface temperature and precipitation that determine whether an ice sheet grows or shrinks. Due to the aforementioned feedback effects, its fate also depends on its size.

       The paper confirms, via modeling, that the aforementioned effects (combined with Milankovitch orbital forcings) can account for the various iterations of the ice age glacial / interglacial cycles.

       Above quotes are from the Phys.org article linked below.
       
       http://phys.org/news/2013-08-ice-ages-feedback.html

       The Shakun et al 2012 paper showed that warming was indeed triggered by the Milankovitch cycles, and that small amount of orbital cycle-caused warming eventually triggered the CO2 release, which caused most of the glacial-interglacial warming. So while CO2 did lag behind a small initial temperature change (which mostly occurred in the Southern Hemisphere), it led and was the primary driver behind most of the glacial-interglacial warming.

       According to the Shakun data, approximately 7% of the overall glacial-interglacial global temperature increase occurred before the CO2 rise, whereas 93% of the global warming followed the CO2 increase.

       http://www.skepticalscience.com/skakun-co2-temp-lag.html

42423. tcflood at 03:27 AM on 2 September 2013
       CO2 lags temperature
       

       RE: 397-399

       Let me try again:

       Here is a paper.

       What is the SkS take on it?

42424. One Planet Only Forever at 03:21 AM on 2 September 2013
       Global warming...still happening
       

       Daniel @ 16.

       I would caution against the presentation of decadal averages without also showing the trend line of rolling averages of a decade of data. A new decadal average can be claculated for each new month of data. However, some may claim the need to "wait for the next decade of data" before having to admit anything. Also, a claim could be made that the decadal rolling average has stopped climbing, because it has. However, averages of larger sets of data that would include the recurrance of signifcant variable factors such as El Nino continue to climb.

       The numbers and statistics game can be played in many ways. Even the 30 year average shows fluctuations resulting from the many variable and random factors that affect Global Average Surface Temperature.

       What is important, and challenging, is the presentation of information in a way that will make it harder for people to "believe what they prefer to believe".

42425. Andy Skuce at 02:02 AM on 2 September 2013
       The Beginners Guide to Representative Concentration Pathways - Part 3
       

       I don't think it is fair to say that CCS is not working, at least at a technical level, the few pilot projects that are running seem to be working OK. The problems with CCS are economic, scalability and regulatory. 

       The economic problem could be solved with a hefty carbon tax, which is easier said than done, of course. 

       The scalability problem is much more problematic, since the mass of CO2 that has to be stored is about three times the mass of the fossil fuels that produced it. Establishing a new global industry much bigger than the current oil, gas and coal industries in a matter of decades is not feasible. Note that in all of the RCPs, the absolute amounts of fossil fuels consumed increases by 2100. The scalability problem is not so much a question of the size of the potential reservoirs, but our ability to build the infrastructure to put the CO2 there.  

       The regulatory problem is a major stumbling block in my opinion. Geological CCS has all of the problems of unconventional gas development and more and, if it is to be a climate-relevant solution, it will have to be implemented in sedimentary basins everywhere. The potential hazards of CCS are real and include leakage, earthquakes, industrialization of the landscape and groundwater contamination. The regulatory and public acceptance problems will make CCS more expensive, slower to implement and more limited in scope. 

       rustneversleeps and I wrote a long piece on CCS recently that covered some of these points in more detail. 

42426. owenamoe at 00:01 AM on 2 September 2013
       Global warming...still happening
       

       Global warming is produced by an energy imbalance at TOA, an imbalance which is evidenced most clearly in accumulating ocean heat content.  I would suggest that you use the latest NOAA values for OHC (http://www.nodc.noaa.gov/OC5/3M_HEAT_CONTENT/basin_data.html)  which show, through the first quarter of 2013, an unabated rise in heat accumulation on earth (as oceans absorb ~93% of that imbalance).  The atmospheric temperatures, due to the far, far lower heat capacity of the atmosphere relative to the oceans, and driven by the current set of ocean-atmosphere heat transfer mechanisms (ENSO, PDO, AMO, thermohaline circulation, etc), provide the least reliable assessment of an energy imbalance at TOA is derived from atmospheric temperatures.  A ton of statistics on a poor indicator is not particularly helpful.

42427. michael sweet at 19:41 PM on 1 September 2013
       The Beginners Guide to Representative Concentration Pathways - Part 3
       

       Perhaps I am behind the times, but my understanding is that none of the CCS schemes is working.  Does anyone have a link to an up to date summary of the status of CCS?  If CCS does not yet work, it will be difficult to implement in a timely fashion.

       On the other hand, wind and solar continue their amazing drop in cost.  Wind is already the cheapest new source of energy and will soon be cheapest even compared to coal plants that are paid for.  Solar is economic for home installation in areas with expensive electricity and will soon be economic everywhere.  I have started to look at how to install solar at my home in Florida even though Florida has no incentives.

42428. Rob Painting at 18:15 PM on 1 September 2013
       It's El Niño
       

       dvaytw - it's not strictly true that El Nino and La Nina simply move heat around. But over time, in a stable climate, they would balance out to zero. The only reason the climate system is gaining energy in the long-term is because the increased Greenhouse Effect is trapping more heat in the surface ocean.

       That's why global temperature, and therefore subsurface ocean temperature, tracks atmospheric CO2 so well in the ice core records over the last 800,000 years.

       I don't consider it a worthwhile exercise spending time on crank ideas from Bob Tisdale.   

42429. Rob Painting at 17:50 PM on 1 September 2013
       CO2 lags temperature
       

       tcflood - the abstract is here: Abe-Ouchi et al (2013) - Insolation-driven 100,000-year glacial cycles and hysteresis of ice-sheet volume.

       Sounds interesting. Note that it relates to the 100,000-year cycle - as stated in the abstract:

       "Carbon dioxide is involved, but is not determinative, in the evolution of the 100,000-year glacial cycles."

       Your comment omits this crucial bit of information.

42430. tcflood at 16:08 PM on 1 September 2013
       CO2 lags temperature
       

       Sorry.  For completeness, the authors on that Nature paper are Ayako Abe-Ouchi, Fuyuki Saito, Kenji Kawamura, Maureen E. Raymo, Jun’ichi Okuno, Kunio Takahashi, and Heinz Blatter.

42431. tcflood at 15:58 PM on 1 September 2013
       CO2 lags temperature
       

       I have always been bothered by the lack of a detailed and convincing explanation for the 100 ky periodicity of the last four ice ages when the periodicity of northern temperate zone insolation intensities from Milankovich cycles (my understanding is that this is the important component of these cycles) is close to 20 ky.  A recent paper in Nature (Vol 500, August 8, 2013, page 190) presents an explicit explanation and also describes how CO2 has a role but is not determinative in ice age/interglacial cycles. What do you people at SkS think about this paper?   

42432. dvaytw at 15:39 PM on 1 September 2013
       It's El Niño
       

       Thanks for the info, Rob, but what do you think of my characterization of the problem with his hypothesis?  I'm trying to sum it up in a way that is hospitable to people like myself without a solid science background.

42433. Dave123 at 11:36 AM on 1 September 2013
       Global warming...still happening
       

       I'm imaging the climastrology reponse to Dan Bailey's repost of the excellent Climate Central graphic-

        

       begin simulation exercise

       'Ya see...we had 4 steps up and a plateau from 1900-1940, so we've had 4 steps up now, so we're due for another plateau!!!  If only climate scientist could count with the fingers on one hand'

       (end simulation exercise).

42434. Andy Skuce at 09:57 AM on 1 September 2013
       The Beginners Guide to Representative Concentration Pathways - Part 3
       

       I tend to agree with chriskoz that the level of CCS envisaged in all but one (RCP8.5) of the pathways seems unrealistically high. Also, the amount of solar/wind/geothermal generation seems very low; this category is the smallest (or nearly so) in all four pathways in Figure 14 above.

       

       This triangular diagram from van Vuuren et al is interesting. In all four pathways, fossil fuels (with or without CCS) make up greater than 50% of energy technologies by 2100, and it is only in the final few decades that the fossil fuel share drops below 62.5% and only in two of the pathways (3PD and 4). Considering that absolute levels of fossil fuel consumption rise in all four cases (Fig 14) and that much of the CCS activity, especially geological storage, will likely be handled by future versions of the big oil companies, the demise of Exxon et al may not be a foregone conclusion.

       I know, these are not forecasts, just projections, but it is surprising that none of the pathways models the kind of energy transition (i.e.,renewables-dominant, with little fossil fuel and CCS) that many green-minded people envisage.

42435. Jonas at 09:47 AM on 1 September 2013
       2013 SkS Weekly News Roundup #35B
       

       Link for second article is missing. Here it is: http://grist.org/climate-energy/carbon-targets-carbon-taxes-and-the-search-for-archimedes-lever

       Moderator Response:

       [JH] Missing link inserted. Thanks for bringing this to our attention. 

42436. jonthed at 07:18 AM on 1 September 2013
       Global warming...still happening
       

       I still don't understand why this argument hasn't already been put to bed. I've seen several news articles and papers in recent months talking about the pause in warming being linked ot the enso cycle, as if this was news? Surely this was patently apparent ever since this chart was first circulated:

       http://skepticalscience.com/graphics.php?g=67

       All trends continue upward, it's just we're still in the la nina and neutral territory of the spectrum.

       It seems obvious to me that the next El Nino is gonna prove decisively what this chart already shows.

42437. Joel_Huberman at 05:33 AM on 1 September 2013
       Global warming...still happening
       

       Thanks, Daniel (#16), for the very nice graph from Climate Central. One from NASA that conveys a similar lesson can be found here. In the NASA graph, small differences can be seen among the four datasets/interpretations. The dataset/interpretation from the Japanese Meteorological Society shows 1998 as the warmest year on record, but the datasets/interpretations from the other three sources show 2005 and 2010 as being slightly warmer. Consistent with the graph from Climate Central, the graph from NASA clearly shows (by simple eyeballing) that, regardless of dataset/interpretation, the decade 2001-2011 was warmer than any preceding decade.

42438. Daniel Bailey at 04:38 AM on 1 September 2013
       Global warming...still happening
       

       Joel, depending on the datasets used, 2005 and/or 2010 each equalled 1998 as the warmest year for the surface temperature record.  However, when viewed as decadal averages, the most recent decade has been the warmest, by far:

       

       Source

42439. empirical_bayes at 03:05 AM on 1 September 2013
       Global warming...still happening
       

       @VeryTallGuy for #2, @Ari Jokimäki for #7,

       I am not familiar in depth with the Santer et al (2011) calculations, but a quick look at their Appendix and their Equation (A1) and runup to that suggests these a pretty ad hoc.  They themselves say, in their paragraph numbered "68":

       While non‐independence of samples is an important
       issue in formal statistical significance testing, it is not a
       serious concern here. This is because our pc(i)′ and pf (i)′
       values are not used as a basis for formal statistical tests.
       Instead, they simply provide useful information on whether
       observed TLT trends are unusually large relative to modelbased
       estimates of unforced trends, or unusually small relative
       to model estimates of externally‐forced trends.

       I can't comment on what they are trying to do here, but it's fair to say this is no conventional kind of statistical significance being calculated.  Worse, statistical "significance" cannot be properly used in the way VeryTallGuy seeks to do so, and as many do.  "Significance" has a specific technical meaning, and I would strongly recommend reviewing that, e.g., at http://en.wikipedia.org/wiki/Statistical_hypothesis_testing#Interpretation See also http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1756718/

       The problems classical significance testing or hypothesis testing has in complicated situations is one of many reasons why modern statistical inference is couched in the Bayesian view. See the text, J. Kruschke, Doing Bayesian Data Analysis for a great introduction. Alternatively, check out http://hypergeometric.wordpress.com/2013/08/22/soon-you-will-be-one-of-us/

42440. Joel_Huberman at 01:42 AM on 1 September 2013
       Global warming...still happening
       

       Thanks to both Ari and the moderator (DB) for the explanation. I hadn't realized that the data shown in the Berkeley Earth summary graph had been corrected in the same way that the red line in Ari's graph had been corrected. The explanatory legend at the Berkeley Earth site didn't make that clear. But it makes sense, because the red line in Ari's graph resembles all four lines in the Berkeley Earth summary graph. I conclude that the uncorrected global temperature in 1998 has not yet been exceeded by any subsequent uncorrected annual average global temperature.

42441. Ari Jokimäki at 01:24 AM on 1 September 2013
       Global warming...still happening
       

       Joel, the caption of the figure in question mentions the data-source for the pink line: "one year running mean averaged from all surface temperature analyses". Further details are available in Rahmstorf et al. paper to which there's a link in the references section.

42442. Joel_Huberman at 00:57 AM on 1 September 2013
       Global warming...still happening
       

       Very nice article, but there's one thing I don't understand. The pink line in the second figure suggests that the uncorrected global temperature in 1998 was higher than for any succeeding year. In contrast, other global temperature measurements, such as the four measurements graphed on the "Berkeley Earth" summary page suggest temperatures higher than 1998 in several of the succeeding years. My guess is that a different global temperature data set was used to generate the pink line, different from the data sets used to create the lines in the Berkeley Earth summary graph (NASA GISS, NOAA/NCDC, Hadley/CRU, and Berkeley Earth). Am I right? In any case, it would always be a good idea to provide the source of any data set used to make graphs.

       Moderator Response:

       [DB] The paragraph immediately following the legend for that graphic fully explains the corrections done:

       As we can see from the graph, surface temperature changes shown in pink sometimes go outside the projections. This is because some factors are not included in IPCC projections. Such factors are solar activity changes and eruptions of volcanoes. Additionally, the variation of El Niño/La Niña is random and therefore it doesn't change in simulations at the same time it does in real life. IPCC projections are combined results from many simulations, so the El Niño/La Niña variations of different simulations tend to cancel out when simulation results are combined. This means that the projections don't actually include El Niño/La Niña variation either. It should be noted that even if surface temperature shown in pink doesn't stay within limits of projections, it does stay within limits of all individual simulations (not shown in the Figure above).

       Once these exogenous and transitory factors are removed, the underlying trend emerges, shown in red.

       The BEST version, using a similar accounting:

       

42443. BillEverett at 23:58 PM on 31 August 2013
       2013 SkS Weekly News Roundup #35B
       

       Several things in the livescience article "Cooler Pacific Ocean May Explain Climate Change Paradox" disturbed me.

       1. The Pacific Ocean (as a whole ocean) is warmer, not cooler. The equatorial surface has been cooler, which is what happens when we have a turnover of warmed surface water going down and cold deep water coming up. "Cooler Pacific Surface" would be more accurate.

       2. What "Climate Change Paradox"? Deniers claiming "global warming has stopped" doesn't create any climate change paradox, let alone a paradox that needs to be explained.

       3. The picture caption "A thermometer in the Earth shows increasing global climate sensitivity" is absurd.

       The actual article isn't so bad, although I wish that a little more clarity had distinguished the difference between the surface and the ocean, making it clear that we can have a cool-warm surface alternation with a cool or cooling ocean or with a warm or warming ocean, and that we currently have the surface alternation with a seriously warming ocean (bad news). The packaging of the story (not likely the fault of the writer) shows a level of scientific understanding that I would expect to see on a denier site.

42444. Dave123 at 21:52 PM on 31 August 2013
       Global warming...still happening
       

       Solomon isn't seeing any recent increase in stratospheric water vapor, and Chapman's contribution spectrogram seems to confirm this.  Over a longer period then we need to look to Dessler (2010) for long term water vapor feedbacks.  You can just bet that some of the denierrati will jump on this to argue that there are no positive feedbacks, that we're limited to forcing from increased CO2 only, ECS is about 1C and thus all is right with the world.

42445. Rob Painting at 19:17 PM on 31 August 2013
       It's El Niño
       

       Actually SkS has been writing about this oscillation for years, a.k.a the Interdecadal Pacific Oscillation (IPO). For the latest discussion see this recent(ish) SkS post: A Looming Climate Shift: Will Ocean Heat Come Back to Haunt us?.

       The oceans are warming due to the increased (enhanced) Greenhouse Effect (this is the upward slope in the 2nd graphic below), but the wind-driven ocean circulation moves back-and-forth between intense and sluggish phases, which results in the 'hiatus' and 'accelerated warming' decades. The net effect is illustrated in the graphics below:

           

          

       SkS will have upcoming posts/rebuttals explaining this in some more detail. You'll see how the observations by Kosaka & Xie (2013) tie in nicely with the wind-driven ocean circulation.

       Good to see Bob is slowly coming around to our way of thinking though. He still has a looooong way to go.

42446. dvaytw at 18:46 PM on 31 August 2013
       It's El Niño
       

       Hey guys: Bob Tisdale’s crowing about the recent studies attributing slowed surface warming to La Nina:

       “Anyone with a little common sense who’s reading the abstract and the hype around the blogosphere and the Meehl et al papers will logically now be asking: if La Niña events can stop global warming, then how much do El Niño events contribute? 50%? The climate science community is actually hurting itself when they fail to answer the obvious questions.

       And what about the Atlantic Multidecadal Oscillation (AMO)? What happens to global surface temperatures when the AMO also peaks and no longer contributes to the warming?

       The climate science community skirts the common-sense questions, so no one takes them seriously."

       http://wattsupwiththat.com/2013/08/28/another-paper-blames-enso-for-the-warming-hiatus/#more-92630

       How’s this for a summary argument against the Tisdalian hypothesis (if it constitutes one):

       Tisdale and his crowd at WUWT seem to think temperature is just a number that just moves up and down somewhat arbitrarily, like a stock price.  They don't conceptualize things properly in terms of heat energy, which can't be created or destroyed.  
       
       ENSO doesn’t generate, absorb or destroy heat. So when Tisdale says La Nina “stops” global warming and El Nino “contributes”, he’s got it totally wrong. Nothing is being stopped – the heat energy is simply being moved around.  That's why we use the term "oscillation".  

       And the proper question to ask Tisdale is simply, Where is the heat coming from?

        

       I'm probably getting it all mucked up, as I have little science background, but I'm trying to put it in easy terms for non-sciencish people like myself.

       Also, what do you think of this graphic from Hotwhopper:

       ENSO without AGW:
       

       ENSO without AGW:
       

42447. CBlargh at 15:54 PM on 31 August 2013
       CO2 was higher in the late Ordovician
       

       @Tom:

       Wait!  They may not be unrelated!  I just read a paper suggesting roots increase weathering.

       <a href = "http://www.pnas.org/content/98/8/4290.full.pdf">Falkowski and Rosenthal</a>

       
       If the late Ordovician was the first time land rhizomes evolved, it would suggest to me it could have caused a pulse of calcium which pulled down atmospheric carbon in the sea, not necessarily in freshwater bogs through the land plants themselves.

42448. Daniel Bailey at 12:06 PM on 31 August 2013
       Greenhouse Effect Basics: Warm Earth, Cold Atmosphere
       

       Molecular visualizations of CO2 from the GIF's (from Timothy Chase's website):

       Ground State Mode

       

        

       Pure Symmetric Stretching Mode

       The pure symmetric stretching mode v1 of CO2. While this is a mode that may gain and lose energy collisionally it is not infrared (IR) active as there is no transient electric dipole.

       

        

       Bending Mode V2

       The bending mode v2 of CO2, responsible for the 15.00 μm (wavenumber 667 cm-1) band -- the mode dominating the enhanced greenhouse effect and that primarily used by AIRS. This is infrared (IR) active due to a transient dipole: bending results in charge being asymmetrically distributed with net positive near the carbon atom and negative near the two oxygen atoms.

       

       And

       

        

       Asymmetic Stretching Mode V3

       The asymmetric stretching mode v3 of CO2 is responsible for the 4.26 μm (wavenumber of 2349 cm-1) band. The asymmetic stretch result in a net positive charge near the carbon atom and a net negative charge with the isolated oxygen atom, creating an electric dipole and making it infrared (IR) active. Given the range of atmospheric temperatures and concentrations of CO2 the bending mode v2 plays a greater role in climate change.

       

42449. Daniel Bailey at 11:50 AM on 31 August 2013
       Greenhouse Effect Basics: Warm Earth, Cold Atmosphere
       

       It might be helpful to visualize the various vibrational modes of CO2 with these animated GIFs:

         Asymmetric

         Bending 

         Symmetric

42450. Phil at 07:18 AM on 31 August 2013
       Greenhouse Effect Basics: Warm Earth, Cold Atmosphere
       

       MThompson @81. I think you are both right and wrong. The asymmetric stretch is stronger than the bend, however the important fact you are missing is the distribution of IR radiation emitted by planet Earth. This is a (near) black body distribution, and the peak (at 288K) almost co-incides with the CO2 bend. Thus the bend plays a more important role simply because there is more radiation in the Earths emission spectrum to absorb.

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