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Comments 124351 to 124400:

124351. 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.
124352. 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.
124353. 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.
124354. 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?
124355. 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.
124356. 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.
124357. 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.
124358. 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.
124359. 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!
124360. 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... :-)
124361. 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.
124362. 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.
124363. 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.
124364. 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".
124365. 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.
124366. 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 :-)
124367. 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.
124368. 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.
124369. 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.
124370. 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."
124371. 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.
124372. 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
124373. 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.
        
        

124374. 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!
124375. 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.
124376. 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!
124377. 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!
124378. 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.
124379. 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.
124380. Pat T at 07:22 AM on 8 February 2010
        It's cooling
        .....and GISS is Northern Hemisphere-biased. Either way, even the measures that put 2005 as the warmest put it at 0.01 deg C above 1998. I.e., about even. 1 year of natural variability offsetting 11 years of CO2 isn't "cherry picking one year." If it's "still warming" then the temperature should still be rising - rather than simply still warm relative to the recent past. The height analogy is a good one because the temperature has remained within a few tenths of a degree C below to, by some measures one hundredth of a degree above the 1998 mean. It's been flat. Perhaps it's been flat DESPITE natural forcings that ought to have pushed it down. So say that.
124381. Ned at 07:12 AM on 8 February 2010
        Could climate shifts be causing global warming?
        thingadonta writes: "All of this does not mean it is sensitive to trace greenhouse gas changes (<0.1% by volume), such as c02." I'd like to second Doug Bostrom's surprise at your inclusion of this. Is the small absolute magnitude of the concentration of CO2 in the atmosphere somehow relevant? That factoid is a common staple of unscientific denialist propaganda ("CO2 is only a tiny fraction of the atmosphere, so how can it cause warming?"). It's a bit surprising and disappointing to see it popping up here. If you are seriously uncertain about whether a trace gas could be responsible for a large radiative forcing, please consider the case of halocarbons (e.g., CFCs) which have a substantial radiative forcing from concentrations that are measured in parts per trillion: http://www.esrl.noaa.gov/research/themes/forcing/
124382. Ned at 07:00 AM on 8 February 2010
        Could climate shifts be causing global warming?
        RSVP writes: "In figure 2, it looks like you could take the portion of the curve between 1910 and 1950, cut, paste and align to about 1970 and things would match up. So over a similar period, roughly the same temperature increase is seen, and yet we are talking about two periods in human history where in the second, the volume of CO2 far exceeds the first, ergo... " ... ergo, you have trouble reading graphs? Just kidding. 1910 to 1950 is a 40-year period, during which the dashed line goes up by about 0.20C and the quadratic line goes up by a bit less than that. 1970 to 2000 is a 30-year period, during which the dashed line goes up by about 0.25C and the quadratic line goes up by a bit less than that. (In fact, the dashed line stops before 2000, so the 0.25C rise is in less than 30 years). In other words, the recent warming was both greater and more rapid. I hope that helps. Enjoy the rest of the weekend...
124383. slincoln_wx at 06:29 AM on 8 February 2010
        Could climate shifts be causing global warming?
        "We know, from the past, that climate is sensitive to solar variation, orbital changes, oceanic circulation and continental configuration. It may be sensitive to various internal variables, which may also include climate shifts, as discussed in Swanson 2009. All of this does not mean it is sensitive to trace greenhouse gas changes (<0.1% by volume), such as c02. " You are right in saying that the reasons you listed dont necessarily mean that CO2 causes climate changes. But that's a strawman argument, as those arent the reasons that CO2 is known to cause climate changes in the first place.
124384. slincoln_wx at 06:27 AM on 8 February 2010
        Could climate shifts be causing global warming?
        Doesn't this article still beg the question - wouldn't there have to be something to cause the climate shift? So isn't it likely the other way around... is climate change causing climate shifts?
124385. Doug Bostrom at 05:50 AM on 8 February 2010
        Could climate shifts be causing global warming?
        thingadonta at 05:03 AM on 8 February, 2010 "All of this does not mean [climate] is sensitive to trace greenhouse gas changes (<0.1% by volume), such as c02." Well, from that it looks as though you are rejecting what is known about thermal radiation physics, or at least how it applies to C02. If you hypothesize that thermal radiation physics are selectively wrong for the example of C02, you need to show how, don't you? Assuming you don't think our basic understanding of thermal radiation physics is incorrect and/or that our theoretical and empirical observations of what happens when C02 molecules are illuminated at various thermal wavelengths are incorrect, in order to dismiss C02's impact on climate you really need to explain how the climate could be insensitive to the outcome of C02's basic physical behaviors. Unless you're able to demonstrate how we have very fundamental misunderstandings about some very fundamental physics, you inevitably have to accept that net effect of C02 in the atmosphere is to retard the emission of thermal radiation from the top of the atmosphere at a staggeringly large power level. The numerical outcome of additional C02 in a single cm2 column of air reaching the top of the atmosphere may not seem impressive, but take the entire surface of the planet into consideration and it's a whole different ballgame. Knowing the behaviors of C02 with regard to thermal radiation, we can with a pleasingly high degree of confidence predict what will happen when the proportion of C02 in the atmosphere is changed. If C02 in the atmosphere is increased, it will more efficiently retard emission of thermal radiation at the top of the atmosphere. This is not controversial in the slightest. We have no indication that this top-of-atmosphere retardation of thermal emission by C02 is highly variable; unlike other effects having to so with ocean heat transport, solar variation, etc. it is a forcing that is constantly present. The amount of power involved here is beyond our intuitive numeracy to describe. Given sufficient time, there is really no conceivable way it will not affect the climate. If you say otherwise, you're not really credible unless you start at the beginning and show otherwise, in reasonable detail.
124386. padruig at 05:07 AM on 8 February 2010
        Could climate shifts be causing global warming?
        While Swanson et.al. is at the surface interesting, their hypothesis should be seen as a part of the modeling process and not a competing hypothesis to anthropogenic factors. Swanson wrote a guest article on RealClimate.org (Jul 2009) shortly after his GRL article publication in which he helps clarify the the contribution of his hypothesis to the greater area of study. "What do our results have to do with Global Warming, i.e., the century-scale response to greenhouse gas emissions? VERY LITTLE, contrary to claims that others have made on our behalf."
124387. RSVP at 05:06 AM on 8 February 2010
        Could climate shifts be causing global warming?
        In figure 2, it looks like you could take the portion of the curve between 1910 and 1950, cut, paste and align to about 1970 and things would match up. So over a similar period, roughly the same temperature increase is seen, and yet we are talking about two periods in human history where in the second, the volume of CO2 far exceeds the first, ergo...
124388. thingadonta at 05:03 AM on 8 February 2010
        Could climate shifts be causing global warming?
        re#5 The point is, is that you can't infer that because internal variables are climate-sensitive, then 'imposed' forcings are. This is a classic case of 'lumping'. 'Lumping' versus 'splitting' is a classic problem that plagues many disciplines , and I can see now it plagues climate science as well, and, as usual, the 'lumpers' don't even realise that they are making such (invalid) inferences, or probably even that they are 'lumpers'. (Most skeptics I would also suggest, tend to be 'splitters'). The discussion in Swanson 2009 that if internal variables are climate sensitive, then imposed forcings are climate sensitive, is an invalid inferance. John Cook sees no issue with this, so both he, and Swanson 2009, (and also probably the peers who reviewed the paper) are 'lumpers' as well (like most academics and public servants I have come across- ?a case of failure of peer review). To repeat: -automatically inferring that because internal climate variables may be climate sensitive, it means overall the climate is sensitive and/or all climate variables are sensitive, is an invalid inferance. Another example of invalid 'lumping' is eg: -inferring that because the climate has changed significantly in the past from other variables than c02(eg Medieval Warm Period), then climate must be also sensitive to C02-exactly the same case, as above, of invalid lumping. This is a completely invalid inferance. The climate can be sensitive to some internal and/or imposed variables, and not others. We know, from the past, that climate is sensitive to solar variation, orbital changes, oceanic circulation and continental configuration. It may be sensitive to various internal variables, which may also include climate shifts, as discussed in Swanson 2009. All of this does not mean it is sensitive to trace greenhouse gas changes (<0.1% by volume), such as c02.
124389. CBDunkerson at 02:26 AM on 8 February 2010
        Could climate shifts be causing global warming?
        Karl_from_Wylie, oceanic oscillations are neither newly discovered nor potentially more impactful on climate change than humans. If you read the article above carefully you will see that the issue at hand is whether they are responsible for the comparatively minor fluctuations observed around the ongoing long term human induced warming. Ranger, science has come a long way since the industrial revolution (let alone the middle ages). The fact that past generations could not determine the extent and cause of temperature changes in their time does not mean we cannot do so in ours. Measured variances in wavelengths of infrared radiation clearly show that the wavelengths associated with the CO2 greenhouse effect are responsible for recent warming. We're even making headway in figuring out the causes of those past climate shifts, but without direct observation (which would require a time machine) those are still in question. Also, CO2 from wildfires is insignificant compared to human industry... and the Sun plays an enormous (indeed the primary) role in determining the temperatures of the inner planets. However, the energy put out by the Sun isn't changing in any significant way. Indeed, it went down a minuscule amount while we experienced the steepest warming on record.
124390. Ranger at 01:55 AM on 8 February 2010
        Could climate shifts be causing global warming?
        What caused the warming when the Vikings settled England? What caused the Earth to cool again? What about co2 produced by uncontrolled wildfires for milliana? The earth will cool. The Sun has no effect on the Temps of the inner planets?
124391. CBDunkerson at 01:28 AM on 8 February 2010
        Could climate shifts be causing global warming?
        thingadonta, while some feedback effects may vary based on the type of forcing, most of the major factors would not. That is, regardless of whether the atmospheric temperature goes up due to CO2 accumulation, increased solar radiation, oceanic heat transfer, or a martian death beam slowly cooking the planet... we know that increased air temperatures will lead to increased atmospheric water vapor, and a significant positive temperature feedback effect from that. The ice albedo feedback is evidently more sensitive to shifts in northern insolation and water temperature, but even so if minor variations in ocean heat distribution were causing significant feedback in arctic sea ice coverage (supportive of high sensitivity for Tsonis and Swanson's results) then an overall increase in ocean heat would perforce show similarly high sensitivity. Ergo, the SOURCE of the forcing is often irrelevant to the imposed feedbacks and overall climate sensitivity. Heat is heat... where it came from doesn't change the effects it is going to have.
124392. Karl_from_Wylie at 01:19 AM on 8 February 2010
        Could climate shifts be causing global warming?
        A newly discovered cause of Climate change other than man and potentially more impactful? Wonder if there are other undiscovered causes of Climate change? And perhaps these causes could have more impact than man. Hmmm?
124393. thingadonta at 01:08 AM on 8 February 2010
        Could climate shifts be causing global warming?
        A quibble. "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" I don't see how this statement is logically valid. Just because A is sensitive to variability, doesn't mean B is sensitive to variability. 'Variability', whether internal or imposed, must include, by definition, non-variability (ie a subset of variability). Or, in other words, climate can be less sensitive to imposed forcings, because logically, such an effect comes under the definition of 'variable'. It's much like the self-contradictory statement 'everything is possible', which is of course self-contradictory because it would also mean that the impossible is possible.
124394. Riccardo at 22:13 PM on 7 February 2010
        Could climate shifts be causing global warming?
        Good and timely post; i bet we'll need point people here a lot in the near future. Indeed, my impression is that this is one of the hardest point to grasp, (multi) decadal cyclical variability, or climate shifts. I noticed a lot of interest in the scientific community on this topic and Trenberth's words, so grossly misinterpreted, every so often come to my mind, it's a travesty that we can not yet account for this variability.
124395. CBDunkerson at 21:41 PM on 7 February 2010
        Could climate shifts be causing global warming?
        It seems likely that there is some truth to both the sulfate and oceanic heat balance theories. Each has a clear impact on temperatures, but we don't really have sufficient data to determine the magnitudes. We're talking about pre-1970s after all. There were no satellites to measure the sulfate aerosol levels in the atmosphere or the severity of a particular oceanic oscillation... instead we've got estimates. Ditto for the impacts of even earlier volcanic and solar activity. Take different estimates of these factors and you get different results on which has driven temperature shifts over the past century. The article notes that when the Arctic is included the current 'cool' phase is not very pronounced at all. If you look back it can be seen that this actually fits another pattern in the data. Assuming these climate shifts run for about 30 years we can see (as reflected in figure 1); to 1910: Steep cooling to 1940: Steep warming to 1970: Moderate cooling to 2000: Steep warming to 2010: Essentially flat The magnitude of the cooling phases is decreasing... which is consistent with a relatively fixed amplitude up and down oscillation overlaid with an accelerating warming trend. Basically, if Tsonis and Swanson's findings are correct then it looks as if we have reached a point where we no longer have alternating 'warming and cooling' climate shifts, but rather 'warming and flat'... and logically in the next iteration it would vary between 'warming and less warming'. This is why we sometimes hear suggestions that warming could be 'on hold' for another two decades... based on the assumption of this playing out as a 30 year 'flat' phase. Of course, even if Tsonis and Swanson are correct, positive feedbacks which have passed a certain threshold (e.g. Arctic sea ice) could shift the balance and result in resumed warming even during this 'cool' phase.
124396. David Horton at 20:23 PM on 7 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        Ah, Charlie A. "By 2020, in some countries, yields from rain-fed agriculture could be reduced by up to 50%.". Mmmm, let's check out the logic of that statement shall we? I know you don't like to do the research yourself. OK "By 2020" - well that's ten years away. And since we know that agriculture in some countries (Australia is the one I am intimately equated with) is already under strain, and the forecast is for worsening conditions in the part of Australia (and therefore other similar countries, certainly in the southern hemisphere) that has the most agriculture, I suggest that 2020 as a date for big reductions in crops is not unreasonable. "Some countries" - see they are being very cautious here to avoid the "alarmist" stuff that the denierindustry loves to accuse them of. Just "some countries", not all, because circumstances will differ across Africa, "some countries". So what are you saying Charlie - you think NO African countries are going to have agriculture under threat in ten years? Hmmm, I have a house to mortgage if you want to bet your shirt on that. "Could be" - again, you see, cautious. I would say "will be" but then I've read a lot of literature and I'm living through the global warming of Australia on a farm. "Up to 50%" - enough caution already. But what do you think would be a fair figure Charlie - 10%, 20%, 30%, 40%? Well, I don't know, either, precisely, no one does, but those figures are all "up to 50%". You think none of them are right Charlie? "appears that there isn't any scientific backup for the rather dramatic conclusion" - you reckon Charlie? We've already seen that it isn't a "dramatic conclusion", in fact it's rather wimpy, really. But CSIRO and other agencies in Australia have undertaken studies here showing the real (and already developing) threats to agriculture in what was once one of the breadbaskets of the world. Threats so real that even our former prime minister, a notorious climate change denier, set in train 5 years ago an investigation to see whether Australian agriculture could be moved from the southern half of the continent, where it has flourished for 220 years, to the tropical north (it can't in any meaningful way). Southern Africa is in a similar geographical situation to Australia, and I'm betting science bodies there are making the same grim projections. My apologies for the lengthy response, I grow weary of this glib denialism ("So the 2020 date is probably messed up") that thinks nothing bad is going to happen, or indeed could happen, to this planet as a result of human activities. Try doing the literature search Charlie, it ain't that hard. Come back when you are ready to discuss things sensibly.
124397. Doug Bostrom at 18:02 PM on 7 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        Charlie A at 14:05 PM on 7 February, 2010 "I haven't done the literature search myself, but it appears that there isn't any scientific backup for the rather dramatic conclusion." Come now, you've shown you can do better that that! How "appears", if you've not looked the literature?
124398. angliss at 16:23 PM on 7 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        I don't know about the year being right, but the basic problem is quite real. Here's some papers about problems with food crops around the world The first one shows that the mean losses in protein content were 13.9%, 15.3%, 9.9%, and 9.8% for potatoes, barley, rice, and wheat respectively. That means that these four staple crops all got less nutritious as a result of higher CO2 concentrations (never mind drought) http://www3.interscience.wiley.com/journal/119416696/abstract The second paper shows that African staples cassava and sorghum didn’t technically become less nutritious and lose protein content, they did became poisonous as a result of higher CO2 and the crop yields plummeted – at less than double current CO2 concentrations, crop yield for cassava fell by 90%. http://www.biolsci.monash.edu.au/staff/gleadow/docs/gleadow-2009-cassava-online.pdf Another paper by the same group found that white clover, an important pasture food for domesticated animals, will become more poisonous at higher CO2 concentrations too. http://www.biolsci.monash.edu.au/staff/gleadow/docs/2009-clover-cg-co2.pdf And let's not forget that plants in general aren't going to grow as much as most current models expect, because there's not enough fixed nitrogen globally for plants to absorb even the percentage that GCMs are anticipating. Here's the original paper, followed by my blog about said paper http://www.agu.org/pubs/crossref/2009/2009GL041009.shtml http://www.scholarsandrogues.com/2010/02/02/climate-insufficient-nitrogen/ So the 2020 date is probably messed up. But the overall sentiment - that staple food crops will become scarce and/or less nutritious, leading to large parts of the world having food shortages - is right on.
124399. Charlie A at 14:05 PM on 7 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        Carrot eater says " .... authors of WG2 ..... lazy". Not just the WG2. Here's the latest blooper, which appeared in the synthesis report, and has been quoted by the IPCC Chair and UN Secretary General Ban: http://www.timesonline.co.uk/tol/news/environment/article7017907.ece "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." I haven't done the literature search myself, but it appears that there isn't any scientific backup for the rather dramatic conclusion.
124400. carrot eater at 13:00 PM on 7 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        Whoever the authors of WG2 were (the list doesn't have familiar names), some of them seem to have been rather lazy.

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