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Comments 124401 to 124450:

124401. VeryTallGuy at 07:46 AM on 9 February 2010
        Working out future sea level rise from the past
        By my very rough reading of the graph we have: Maximum rate of rise at the end of glaciation = 10mm/yr (40m in 4000 years) Rate this century predicted by AR4 = 1.8 - 5.9mm/yr Rate this century including best understanding of ice sheet dynamics = 7.5 - 20mm/yr Current rate (satellite data) = 3mm/yr Which prompts a couple of questions: 1) When could we reasonably expect to see a statistically significant rise in rate of sea level measurements ? 2) It's really the rate of warming that matters, not it's magnitude (even 6 degrees over a few million years wouldn't matter much). What is the maximum rate of rise we can cope with without huge disruption ?
124402. Russ_Brown at 06:52 AM on 9 February 2010
        The role of stratospheric water vapor in global warming
        Solomon et al state: "However, the trend in global surface temperature has been nearly flat since the late 1990's despite continuing increases in the forcing due to the sum of the well-mixed greenhouse gases (CO2, CH4, halocarbons, and N2O), raising questions regarding the understanding of forced climate change." The mean temperature increments (relative to the reference level) were: +0.46 deg C for '95-99 +0.57 deg C for '00-04 +0.68 deg C for '05-09 The rate of change was not "nearly flat".
124403. Doug Bostrom at 06:26 AM on 9 February 2010
        Working out future sea level rise from the past
        Further to Geo Guy and CBDunkerson, here's an interesting snippet from the just-past AGU meeting discussing some underlying details (pun, sorry!). Look for "Antarctic Glacier Off Its Leash": Pine Island Glacier Geo Guy, timing of the eccentricity versus seasons counts for much.
124404. Riccardo at 05:31 AM on 9 February 2010
        Increasing CO2 has little to no effect
        matt sykes, i forgot to add that in any case absorption of sunlight is included in the radiative transfer codes.
124405. Riccardo at 05:10 AM on 9 February 2010
        Increasing CO2 has little to no effect
        matt sykes, from about 2 to 8 microns IR from the sun is absorbed by water vapour, CO2 has no influence. Also, you still integrate over the whole IR, not just the CO2 bands. At 15 microns, instead, the atmosphere is transparent and the CO2 band is centered at the peak of the thermal emission, the overall effect is then larger. Go back to your Plank calculator but this time plugin in the right numbers for a meaningfull comparison. The visible is 0.4-0.8 microns, the CO2 absorbtion band is centered at 15 micron and with a width of 2 microns (14-16 microns, in reality it is much narrower than this). You end up with a ratio of the energy coming from the sun in the CO2 related absorption band and the visible of the order of 10^-4. Negligible. #6 In this very same post you can see absorption from CO2, you must be wrong. Indeed, the radiation abosrbed is re-emitted isotropically and part of it will be converted directly into heat in the atmosphere. At the top of the atmosphere you will see less radiation. I'd suggest to read how an idealized model works.
124406. CBDunkerson at 04:41 AM on 9 February 2010
        Working out future sea level rise from the past
        Geo Guy, you've got your terminology slightly off. ice SHEET - Ice resting on land. ice SHELF - Ice floating on water. The breakup of floating ice shelves does not raise sea levels. The collapse of ice sheets off of land and into the oceans does. Berenyi, since your comment seems to have nothing to do with the article above I'll assume you are still objecting to John's statement in the prior article that climate sensitivity applies to both internal and external forcings. In your response here you argue that forcings are different. Congratulations, that is true. However, an orbital eccentricity which causes arctic sea ice to melt is going to have exactly the same climate sensitivity as warm ocean currents melting that arctic sea ice... or CO2 induced warming. The feedback effect, melting arctic sea ice decreasing the planet's albedo, has the same sensitivity regardless of what forcing is driving it.
124407. Doug Bostrom at 04:37 AM on 9 February 2010
        The role of stratospheric water vapor in global warming
        Berényi Péter at 03:45 AM on 9 February, 2010 That's a fascinating experiment and one I think would be fun to do with my son. Changing some of the properties and watching what happens to the distribution would be pretty interesting. But the system you describe is in equilibrium; the aperture the sand is passing through is constant, the gravitation is constant, the granule size is constant. How does it apply to the case under discussion here? I don't follow the analogy but it could be I'm just dense.
124408. CBDunkerson at 04:34 AM on 9 February 2010
        Could climate shifts be causing global warming?
        Berenyi wrote: "Albedo is supposed to be connected to short wave absorptivity while the emissivity you are talking about is in thermal infrared. They are very different beasts (5778 K vs. 255 K)." First, 5778 K and 255 K are the effective temperatures of the Sun and Earth, as determined by the wavelengths of radiation which they emit. The short wave radiation (aka 'visible light') from the Sun which is not reflected (based on the albedo of the Earth) is instead absorbed, heats the absorbing material, and is thus re-emitted as the thermal infrared radiation you describe as a 'very different beast'. The incoming and outgoing radiation are intrinsically linked regardless of the shift in wavelength... and I'm not sure why you are suggesting otherwise. The changing composition of the Earth's atmosphere is obviously causing changes in its emissivity... indeed, this effect has been measured down to the level of being able to determine the specific wavelengths impacted. Your argument that it is impossible for atmospheric emissivity to change given the LTE of the lower atmosphere is incorrect because LTE refers to equilibrium of the actual MASS of the atmosphere... photons absorbed and re-emitted by the electromagnetic fields of the greenhouse gases may pass through the LTE without impacting it at all.
124409. Doug Bostrom at 04:12 AM on 9 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        Charlie A at 19:31 PM on 8 February, 2010 "The IPCC could have avoided most of the mentioned problems with a couple interns or grad students working as "fact checkers". The fact checker job is simply to see that each statement is supported by original source material." Perhaps a bit more than a couple of interns. This is a critical document and really does need to be reliable. I've not gone over the review process in detail so I'm speculating just a bit here, but from what I've learned of the Himalaya glacier business it seems that the chain of command on the review process petered out, not leading to an editor with sole focus on quality control but instead to a multi-tasking professional with primary responsibilities in another arena. I'm acquainted as the proverbial fly on the wall with the role of volunteer peer editors (where the scientifically important editing is done) in the academic publication process. That duty is very demanding and picky, requires a lot of time to be done right and yet is shoehorned into the middle of an active career ipso facto. People asked to be editors are generally productive researchers so it's almost axiomatic they are overcommitted individuals. So (harumph) if -I- were running the process I'd make sure there was a single person for each domain section of the report with an existential interest in making sure the quality control you mention was completed properly. A bit of a conundrum, because that person is going to need a good general grasp of the field in question yet will need to devote slavish attention to the task at hand. Perhaps this could be a career candle for emeritus professors? Unfortunately many of those tend to continue publishing until they drop dead, but after all this is a distinguished publication, akin to a literature review or compendium book.
124410. Geo Guy at 04:08 AM on 9 February 2010
        Working out future sea level rise from the past
        There are two points I want to make. First of all, ice sheets such as those that have broken off from Antarctica have a nil effect on the sea levels when they melt because the weight of the ice has already displace the water it is floating on. As for the constant moving of ice such as can be observed in Alaska, the motion is a regular part of the glacial activity and takes place when the mass of the glacier in its middle, increases, forcing the glacier to spread out towards its extremities. Secondly when the orbit of a body becomes more elliptical, then there are sections of the orbit that are further from the sun than they would be if the orbit was circular and hence would be further from the son when positioned at the long elliptical axis.
124411. Berényi Péter at 03:45 AM on 9 February 2010
        The role of stratospheric water vapor in global warming
        doug_bostrom at 04:26 AM on 6 February, 2010 "To make a case for that you need to show it with details" OK. Self Organized Criticality (SOC) describes the Climate/Weather system's state well. It is a non equilibrium thermodynamic system with a huge input stream of exergy. Sandpile Avalanche Dynamics is a simple (understandable) conceptual model of such systems. There is a table on a digital scale which records the weight as a time series. A container above, with a tiny hole on the bottom is full of dry sand. The sand slowly piles up on the table. As soon as the pile gets too steep, some sand shifts down to the bottom in an avalanche. Sooner or later the table gets "saturated", avalances go over the edge, sand sprays to the floor. It is swept up and put back to the container. The sytem gets into a "steady state", the weight fluctuates around an equilibrium value. However, the statistics of the time series is far from trivial. One has avalanches of all sizes, small and large, the magnitude distribution following a power law. Epochs of gradual increase are followed by sudden drops of variable size. If you apply "Standard Normal Homogeneity Test" (SNTH), identify discontinuities, adjust time series accordingly, you are left with an ever increasing sandpile on the table, defying common sense. The reason is that dynamics is not symmetric to time reversal. In this respect it is same as climate. Detailed enough?
124412. Berényi Péter at 02:59 AM on 9 February 2010
        Working out future sea level rise from the past
        Orbital eccentricity variations has no effect on annual average "solar radiative forcing". It is only the seasonal distribution of incoming radiation which changes. Depending on the phase, it can make northern summers warmer than average and winters colder. Or the other way around. Carbon dioxide has no such seasonal effect, or, if anything, it makes seasons more even. The two "forcings" are not comparable.
124413. HumanityRules at 01:55 AM on 9 February 2010
        Could climate shifts be causing global warming?
        There seems to be two separate experiments expressed in the three papers and I'm not sure they are related. Tsonis et al 2007 and Swanson & Tsonis 2009 develop the idea of syncronised NH climate. (Source for fig 1) While Swanson & Tsonis 2009 uses preexisting climate models to extract the 'natural variability" in the climate (source for fig 2) Strangley Swanson & Tsonis 2009 doesn't reference any of the science in either of the other two papers, only picking out a comment about policy implications. In what way does the finding in Swanson & Tsonis 2009 (i.e. Fig 2) rely on the identification of syncronisation in the other two papers? It looks to me not at all. All Swanson & Tsonis 2009 does is pick apart natural and anthropogenic temperature change based on older climate models. While the synchronisation theory suggests that climate over the whole of teh NH are at times linked. The paper trying to tease out the natural variability signal could only identify this in two regions (tropical Pacific and the North Atlantic). John could you explain why you link the work in Fig1 directly to Fig 2 when the original authors make no attempt to do this?
124414. ConcernedCitizen at 01:32 AM on 9 February 2010
        Increasing CO2 has little to no effect
        @Ricardo. Just found an online Plank law calculator. For wavelenghts betweem 3.9 and 4.1 microns the sun produces 340,000 times as much energy as the earth. This is close to my orevious estimate of 400,000. So, what does all this SOlar IR energy do in the atmosphere in comparison to terrestrial IR? Is it blocked in the uper atmosphere, does it saturate the CO2? Is it absorbed and re-emmitted into space in tha same way as terrestrial IR is absorbed and re-emmitted to the surface? If so, and given that it is 400,000 times stronger the effect of CO2 is to actually reduce the IR at the surface, not increase it.
124415. ConcernedCitizen at 01:18 AM on 9 February 2010
        Increasing CO2 has little to no effect
        #3 2, 4.3 and 15 microns in fact. The first of which is well inside the graph I linked to. This one shows even more clearly how cooler bodies release less IR than hotter ones. http://quantumfreak.com/wp-content/uploads/2008/09/black-body-radiation-curves.png Mind you, this isnt surprising. A piece of metal at 30 `C will be warmer to the hand than one at 20`C becaue it is producing more IR. As for calculating the IR of a particular frequency emitted by an object at a particular frequency, I dont know how to, perhaps you could direct me to the relevant formula althogh I think we have establisged that hotter bodies do produce more IR than cooler ones. #4. You said "You clearly still get cooling at night but not all of the energy absorbed during the day" I understodd this to mean that the energy absorbed during the day cane be entirely lost at night. If you meant something else then I appologise for misunderstanding you although my understanding seems logical still. #5 And there is clearly something else at play in the Arctic too since it is only as warm as it was in the 1930's. But, thats the complexity of climate! #6 But you cant fell from space what is happening to the energy absorbed by CO2. It is either re-emmitted at the same frequency and thus bounces around the atmosphere fomr mollecule to mollecule or it is emmitted as broad band radiation in which case all of it except the 8% absorbed by CO2 will end up released to space. So from a sensor looking down from space you will never see the CO2 absorbed energy, ie those banmds will be missing from the spectrum, regardless of the re-emmission mathod. However, if the re-emission is of broad band, ie black body radiation, than CO2 effectively converts narrow band to broad band radiation. This will increase the levels of non absorbed energy transmitted to space, which is what one of the other respondants above stated had occured in the later sattelite measurement.
124416. oracle2world at 00:59 AM on 9 February 2010
        Could climate shifts be causing global warming?
        This isn't exactly much of an argument against man-made global warming. Folks need to move on to the more robust ones.
124417. Arkadiusz Semczyszak at 00:11 AM on 9 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        "avorite" - favorite obvious
124418. Arkadiusz Semczyszak at 00:09 AM on 9 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        My job is agro-meteorology. I think warming it’s positive - in sum, for agriculture - in global. Let's do the simplest analysis of the older "warm-up’s", for example, based on the (above-mentioned) book by Stanley: 1. The higher the temperature (f. e. more than 2 deg more than now) that the greater part of the Earth's surface, are similar ecosystems. 2. The higher the temperature - the weaker zoning plant. 3. The higher the temperature - the less the deserts ... 4. Conclusion: The higher the temperature the more anticyclones (smaller pressure gradient?); increasing the area covered by a thick layer of cirrocumulus - tropical and maybe subtropical thermostat? Warming Climate is simpler in operation? P.S. Important observation: Changes are not linear: my "avorite" example - Mongolia - current warming: It takes 60-80 years there is drought, when the former was about 1 deg warmer than now, reaching there monsoons ...
124419. Berényi Péter at 23:41 PM on 8 February 2010
        Could climate shifts be causing global warming?
        CBDunkerson at 22:24 PM on 8 February, 2010: "the emissivity of the Earth's atmosphere has decreased due primarily to the increase in carbon dioxide" Wait a minute. Albedo is supposed to be connected to short wave absorptivity while the emissivity you are talking about is in thermal infrared. They are very different beasts (5778 K vs. 255 K). So. Are you telling us that overall IR emissivity of Earth is decreasing due to GHGs? It would be interesting, since atmosphere below 50 km (30 miles) is in LTE (Local Thermodynamic Equilibrium). In LTE emissivity is equal to absorptivity, according to Kirchhoff's law. If emissivity is decreasing, absorptivity should do the same. It leads us to the conclusion, that GHGs make atmospheric absorptivity LESS, a contradiction in terms. Think again, please.
124420. Riccardo at 23:26 PM on 8 February 2010
        Increasing CO2 has little to no effect
        matt sykes, #3 the effect of CO2 is mainly on the band at about 700 cm^-1 or about 15 microns while the graph you show ends at 3 microns. Also, cosider that the absorption band is relatively narrow, it's really a tiny fraction. It'd be good if you calculate it yourself approximating the incoming radiation with the Plank formula, it will probably be more convincing than my words. #4 i did not say that "it takes more than 12 hours for a photon on average to exit the atmosphere to space.". Would it be so long you couldn't have significant day/night temperature variation; just the opposite is true. The warming of the poles depends on a lot of things, not least on atmospheric and oceanic circulation. Antarctica is "isolated" both by the Antarctic Circumpolar Current and by the strong westerly winds blowing in the Southern Oceans. No one expect the same warming as in the Arctic. I do not any rough figure on the ratio between collisional and radiative de-excitation. It quite complicated and it also depends on density and temperature. You can estimate the overall effect in the atmosphere from the ratio of the energy leaving the atmosphere over energy emitted by the surface. You last claim is definitely not true as can be easily seen in the absorption spectra of CO2 from space. Indeed, at the surface level the absorption lenth is pretty short, no way to escape directly to space.
124421. Arkadiusz Semczyszak at 22:55 PM on 8 February 2010
        Could climate shifts be causing global warming?
        1. In the context of the Swanson’s paper, is interesting this work: "Persistent Positive North Atlantic Oscillation Mode Dominated the Medieval Climate Anomaly", Trouet V. et al., 2009. "According to Trouet, a Pacific La Niña mode and a positive NAO mode could have reinforced each other in a positive feedback loop – and this could explain the stability of the medieval climate anomaly." - says one comment. La Niña ... = cool ocean = Emiliana huxleyi less and less DMS = less clouds = more heat of summer, for example as in 2003 and 2006 year (Europe)... ? 2. Human development - AGW - positive feedback in response on a natural warming? Very interesting theory ... but it has already had formerly Pielke senior. 3. Marcus say: "today, with the largest magnitude & rate of change we've seen in all of human history." This is not true. I recall once again the work of a Al Gore friend’s - L. Thompson's: "Abrupt tropical climate change: Past and Present". (proxies f. e.: delta 18O until 2003, Quelccaya). The current temperature increase is maybe unprecedented, but the former changes were violent. P.S. In Poland, the loading (abnormally long) very cold winter ...
124422. ConcernedCitizen at 22:41 PM on 8 February 2010
        Increasing CO2 has little to no effect
        Sorry, final quesuiton, you say CO2 can release energy as a photon or by direct warming of other molecules. Do you have any figures for the rough percentage of energy released by each meathod? Given CO2s absorbiton band is only 8% of the total IR spectrum 92% of any release as a black body would not be re-absorbed by another CO2 molecule and thus exit the atmosphere directly.
124423. ConcernedCitizen at 22:36 PM on 8 February 2010
        Increasing CO2 has little to no effect
        @Ricardo. #2 OK, lets ignore thins since no one understands my quesiton. #3 According to this, http://en.wikipedia.org/wiki/File:Blackbody-lg.png, the sun emmits far more IR then the earth at the frequencies absorbbed by CO2. Surely all this IR saturates the CO2 in the atmopshere with energy, dwarfing the IR coning form the earth? #4 OK, so you say that the CO2 primarially rleases energy as a photon of light at the same frequency it absorbed it at, and that due toi the volume of CO2 it takes more than 12 hours for a photon on average to exit the atmosphere to space. Interesting you mention the moon, its daytime high is 105`c. Is it not the case that the reason the earth has a lower daytime high is because gasses in the atmosphere, including CO2, reduce the energy that strikes the surface? As for the throry of GH gas warming dont forget the poles are supposed to warm the most, but in fact only one of them is warming, so it seems the planet earth also has a problem with the theory. I am however prepared ot accept that I am in deed missing somehting, hence asking these quesitons.
124424. CBDunkerson at 22:24 PM on 8 February 2010
        Could climate shifts be causing global warming?
        Berenyi, your starting premise is redundant and incorrect. effective temperature = [(luminosity of star * (1 - albedo)) / (16 * pi * Stefan's constant * distance from star^2)]^(1/4) That is, effective temperature is the black body absorption temperature of the planet adjusted by its albedo and differing from ACTUAL temperature in that it ignores emissivity (from atmosphere and internal heat). Thus, changing albedo changes effective temperature... making your either/or scenario inaccurate, not to mention incomplete since it leaves out the actual primary driver in this case, the changing emissivity of the Earth's atmosphere. Analysis of the decrease in OLR shows that it is heavily focused within the wavelengths of radiation which are absorbed by water vapor and carbon dioxide... in short, the emissivity of the Earth's atmosphere has decreased due primarily to the increase in carbon dioxide and the positive feedback effect that has with water vapor. That said, the albedo of the planet is also decreasing (and thus the effective temperature increasing) as ice melts... another positive feedback impact from the increased temperatures driven by the CO2 increase.
124425. Berényi Péter at 21:12 PM on 8 February 2010
        Could climate shifts be causing global warming?
        guys, I would like to have a straightforward answer to a simple question. If the climate system is in energetic imbalance indeed, that is OLR (Outgoing Longwave Radiation) is less than ASR (Absorbed Shortwave radiation) as a consecquence of increasing carbon dioxid contents of the atmosphere, it can happen in two ways. Either effective temperature or albedo of Earth (as seen from space) is decreasing. Which one?
124426. Charlie A at 19:31 PM on 8 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        Doug_Bostrom, I agree with most of your last comment but there is no need to make it more complicated than necessary. The IPCC could have avoided most of the mentioned problems with a couple interns or grad students working as "fact checkers". The fact checker job is simply to see that each statement is supported by original source material. The problems have been that the IPCC assessment and synthesis document has too often relied upon other synthesis and assessment documents -- whether or not those were peer reviewed, or papers from conservation groups, or by environmentalist activist groups. When we trace back from IPCC to a WWF assessment paper to another assessment paper and through one or more steps before finally getting back to the orignal source, we find that the final statements in IPCC don't correspond to that of the original source. In other words, I don't see it as a grey vs peer reviewed problem, but as original vs hearsay.
124427. Doug Bostrom at 17:58 PM on 8 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        One more (I doubt it, actually) thought about peer reviewed research versus "grey literature." Discussion around climate science per se is dominated by peer reviewed research publications. That's as it should be; this is scientific research and publication via peer scrutiny has proven to be a generally robust and productive way of eliminating weak bricks from the ever growing tower of knowledge. However, when it comes to impacts of climate change we begin to see a transition from pure research into operational activities. For instance, predictions of hydrological changes are or at least should be rooted in scientific research, but those findings are handed off for application into the purview of people practicing engineering and agronomy. Although pure research on climate change impacts is and will continue to be conducted in those arenas, at some point research gives way to practicum and there's where the system of peer review will disappear. Scientists doing research are not engineers and farmers; they will not and should not be people plugging numbers into known equations and producing answers. Just so, practicing engineers and agricultural extension experts will be concerned with processing integrations of climate change impacts into products for their customers; practicing experts do and can not resort to peer review before responding to solicitations for bids or requests for crop planting advice. Yet engineers and farmers will have much that is valuable to say about climate change impacts. Indeed, it is not going to be possible to assign numerical values to the costs or opportunities of climate change without tapping these people and their practical experience. For that matter, this is true of many conservation organizations, even including the hapless WWF. Many of these are project oriented organizations concerned with practical results yet they have valuable observations to contribute. Clearly the exact process of integrating disparate sources of information into IPCC reports was not perfected prior to the 2007 report. As a wag here on Skeptical Science elliptically pointed out, the WG2 report included "grey literature" which has leaked into peer reviewed literature because not everybody received the memo that WG2 explicitly permitted grey literature. Allowing grey literature means that material intended for popular audiences found its way into the WG2 report, and some of this has experienced what IT security folks call "privilege escalation"; popularized and what one must admit may even be sensationalized descriptions of scientific findings have found themselves blinking in the harsh light of scientific literature where they are found damaging to precious credibility. I don't think they are a hazard to actual science itself, as attempting to use this material for conceptual underpinnings would quickly reveal the shoddy nature of the material. I hope when IPCC tweaks its inputs it does not commit the mistake of disallowing all so-called "grey literature". To do so would be throwing out the baby with the bathwater; there is too much useful expertise outside of the academic arena to ignore. At the same time the material that does get in is going to need passing through a very fine and particular sieve. And somehow IPCC must clearly telegraph what is suitable for citations lest we have more embarrassments such as the unfortunate Kehrwald et al, where decent research is dulled by duff citations.
124428. Timothy Chase at 17:52 PM on 8 February 2010
        Could climate shifts be causing global warming?
        John, you stated in your essay, "Another issue discussed in Swanson 2009 is that if climate is more sensitive to internal variability than currently thought, this would also mean climate is more sensitive to imposed forcings. This includes radiative forcings such as a warming sun, cooling from sulfate aerosols or warming from CO2. This leads to a crucial question that the authors themselves raise but don't answer..." Obviously this is a serious problem for their explanation of twentieth century climate change -- as they understand it. However, if the reorganization of the climate mode network that results in the shift from one climate regime (attractor) to another is to a first approximation a predictable response to a change in radiative forcing, then the sensitivity to internal variability need not be at the expense of a sensitivity to external forcing. Rather, the sensitivity to internal variability might very well be part of the mechanism through which sensitivity to external forcing is expressed.
124429. Timothy Chase at 17:35 PM on 8 February 2010
        Could climate shifts be causing global warming?
        John, One passage that comes to mind for me in the context of Tsonis and Swanson is the following, "A crucial question in the global-warming debate concerns the extent to which recent climate change is caused by anthropogenic forcing or is a manifestation of natural climate variability. It is commonly thought that the climate response to anthropogenic forcing should be distinct from the patterns of natural climate variability. But, on the basis of studies of nonlinear chaotic models with preferred states or 'regimes', it has been argued, that the spatial patterns of the response to anthropogenic forcing may in fact project principally onto modes of natural climate variability." Signature of recent climate change in frequencies of natural atmospheric circulation regimes S. Corti, F. Molteni, and T. N. Palmer Nature 398, 799-802 (29 April 1999) http://www.nature.com/nature/journal/v398/n6730/abs/398799a0.html Why is it that Tsonis and Swanson believe that shifts in climate regimes happen independently of the net forcing? If what we are dealing with is a chaotic system that is especially sensitive to boundary conditions, which in this case would be to a first approximation the net forcing being imposed upon the climate system, wouldn't it make sense that when the forcing changes the climate regimes change as well? I always think of the reflective sulfates from fossil fuel combustion. Of course the clean air laws that reduced aerosols and their effects during the 1970s didn't change emissions overnight. However, chaotic systems are subject to step -like behavior -- and I would presume that the suddenness of the shift from one climate regime could simply be a result of that. After all, one of the characteristics of chaotic systems is their extreme sensitivity to their environment. But at the level of the attractor (or "regime") this needn't be a mere function of internal variability but may be a more or less predictable response to the environment. If this were the case, I would presume that the same sort of reorganization in the climate mode network would be observed in the shift from one climate regime to another that Tsonis and Swanson see, but the reorganization would itself be a result of the change in the forcing -- natural or anthropogenic.
124430. Marcus at 16:28 PM on 8 February 2010
        Could climate shifts be causing global warming?
        Actually, at least on the methane-hydrate side of things, it seems we might have more time than we first thought. According to CSIRO research, the temperature rise needed to melt the methane-hydrate crystals is higher than first thought. That's cold comfort for me though!
124431. Bern at 15:06 PM on 8 February 2010
        Could climate shifts be causing global warming?
        "but it may also be anthropomorphic CH 4 that triggers the short term disaster" Haha! That brought to mind visions of cheesy 70s Dr Who man-in-a-rubber-suit monsters made of methane-hydrate crystals... :-)
124432. Doug Bostrom at 15:02 PM on 8 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        Just to clarify, it's fairly obvious that IPCC agricultural projections were not produced "without any supporting data", unless one is prepared to say that agronomists producing reports for governments are no different than cursory speculations driven by newspaper articles.
124433. Doug Bostrom at 14:58 PM on 8 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        From the Times article: "The claims in the Synthesis Report go back to the IPCC’s report on the global impacts of climate change. It warns that all Africa faces a long-term threat from farmland turning to desert and then says of north Africa, “additional risks that could be exacerbated by climate change include greater erosion, deficiencies in yields from rain-fed agriculture of up to 50% during the 2000-20 period, and reductions in crop growth period (Agoumi, 2003)”." The Times goes on to point out that estimates of future crop yields are derived from governmental assessments, which are not peer reviewed. I think one of the challenges for upcoming improvements to IPCC reports will be figuring out what non-peer reviewed material will acceptable for inclusion. Clearly much important work is done by governments that is not peer reviewed yet found generally acceptable for planning purposes. To exclude all such material does not seem very wise. This seems particularly true of impact assessments. As to the fundamentals of climate change, a different matter; any projections of impacts etc. ought be driven by the best science possible, even where academic resources are insufficient to supplant the rather enormous amount of technical expertise to be found in governmental agricultural ministries and the like.
124434. Charlie A at 14:45 PM on 8 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        The IPCC, on page 50, section 3.3.2 of the AR4 Synthesis report has a bulleted item that reads "By 2020, in some countries, yields from rain-fed agriculture could be reduced by up to 50%. Agricultural production, including access to food, in many African countries is projected to be severely compromised." As this is in the section about the effects of climate change on regions, one must assume that this is an IPCC claim about climate change and/or anthropogenically triggered climate change. The current chairman of the IPCC Working Group 2 has reviewed the documentation and says that this finding is not supported in any IPCC documentation or references. Making of such unsupported statements is, in itself, a problem. It is even more so if there are no reliable studies that support such findings. None of the studies posted in comments in this blog are relevant to the IPCC statement. It would be helpful is someone could point to some studies that actually support the IPCC statement. These may, or may not exist. ------------------------------- The cassava study and the clover study are not relevant to the 50% reduction in crop yield in Africa by 2020. David Horton says "Southern Africa is in a similar geographical situation to Australia, and I'm betting science bodies there are making the same grim projections." IPCC seems to also have been "betting" that the grim projections would be accepted without any supporting data. Until recently, they were.
124435. David Horton at 14:19 PM on 8 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        99% is good angliss, but my point was that there was, is, no reason to say "So the 2020 date is probably messed up". It might be spot on, it might not be, there is no way of knowing, and in any case a particular year isn't the point. But saying it is "probably messed up" without evidence for (or against) this statement is just giving credence to the hordes of deniers who are pushing the idea that all IPCC projections are "messed up".
124436. angliss at 13:24 PM on 8 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        David, clearly you don't know who your friends are, given I was supporting you 99%. Way to focus on that 1%. Charlie, try "90% reduction in cassava yields." Try cassava becoming poisonous due to increased cyanogen compounds (yes, those are compounds that your digestive system turns into the poison cyanide). Agriculture includes raising livestock, Charlie. From the M-W definition here: http://www.merriam-webster.com/dictionary/agriculture agriculture is "the science, art, or practice of cultivating the soil, producing crops, and raising livestock and in varying degrees the preparation and marketing of the resulting products" So if you make all that white clover poisonous and kill the livestock, then that is a "reduction in yield." Maybe the 2020 year is indefensible - I don't know, although the current projections for CO2 emissions are high enough that it could be. But focusing on a single date instead of the underlying science is a straw man. Try something serious next time.
124437. robbrian at 12:46 PM on 8 February 2010
        Could climate shifts be causing global warming?
        I'm sorry I meant anthropogenic
        Response: You're not the first to make that mistake and you won't be the last :-)
124438. robbrian at 12:38 PM on 8 February 2010
        Could climate shifts be causing global warming?
        Tony O'Brien, If we're lucky we have that much time. I have yet to see a real analysis of the impact of the oxidation of methane gas on the rise of CO 2 in the atmosphere. Nor have I seen credible anaysis of the methane hydrate dissociation effect around Lake Baikal, The Beaufort Sea, and other areas where extensive oil and gas drilling have deposited millions of gallons of steam and fresh water under the crust to pressurize wells and bore holes. These hydrates by definition can only form in the presence of fresh water. The oil folks found that out during WWII when their pipes would clog with ch4, and later in the last century when rigs would be destroyed by "mysterious explsions." It may well be CO 2 that does us in in the long run, but it may also be anthropomorphic CH 4 that triggers the short term disaster.
124439. Bern at 12:33 PM on 8 February 2010
        Could climate shifts be causing global warming?
        Tony O'Brien at : It might be 10 years, it might be 15 or 20, or, as suggested earlier, arctic ice melt might be reaching a tipping point (or have already passed it) and it might happen a whole lot sooner. Either way, this research helps our understanding of how the Earth's climate behaves, and will improve future model predictions. In terms of seeing actual impacts from warming, I noticed this story on the ABC News site this morning, suggesting that increased snowfall in East Antarctica is tied to a prolonged and severe drought in the south-west corner of Australia, and that this change is driven by global warming.
124440. Tony O at 11:56 AM on 8 February 2010
        Could climate shifts be causing global warming?
        Just as I think I am starting to get a handle on global climate change something new comes along. However it does fit. This paper fills the gap between sudden changes observed and gradual increases scientists like to show. If I understand correctly (always doubtful), we have about ten years before it hits the fan again.
124441. Doug Bostrom at 10:57 AM on 8 February 2010
        Lessons from the Monckton/Plimer debate
        acrim at 08:36 AM on 8 February, 2010 "The proxy evidence agrees with PMOD because Frohlich and Lean used the proxy models to make umjustified alterations in the TSI data to agree with those models. This simple fact is frequently glossed over in these discussions! " I'm sorry but I can't take just take your word for it, I don't even know who you are. If they are simple fact, presumably you can explain these "unjustified alterations" here? SkepticalScience of course has already been over this, drawing this conclusion: "What relevance does this have for the global warming debate? Not terribly much. We're talking about a very slight warming sun versus a very slight cooling sun. Either TSI reconstruction show a stark break down in correlation between sun and climate in the mid 1970's."
124442. David Horton at 10:19 AM on 8 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        For those interested, the report on shifting agriculture to northern Australia http://www.abc.net.au/news/stories/2010/02/08/2812753.htm?section=justin has just appeared. No go, says the committee.
124443. Charlie A at 10:05 AM on 8 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        I fail to see how the papers regarding clover grown in 700ppm CO2 relates to the UN assertion of 50% reduction in yield by 2020 in rain-fed agriculture in Africa. Chris Field, the current co-chair of IPCC WG2 fails to find any evidence to support those claims either. http://www.timesonline.co.uk/tol/news/environment/article7017907.ece
124444. Cliff Oates at 09:50 AM on 8 February 2010
        It's the sun
        The problem of correlating the earth's global temperatures with observed driving factors is complex at best. Our weather is dominated by the oceans. These comprise 70 percent of the globe surface and represent a tremendous heat sink which is circulating continuously. As such we would expect that observed temperatures would have an appreciable time lag behind the driving factors.I would expect the time lag to be more than two solar cycles. Any calculation of the earth’s thermal balance would have to include a deep understanding of the interaction of the solar radiation with the ocean areas. The past observations of long term global shifts (the medieval warming and the little ice age) would suggest that the sun’s variation has caused large temperature changes in the past. In examining sunspot average numbers with smoothing filters of 25 to 30 years shows a significant increase from 1920 to 1970. Could that be a cause of the global temperature increase? Sunspots not only affect the total radiant energy, but also the frequency distribution. Also since oceans comprise 70 percent of the globe surface, are land measurements a true indication of global temperatures? I believe that ascribing the global temperature increase to the effects of greenhouse gasses is a vastly simplified solution to a very complex problem.
        Response:

        You make some good points. Yes, there is a climate lag. An important point to realise is that the lag doesn't mean there's a gap between a forcing (eg - warming sun) and the climate response. Climate responds immediately to a forcing. The lag refers to the time it takes for the climate to reach equilibrium after an imposed forcing.
        
        For example, say the sun warms. As the sun warms, there is more energy coming into our planet than escaping back to space, so the planet starts accumulating heat and warms. Eventually the sun stops warming. At this point, there is still more energy coming in than radiating back to space so the planet continues to warm. As the planet warms, it radiates more energy out to space. Eventually the energy out increases to match the energy coming back in and the planet is in equilibrium again. The time it takes for the planet to reach equilibrium is the climate lag.
        
        Currently what is happening is the planet's energy imbalance is increasing. We are not approaching equilibrium which is what you would expect if we were responding to an earlier period of warming sun. Instead, something else is causing less energy to escape out to space. Satellites measuring the radiation escaping out to space find that the less energy is occuring at the wavelengths that carbon dioxide absorb energy. So at a time when CO2 levels are reaching the highest levels in over 15 million years, we're also observing less energy escaping to space at the very wavelengths that CO2 absorb infrared radiation.
        
        These topics have been covered in previous posts. There is a post that goes into more detail re climate lag. We peruse the many papers that examine the possibility that the sun is causing global warming. You make a good point about the importance of oceans - not only do they comprise most of the Earth's surface, they also absorb most of the infrared radiation that is trapped by greenhouse gases. Consequently, a better metric for global warming is the planet's total heat content which includes all the heat accumulating in the oceans.
        
        

124445. Marcus at 09:46 AM on 8 February 2010
        Could climate shifts be causing global warming?
        Here's the point, as I see it. 30 years of solar irradiance, volcanic activity & ocean circulation data all point to conditions which should have brought on a modest, long-term *cooling* of the planet, yet instead we experienced a period of the most rapid warming since temperature records were first taken. Also, from what little study I've done on these matters, most natural climate shifts usually take place over centuries (like the Medieval Warm Period & Little Ice Age, which both occurred over multi-century time frames), & yet here we are, today, with the largest magnitude & rate of change we've seen in all of human history. Yet still there are those who are desperate to blame *anything* but the burning of fossil fuels for this situation!
124446. Riccardo at 09:18 AM on 8 February 2010
        Lessons from the Monckton/Plimer debate
        acrim, it is untrue that "Frohlich and Lean used the proxy models to make umjustified alterations in the TSI data to agree with those models.". Or better, it is only partly true and for sure there are no "unjustified" alterations. But probably you do not bother to read how PMOD is constructed and you're repeating something read somewhere else, otherwise you could have been more specific on the use of the proxy model.
124447. acrim at 08:36 AM on 8 February 2010
        Lessons from the Monckton/Plimer debate
        @Jesús Rosino: The proxy evidence agrees with PMOD because Frohlich and Lean used the proxy models to make umjustified alterations in the TSI data to agree with those models. This simple fact is frequently glossed over in these discussions!
124448. acrim at 08:31 AM on 8 February 2010
        Lessons from the Monckton/Plimer debate
        @Jesús Rosino: The proxy evidence agrees with PMOD because Frohlich and Lean used the proxy models to make umjustified alterations in the TSI data to agree with those models. This simple fact is frequently glossed over in these discussions!
124449. Riccardo at 08:21 AM on 8 February 2010
        It's cooling
        Pat T, simplification is a quite risky game. Thinking of a monotonic warming when a monotonic forcing is applied is such a game. Look at the instrumental record and you'll see many periods of no warming and yet overall the temperature has increased. From 2002 to 2009 all the yearly averaged temperatures are within about 0.14 °C, i.e. +/- 0.07 °C. This is what the numbers say, undisputable. But this is only the begining of the story, not the end. Next step is understand what those numbers mean. To do this you have to look at how temperature behaves. You'll soon discover that there's an interannual varibility of about +/- 0.1 °C and that, in turn, in ten years you can not (statistically) assess a trend lower than about 0.2 °C/decade. Look at this graph (thanks to Tamino); temperature fluctuates between the lower and the upper bounds. You can (statistacally) say that temperature is still following the trend line until it goes out of the bounds. We are not there, not even close. This is as far as the numbers are concerned. Then comes the physics, explained by John in this post. Not the numbers nor the physics make us think it's cooling.
124450. CBDunkerson at 07:42 AM on 8 February 2010
        Could climate shifts be causing global warming?
        thingadota, others have addressed most of your points as I would have, but there is one remaining I'd like to answer; "The point is, is that you can't infer that because internal variables are climate-sensitive, then 'imposed' forcings are." Please read my prior response again. This is not an inference. People are saying that climate sensitivity applies to both internal and external forcings because that is DEMONSTRABLY true. AIRS satellite data shows that over many years temperature shifts from many sources (El Nino, La Nina, volcanic dimming, GHG warming, et cetera) were consistently accompanied by shifts in atmospheric water vapor in line with climate models. The source of the warming is irrelevant to the climate sensitivity of the feedback effect. Ditto arctic sea ice albedo feedback. Ditto ocean CO2 absorption temperature feedback. Et cetera. In your own terminology, you are attempting to 'split' the 'effects of atmospheric heat from GHG forcing' from the 'effects of atmospheric heat from ocean heat transfer'... and that's just nonsense. Once the extra heat is in the atmosphere its effects are identical regardless of where it came from.

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