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Comments 118651 to 118700:

118651. PaulK at 17:47 PM on 27 May 2010
        There's no empirical evidence
        Doug, Looking back at my posts, my attack on the article in the Open Mind site was completely ill-founded, and I retract my comments unreservedly. I claim temporary insanity since I was in the grip of an obsession that led me to believe incorrectly that Riccardo was using the Open Mind article to support an invalid definition of the forcing term as used in the Schwartz model. The author's reputation for infallibility remains untarnished - at least by me.
118652. FerdiEgb at 17:38 PM on 27 May 2010
        Why Greenland's ice loss matters
        One need to take into account that the "accelerating" ice loss of Greenland's ice sheet is based on only a decade of accurate satellite measurements. But Greenland shows a quite different climate behaviour, compared to other parts of the world. In the period 1935-1950, the break-up point of the largest glacier was moving upward as fast as today and with a lot of ice loss at the ice sheet edges. After 1950, the glacier break-up point advanced again until the late 1990's. If one compares the summer temperatures around Greenland, these were higher in the previous period than today... See: http://www.ferdinand-engelbeen.be/klimaat/greenland_temp.html Some 6,000 years ago, the ocean north of Greenland was (at least in summer) ice free, due to higher temperatures (the Holocene optimum). Extrapolating a trend from a cyclic behaviour is quite triggy...
118653. ubrew12 at 17:26 PM on 27 May 2010
        Why Greenland's ice loss matters
        Comparing 2009's loss to the entire sheet is, perhaps, apples and oranges. Compare the 2009 loss to the loss needed to raise sea levels by 1m, which is 14% the size of the entire sheet. Then, project the loss from 2029 onto the same block diagram, to give a visual of the acceleration. Just a thought.
118654. Riccardo at 17:22 PM on 27 May 2010
        Has the greenhouse effect been falsified?
        Berényi Péter, you did it again. You used a descriptive graph and said that it's sylas that should provide more details. Even a superficial look at your graph in comment #56 should evidence that it's not worth any quantitative comparison with actual data. And indeed, of the three environments (out of the four spectra shown) two do not much your expectations, and for good reasons.
118655. Doug Bostrom at 16:23 PM on 27 May 2010
        There's no empirical evidence
        I'm not sure I see where the problem is regarding TOA imbalance, model versus observations (observed OLR vs. IPCC assumptions?). After cleaning up some obvious problems (>6W/m2, we'd cook more rapidly) with satellite measurements, we're left with direct imbalance observations of ~0.95W/m2 versus model predictions of ~0.85W/m2*. These rates are in reasonable agreement. I see PaulK's point w/regard to his formal look at the situation but something's not quite closing the circle; we can quibble about splicing etc. but it's pretty hard to simply say -all- OHC and atmospheric temperature measurements for the past 40 years are wrong and that temperature has not changed in that time, meanwhile both models and observations indicate an imbalance. Hmmm. A puzzle. *EARTH’S GLOBAL ENERGY BUDGET, K. E. Trenberth, J. T. Fasullo, J. Kiehl, Bull. Am. Meteorol. Soc. 90, 311 (2009) Full text here.
118656. Jeff Freymueller at 16:16 PM on 27 May 2010
        Greenland rising faster as ice loss accelerates
        #58 Humanity Rules, you can take solace in the model prediction if you like, but the present rate of mass loss rate of 300 Gt/year is about 300 km3/year of ice (1 km3 of ice masses about 0.9Gt), and by my count there remain 90 years of warming in the A1B scenario to go before we hit 2100. Meaning that the model is massively underpredicting the rate of ice loss. My guess is that the model ignores glacier flow, but that's a guess based on a quick look at Fettweis' web site, which shows figures for melting and precipitation. This may also provide some context for wes george's question about why this is a big deal (#51). I also got quite a chuckle out of someone's claim (I forget who) that Science and Nature were somehow competing to publish "alarmist data". You must be joking!
118657. Jeff Freymueller at 15:55 PM on 27 May 2010
        Greenland rising faster as ice loss accelerates
        #49 Humanity Rules, where did I say that the Earth as a whole was not losing ice over the last couple hundred years? I said GREENLAND was not. Now it is. That's a fundamental change. The blue diamonds on your figure may be the red squares on Figure 2 in John's original post. I prefer that other figure because it shows all of the independent estimates rather than a single source (and it lacks the overly squiggly "linear reconstruction", which is based on heaven knows what (not the observations!). Not to say that the general trend of that reconstruction is necessarily wrong, just that without a lot more information about how it was estimated, it shouldn't be assumed to be right, and its continuity is misleading.
118658. Ari Jokimäki at 15:50 PM on 27 May 2010
        Working out climate sensitivity from satellite measurements
        A recently published paper by Lin et al. addresses Spencer's feedback determinations. The end result seems to be that Spencer is studying noise. This paper is also relevant to Lindzen's stuff. By the way, here's my take on Lindzen & Choi (2009).
118659. Doug Bostrom at 14:37 PM on 27 May 2010
        There's no empirical evidence
        Apart from your semi-deplorable fling about "junk science" PaulK, may I just say how refreshing it is to see people such as you and Riccardo, "e" roll up their sleeves and invest some serious mental elbow grease here? There are only a few folks hanging out on the site who can have a conversation of this nature and produce reasonable repartee, particularly when it comes to doing maths; Riccardo, BP and a very few others come to mind. I'm not sure about the importance of the discrepancy you mention as a dilemma, I'm off to see what's up in the recent observational department on that but it's certainly pleasant to see such detailed treatment.
118660. HumanityRules at 14:14 PM on 27 May 2010
        Working out climate sensitivity from satellite measurements
        I read the (Chung et al 2010) paper. Could anybody tell me what climate sensitivity he reports from the satellite data. If you can convert it to oC I'd be grateful. This might be the relevant passage if that will help. "The recomputed slopes after removing the estimate of the Pinatubo radiative forcing (open circles in Figure 1d) are generally between 1.25‐2.0 W m−2 K−1 and more similar to the values of the AMIP model simulations." They also state "The computed values are consistently smaller than the value of the no‐feedback case (3.3 W m−2 K−1)"
118661. Philippe Chantreau at 12:58 PM on 27 May 2010
        Collective Intelligence and climate change
        HR, complete re-organization of the transport system is inevitable at some point. It's just a matter of doing it in a controlled way, rather then being forced to.
118662. PaulK at 11:19 AM on 27 May 2010
        There's no empirical evidence
        Riccardo, I promised a post proving that the general solution I offered in #55 is easily reconciled with Schwartz if one accepts his assumptions. Generalised heating model: dH/dt = Q(t) – E(t) = absorbed SW (flux) – Outgoing LW(flux) at TOA Assume that at time t = 0, the system is in steady-state equilibrium: Q(0) = E(0). Now, keeping everything else unchanged, consider a positive impulse forcing F1 = constant which results in a perturbation, f(t), of the OLR. We can write: OLR(t) = Q(0) + f(t) ; Q(t) = Q(0) = constant ; dH/dt = -f(t) At this stage, we don’t know what f(t) looks like, but we do know some things about it: • Minus f(t) is positive definite on the open interval (0,te), where te is the equilibrium time. (Otherwise the (constant impulse ) forcing would have to cause a net cooling at some stage in its effect). • As the system restabilises at the equilibrium time, te, f(t) must go to zero. • It is both closed and integrable, since the area bounded by the curve represents the finite energy commitment associated with the impulse forcing, F1. This system can be solved for the total perturbation (and hence for OLR) by superposition. This permits one to model combinations of input and output forcings over time. But let us consider the simple case first of where we have an exponential or annually geometric growth in CO2, translated into a forcing which is linear with time: F(t) = bt. The solution is analytic for this condition, but for convenience later, we will choose a superposition timestep of 1 year. We set the first year forcing F1 = b. All subsequent years are then also equal to F1 to satisfy F=bt. This is equivalent to superposing each year the same perturbation function f(t) to obtain the total perturbation to the system. The solution is then OLR(t) = Q(0) + integral of f(t) from 0 to t for all t< te OLR(t) = Q(0) + integral of f(t) from 0 to te (i.e. a constant) for all t>=te Note then that independently of the choice/calculation of the perturbation function (f(t)), OLR is monotonically decreasing until the equilibration time, and stays constant thereafter for this case of F(t) = bt which is proxy for a geometrically increasing CO2 concentration. This is an analytic result. So, does the above solution work for the Schwartz model? In Schwartz, the equilibration time strictly speaking is infinity (NOT tau). The perturbation function for a constant impulse forcing F1 in Schwartz is given by f(t) = -F1*exp(-t/tau) = -b*exp(-t/tau) Substituting into the generalised solution for OLR above, we obtain: OLR (t) = Q(0) + integral of f(t) from 0 to t = Q(0) + b*tau*(exp(-t/tau) – 1) for all t less than te = infinity. You should then find that this is compatible with the solution we obtained directly from manipulation of Schwartz. Next stage is to better understand the difficulties of reconciling the increasing OLR with IPCC assumptions.
118663. HumanityRules at 10:33 AM on 27 May 2010
        Greenland rising faster as ice loss accelerates
        Present and future climates of the Greenland ice sheet according to the IPCC AR4 models Bruno Franco1 , Xavier Fettweis, Michel Erpicum and Samuel Nicolay Climate Dynamics DOI 10.1007/s00382-010-0779-1 Abstract "......We also show that the GrIS surface mass balance anomalies from the SRES A1B scenario amount to −300 km3/year with respect to the 1970–1999 period, leading to a global sea-level rise of 5 cm by the end of the 21st century.........." 5cm would be less problematic.
118664. Doug Bostrom at 10:15 AM on 27 May 2010
        Working out climate sensitivity from satellite measurements
        Thingadonta needs to go back to school. Basics of general circulation models. Free to read, no need to speculate.
118665. chris at 10:11 AM on 27 May 2010
        Working out climate sensitivity from satellite measurements
        Berényi Péter at 09:02 AM on 27 May, 2010 "The paper is about short term water (vapor+cloud) feedback and they do find a low sensitivity here." No they don't Peter. I wonder whether you've read the paper. In a scientific paper your interpretations have to be consistent with the data you present and its analysis. In this case Spencer and Braswell fiddle around with various ways of plotting globally averaged anomalies in CERES net fluxes and find "considerable scatter". They try higher time resolution and find negative regression slopes (flux vs surface temperature) which they suggest cannot represent the real sensitivity. They try restricting the analysis to the global oceans (60 oN to 60 oS latitude) with daily resolution comparisons of flux with sea surface temperatures...however they find the correlations are negative. They try extending the time scales of intercomparisons (radiation flux and SST). They try phase space plotting of the data... Eventually they come up with "evidence of linear striations". These have slopes of around 6.2 W.m-2.K. Spencer and Braswell state: "These striations are significantly different from a similar plot of two time series of random numbers, shown in Fig. 3b, suggesting that the striations are due to some underlying physical process." Does that sound like they've "found low sensitivity here"? I don't think so. The paper has some interesting comparisons of a simplified model with GCM's. It's quite good at highlighting the difficulties of identifiying fast feedbacks in the presence of external forcinsg. What it doesn't present evidence of is "low sensitivity". Of course Spencer may say otherwise on his blog (a bad habit). But if you can't justify an interpretation in a scientific paper, then that interpretation is unlikely to be scientifically valid.
118666. Berényi Péter at 09:14 AM on 27 May 2010
        Working out climate sensitivity from satellite measurements
        #13 chris at 08:17 AM on 27 May, 2010 Incidentally, it's worth looking at Foster and Gregory 2006 The paper is available here.
118667. Riccardo at 09:11 AM on 27 May 2010
        Working out climate sensitivity from satellite measurements
        Chris G, did I say anything about the future? I just gave the "standard" definition of sensitivity which could in principle be used to evaluate it using past data. Maybe John's response to Alexandre #2 is clearer than mine.
118668. Berényi Péter at 09:02 AM on 27 May 2010
        Working out climate sensitivity from satellite measurements
        #11 chris at 07:41 AM on 27 May, 2010 he (and Braswell) are quite explicit in stating that the parameter they pulled out of their analysis doesn't have any necessary realtionship to the climate sensitivity as it is commonly understood Of course they state that as it is true. The paper is about short term water (vapor+cloud) feedback and they do find a low sensitivity here. There may be any number of feedbacks operating on longer timescales, some of them strong positive. However, current computational climate models can't project much warming with no fast & strong positive water feedback. Here is an earlier presentation by the same authors on this topic, 16 December 2009 AGU Meeting, San Francisco, CA
118669. Berényi Péter at 08:47 AM on 27 May 2010
        Estimating climate sensitivity from 3 million years ago
        FYI The Spencer & Braswell (2010) thing is continued here
118670. thingadonta at 08:44 AM on 27 May 2010
        Working out climate sensitivity from satellite measurements
        Firstly, I think the above discussion is very good. A few points: The global data is too imcomplete to make a definitive conclusion about climate sensitivity, especially in the higher latitudes. However, most of the data I have seen does suggest the tropics don't warm as fast as other regions when the earth warms (which also means Hurricanes and Cyclones shouldnt increase in frequency with warming, because of the lower T difference and greater stability between the tropics and temperate regions). The papers looking at Earths history sensitivity, some of which you have presented on this site (eg Little Ice Age), are not definitive for climate sensitivity either. They are generally models which insert C02 to explain longer term trends, and leave out other factors, such as clouds and changes to ocean currents. The reason they 'converge' is because they use essentially the same causal explanations. They are not really that 'independent' (eg many papers refer to each other to provide eg back up to uncertainties in the data, like using the same dataset for proxy temperatures). Essentially, the models use the same assumptions to come up with the same conclusions.
118671. jimmck at 08:18 AM on 27 May 2010
        Human CO2 is a tiny % of CO2 emissions
        You have referred me to "working out climate sensitivity by satilite measuements" as a response. While it is not conclusive on most points it is conclusive on the fact that no one has a handle on global sea temperatures. There seems to have been a concensus developed that average atmospheric temperatures have increased by 0.7C over the last century but there is none on average seawater temperatures. The reason I am interested is that on an holistic basis it seems that the solubility curve of CO2 would require the oceans to give up 4% of their CO2 for a 1.0C temperature increase. ie it would take a 0.03C increase in average seawater temperature from 2000 to 2010 to explain the 43Pg's/GT's increase of atmospheric carbon over that ten year period.
118672. chris at 08:17 AM on 27 May 2010
        Working out climate sensitivity from satellite measurements
        Berényi Péter at 07:38 AM on 27 May, 2010 if......if...... I suspect the fast feedbacks will be found not to be negative, Peter. All the dodgy attempts to winkle out something with the appearance of a negative feedback (flawed analyses by Spencer and Braswell, and by Chylek, and by Schwartz, and by Lindzen and Choi) have turned out to be scientifically deficient. In any case, there are a couple of obvious flaws to the notion that fast feedbacks are negative. The first of these relates to the numerous direct measurements of enhanced tropospheric humidity in response to atmospheric warming. It's very difficult to come to a conclusion that this (a) doesn't exist, and (b) isn't a positive feedback. The second is the observation that we've had around 0.8-0.9 oC of global warming since the mid-19th century. It's easy to calculate that a radiative forcing from the known enhanced [CO2] with zero feedbacks should give a warming at equilibrium of around 0.4 oC (see point (v) here). Since we know that we aren't yet near equlibrium with the current forcing, and that a substantial aerosol load has offset some of the warming from enhanced anthropogenic [CO2], and that solar variability has made no more than around 0.1 oC contribution to this warming, it seems very unlikely indeed that the feedbacks to [CO2]-induced primary atmospheric warming are not positive and substantial (one should also factor in contributions from black carbon and non-CO2 greenhouse gases). And that's without considering the abundant evidence from paleotemperature/[CO2] relationships that indicate a climate sensitivity near 3 oC of warming at equilibrium per doubling of atmospheric [CO2]. Incidentally, it's worth looking at Foster and Gregory 2006, which does a very good job of highlighting the issues associated with attempting to use direct measures of TOA radiation to estimate climate sensitivity..... Incidentally (b!) Spencer and Braswell certainly are not talking about Charney sensitivity. They state this explicitly in their paper (see my post just above and the link therein). Lindzen would like to "sell" the pretence that his analysis is about Charney sensitivity, but it turns out not be...
118673. Berényi Péter at 08:13 AM on 27 May 2010
        Has the greenhouse effect been falsified?
        #57 Riccardo at 00:18 AM on 27 May, 2010 You can determine the temperature of the photosphere in the 14-16 μm range (CO₂ stopband) comparing it to the blackbody radiation curves. As the atmosphere is absolutely opaque in this frequency range, it acts as a perfect black body here. As from photosphere height up it gets transparent fast, this black body radiation segment is seen above wit no attenuation. Approximate temperatures - Fig 8.3 a (Sahara Desert): 215 K (-58°C) Fig 8.3 b (Antarctic ice sheet): 197 K (-76°C) Fig 8.3 c (Tropical Western Pacific): 215 K (-58°C) Fig 8.3 d (Southern Iraq): 217 K (-56°C) Temperatures a & d are close to the respective tropopause temps. Temperature for b may be much colder than indicated for polar tropopause, but it must be during polar winter when tropopause drops to the surface. Temp c is warmer than expected, but troposphere temperature over the tropics is variable both in space and time (of day). Anyway, in that graph photosphere temperature in CO₂ stopband is the same over clear sky and thunderstorm anvil. Therefore it should be above tropopause.
118674. Chris G at 08:04 AM on 27 May 2010
        Working out climate sensitivity from satellite measurements
        Are Lindzen et al only talking about Charney sensitivity? I may have missed that; it sounded to me that their sensitivity estimates did not include caveats about assuming no ice surface area changes and no atmospheric composition changes, etc. OK, if you assume that there are only fast feedbacks and you can detect a reduction in the rate of energy flux, then you can make an educated guess as to where equilibrium will be reached. However, since they only used SST from 1985-1999, SSTs have changed a lot since then, the ice extent has change dramatically in the last decade, and the composition surely has not remained static, I don't see that these are realistic assumptions.
118675. chris at 07:41 AM on 27 May 2010
        Working out climate sensitivity from satellite measurements
        Berényi Péter at 07:05 AM on 27 May, 2010 No I think we'll find that Spencer hasn't found anything of the sort Peter. In any case he (and Braswell) are quite explicit in stating that the parameter they pulled out of their analysis doesn't have any necessary realtionship to the climate sensitivity as it is commonly understood (i.e. the Earth surface equuilibrium temperature response to a radiative forcing equivalent to a doubling of atmospheric [CO2]). I described this in some detail here. I'm surprised you're commenting on a paper that you haven't read...
118676. Berényi Péter at 07:38 AM on 27 May 2010
        Working out climate sensitivity from satellite measurements
        #9 Chris G at 07:15 AM on 27 May, 2010 If someone can explain how a current radiative imbalance can be used to predict the sum of future radiative imbalance, I'd be glad to hear it. We are talking about Charney sensitivity right now. Most of it is supposed to come from atmospheric water (vapor+cloud) feedback. As tropospheric H₂O turnover time is short (~9 days) and even for the stratosphere it is on the order of one month, it is a fast feedback. If it is found to be strong negative, all other longer term feedbacks can only operate on an already attenuated signal.
118677. Chris G at 07:15 AM on 27 May 2010
        Working out climate sensitivity from satellite measurements
        Riccardo, I don't think so. Measured in the long runs, energy-in equals energy-out. Whatever energy the earth receives is radiated off in time. This is true whether the earth is approximately stable in a snowball state or approximately stable in a hothouse state. A snowball state is possible when relatively more of the energy received is radiated back out at wavelengths more or less transparent to the atmosphere. A hothouse state occurs when there is relatively more of an asymmetry between wavelengths received and wavelengths emitted. An imbalance only tells you how much energy is being added or subtracted from the system at that time, or over the course of of whatever history you have. I don't think it can tell you what the future will bring. It can give you a good idea of the current rate of change, but since it doesn't tell you anything about the mechanics involved, I don't see that it can tell you if that rate will increase or decrease over time. The integral of the rate of change over time will absolutely tell you the total amount of change, but if you don't know anything about how long a rate of change will persist, you can't say anything about what the total change will be. Climate sensitivity generally refers to the amount of temperature change when a new point of equilibrium is reached. If someone can explain how a current radiative imbalance can be used to predict the sum of future radiative imbalance, I'd be glad to hear it. I kind of skimmed the article Barry linked. Two things struck me: Lindzen et al specifically state that they are aware of the shortcoming of only using tropic data; there's no need to hammer them on it. They apply a lot of linear tests for feedback effects while the historical proxy data indicate that they tend to be non-linear. I guess I still have the same basic problem with Lindzen that I've had for a while: If the climate sensitivity to forcings is so low, how did the climate change so much in the past?
118678. Berényi Péter at 07:05 AM on 27 May 2010
        Working out climate sensitivity from satellite measurements
        Another major flaw in Lindzen's analysis is that they attempt to calculate global climate sensitivity from tropical data. Roy Spencer has found Strong Negative Feedback from the Latest CERES Radiation Budget Measurements Over the Global Oceans between 60N and 60S. That covers 87% of the Earth's surface and almost all the ice free oceans. Spencer, R. W., and W. D. Braswell (2010), On the Diagnosis of Radiative Feedback in the Presence of Unknown Radiative Forcing J. Geophys. Res., doi:10.1029/2009JD013371, in press. (accepted 12 April 2010), paywalled.
118679. Riccardo at 05:30 AM on 27 May 2010
        Working out climate sensitivity from satellite measurements
        Alexandre, to evaluate climate sensitivity you need not know any specific forcing provided that you measure the total energy imbalance. Afterall, this is just (one of) the definition of climate sensitivity, the response to a energy imbalance.
118680. johnd at 04:56 AM on 27 May 2010
        Unprecedented Warming in Lake Tanganyika and its impact on humanity
        Pat Moffitt at 14:01 PM, I agree totally with you on the dangers of wrongly assigning blame, particularly in this instance, it is something that also applies to many other issues globally. I cannot help but wonder how much influence respected journals have when they perhaps unconsciously create a preconceived notion in their readers minds when studies such as this one with overlapping implications are titled for publication. Getting back to the matter of nutrients, I do acknowledge that it is a large body of water with an expected large reserve of nutrients. But even in oceans, rivers through the creation of suitable habitats such as deltas, and the delivery of nutrients, sustain rich fishing grounds that have become dependent on the inputs from the river and thus are subject to the conditions that control the inputs into the river system in areas remote from the fishery itself. These are only general observations and I don't have any knowledge specific to this lake such as the distribution and output of any fishings grounds or even if there are such areas within the lake, but I agree totally that the focus should not be allowed to be taken off the work that needs to be done, not only to further understand what is happening and why, but as you noted, to create some workable plan to sustain the lakes output into the future.
118681. barry1487 at 04:09 AM on 27 May 2010
        Working out climate sensitivity from satellite measurements
        I wonder what the climate sensitivity would be if Lindzen's method was applied to data from the Arctic circle.
118682. barry1487 at 03:24 AM on 27 May 2010
        Working out climate sensitivity from satellite measurements
        Alexandre,

        I understood Lindzen's paper is about figuring out the relationship between radiative forcing and temperature. How was CO2 included there?

        you can view the full version Lindzen et al 2009 here: http://www.drroyspencer.com/Lindzen-and-Choi-GRL-2009.pdf The brief mention of CO2 therein is much the same as here (example of energy imbalance from CO2 doubling).
118683. Ned at 03:11 AM on 27 May 2010
        Greenland rising faster as ice loss accelerates
        wes george writes: You guys realize that it is hard to get to excited about Greenland's icecap melting at 300gt annually out of 2.8 million gt, especially since that's got to be the high end of the estimate. GRACE estimates the melt at only 185gt annually. No, actually, GRACE shows that the loss of mass from Greenland has been accelerating, and is now over 300 GT/year. You really need to look at this quantitatively. Not many years ago, Greenland was actually neutral or gaining mass because warming was slight enough that the increased ablation was more than compensated for by precipitation. But the mass balance is now on a clearly accelerating downward trend. From a discussion in another recent thread: [O]ver the past decade the rate of ice loss from Greenland accelerated by about 11% per year. This is highly unlikely to continue (there would be no ice left by ~2075 or so). If that acceleration dropped to 3% per year tomorrow and continued for the rest of the century, you'd end up with 0.3 to 0.4 m sea level rise from Greenland, 1.0 m SLR total. One meter of sea level rise would be very problematic. But that's assuming a much lower rate of acceleration than we've seen over the past decade ... and Greenland would still have 93% of its ice. That's a pretty scary thought, IMHO.
118684. Doug Bostrom at 02:45 AM on 27 May 2010
        Greenland rising faster as ice loss accelerates
        Further to Phila's remarks on "alarmists", "warmists" and the like, this research was done and will continue to be done quite apart from any ideological considerations; folks such as Phil Jones are nice examples of somebody's curiosity leading them inadvertently into the limelight, as Pielke Sr. recently remarked. The muse researchers are following is mostly a private spirit. Public reactions to research findings are quite divorced from motivations leading to new discoveries; Charles Darwin did not set out to upset Christian orthodoxy regarding creation but inadvertently blundered into that controversy. The exact behavior of ice sheets, the response of the crust to changes in mass balance, all these matters and more will be scrutinized to a fare-thee-well not because researchers are grinding some axe but instead due to the human inclination to resolve mysteries. That may be a hard thing to believe but I think most scientists would largely agree.
118685. Phila at 02:33 AM on 27 May 2010
        Greenland rising faster as ice loss accelerates
        Wes, "Hard to imagine our hydrocarbon-based economy surviving the next 40 years of technological evolution." It was hard to imagine in 1970, too. And yet, here we are.
118686. chris at 02:33 AM on 27 May 2010
        Robust warming of the global upper ocean
        Ken Lambert at 23:46 PM on 26 May, 2010 "The mechanism of heat transfer to the oceans from the atmosphere has always been unconvincing." Nope. An unconvincing variety of "common sense" doesn't "trump" a century of understanding of the thermodynamics of radiative heat transfer! Remember that for each 10^22 joules of energy added to the top 700 metres of the oceans, this region of the ocean (top 700 metres) warms by ~ 0.01 oC [*]. Therefore year on year variation of upper ocean heat content is very difficult to measure and yearly averaged measures of ocean heat content have a considerable associated error (as is apparent in the error bars in the data in the figures in the top post). As with all measurements where yearly data points have large associated errors, longer term measures are more robust than short term measures. So it's possible that the calibration errors in ARGO floats haven't been completely eliminated and we aren't quite measuring the upper oceans reliably. It's also possible that some of the heat may be in regions of the oceans (greater depths) and partly escaped detection. it's also possible that for a short period there hasn't been a significant radiative imbalance (e.g. due to a particular coincidence of atmospheric effects), and so some of the heat wasn't missing at all (we'll get it as an "added chunk" as atmospheric fluctuations shift in the other direction). We have reasonable evidence that sea level rise slowed for a couple of years around 2006-2008, but that the longer term trend of sea level rise has pretty much caught up. The sea level rise in recent years can't be fully accounted for from knowledge of land ice melt, and efforts to "close the sea level budget" for these short periods require some thermal expansion (enhanced ocean heat) contribution [**]. So there are some interesting uncertainties to be resolved for this very short period of time. No doubt in the next few years these uncertainties will be resolved. However as with all areas of science, one doesn't choose one area of uncertainty, select a particular set of data, and then assume that encasing this within a bit of arithmetic defines absolutely what's happening in the natural world. ------------------------------- [*] In case anyone wants to check my sums: surface area of oceans: 3.61 x 10^14 m^2 volume of top 700 metres: 3.61 x 10^14 x 700 = 2.57 x 10^17 m^3 = 2.57 x 10^20 litres weight of this seawater: 2.57 x 10^20 x 1.03 kg (density correction) it requires 4186 joules to warm 1 kg of water by 1 oC raising the temperature of the top 700 metres of the oceans by 0.01 oC requires 2.56 x 10^20 x 4186 x 0.01 = 1.07 x 10^22 joules..... [**] recently reviewed here: A. Cazenave and W. Llovel (2009)Contemporary Sea Level Rise Annual Review of Marine Science 2, 145-173
118687. Doug Bostrom at 02:32 AM on 27 May 2010
        Robust warming of the global upper ocean
        Ken Lambert: The mechanism of heat transfer to the oceans from the atmosphere has always been unconvincing. You'll need to develop that assertion into an explanation better than what others practicing in the field have done before you're convincing. You do realize that, right?
118688. Doug Bostrom at 02:24 AM on 27 May 2010
        Greenland rising faster as ice loss accelerates
        Wes, read this to get up to reasonable speed on the whole subject: Spencer Weart's The Discovery of Global Warming. In particular your remarks about technological advances superseding the amount of C02 we've added to the air suggest a lack of sufficient background in the topic.
118689. Doug Bostrom at 02:17 AM on 27 May 2010
        Sea level rise is exaggerated
        Daniel you'd need to do some ferreting on your own to develop confidence in the idea but the time disparity in response you note is likely down to the fact that sea level rise is due not only to addition of water from melting ice but also significantly to thermal expansion of the sea itself. The world ocean has been quite efficiently absorbing "excess" retained heat and thus expanding in a noticeable way during the entire period in question while up here in the air the temperature has only more recently risen sufficiently to begin carving into terrestrial ice in a significant way, this in part because the ocean is indeed such a capacious sponge for warmth. There's a helpful primer on thermally-induced sea level rise here. There is an up-to-date and truly excellent discussion of sea level rise here* with a cornucopia of background information including some treatment of the lag of ice response versus ocean expansion. *Global sea level linked to global temperature Martin Vermeera, Stefan Rahmstorf 2009
118690. Phila at 02:11 AM on 27 May 2010
        Greenland rising faster as ice loss accelerates
        "Maybe they print this "alarmist" data because that is what all the data look like." Seems logical to me. And I'd take skeptics a bit more seriously if they'd give up their use of the term "alarmist." Either you have a valid scientific objection to the data, or you don't. If you don't, accusations of "alarmism" are meaningless. If you do, they're unnecessary.
118691. Michael Le Page at 01:53 AM on 27 May 2010
        Working out climate sensitivity from satellite measurements
        I think the page you link to on climate sensitivity could do with a little revising. It may be worth pointing out a) that most recent estimates of sensitivity based on past climate suggest it is rather more than the model consensus of around 3 C (eg Pagani 2009) b) that the reason for this is that models include only fast feedbacks ie Charney sensitivity
118692. PaulK at 01:50 AM on 27 May 2010
        There's no empirical evidence
        Riccardo, Well, erm, OK. I guess if my bank manager were to say he were going to repay only the interest instead of capital and interest, you could describe that as structurally identical. I think what you are saying is that you wrote "OLR" when you intended to write "Delta OLR", where you would/could define the latter as OLR(t)minus the radiative input or output prior to the forcing being imposed. I think you are also suggesting that in context, I should have been smart enough to figure out what you meant rather than what you wrote. In this, I think you are right. I should have spotted what you intended to say. However, by a remarkable non-coincidental coincidence, the expression you wrote for OLR actually corresponds to the radiative imbalance perturbation function for the boundary condition of constant TSI - the thing I was focused on in the first instance, and which I would like to return to. This really did throw me off. Given that we do now (I believe) have a common understanding of Schwartz, what I would like to do is to take the general solution I offered in #55 and demonstrate that (a)it works perfectly when applied to Schwartz if one accepts the same (restrictive) assumptions as Schwartz and (b) that it is a lot more versatile in its ability to accept realworld data in order to assess how OLR should be moving. Unfortunately, I don't have time immediately, but I will post on (a) as soon as I do.
118693. Chris G at 01:38 AM on 27 May 2010
        Working out climate sensitivity from satellite measurements
        Hmm. IDK, but it seems to me that a satellite history would be useful for observing radiative imbalance, which would be largely influenced by fast acting heat sinks, and to a lesser extent fast acting feedbacks. But how would you separate the two? Also, for instance, it takes a relatively short time to reduce floating ice and observe an albedo effect, but it could take centuries to see the albedo effects of ice sheet reductions. I don't know that it would be easy to ferret out the effects of feedbacks that could take centuries from the larger signals, especially when your record is short. I suspect the short record that is available is dominated by the heat sink signal of ocean heat content rising, plus, an arctic albedo change would be confused with an ocean heat content sink. Locations and timings aside, I can't see that the premise of Lindzen's work, that you can predict feedback effects from radiative imbalances, is sound.
118694. daniel at 01:35 AM on 27 May 2010
        Sea level rise is exaggerated
        I feel I am getting mixed messages from the AGW community. On one hand Sea level has been rising since the 1800's which is caused by anthropogenic emissions warming the planet. On the other hand melting rates for Arctic sea Ice and increases in the global mean temperature anomaly have only risen from "normal" or "naturally caused" levels since the mid 70's. Please clarify when exactly AGW was supposed to have had an effect or why these factors should be so vastly seperated in time.
118695. chris at 01:33 AM on 27 May 2010
        Greenland rising faster as ice loss accelerates
        HumanityRules at 12:18 PM on 26 May, 2010 HumanityRules at 12:45 PM on 26 May, 2010 There’s nothing particularly alarmist in the data on Greenland ice melt, but there’s no question that the prognosis is alarming. Obviously during the past 100’s and 1000’s of years sea levels have waxed and waned a little as long term temperature variations cause polar ice sheets to advance and retreat. However over the last 2000 years (where we have a reasonable handle on sea levels; [*]), the evidence indicates little net change in sea levels. So sea levels likely did rise above present levels (by of the order of 8-17 cm according to [**]) during the Medieval period, and were likely at a minimum (of perhaps 24-30 cm below current levels [**]) during the LIA. During Roman times sea levels were apparently similar to mid 20th century levels. Now it’s going to be all in one direction during the coming century (barring astonishing solar phenomena or massive volcanic activity, or a truly remarkable change in technologies for energy production or CO2 sequestration). It’s pretty well understood that the rate of sea level rise is roughly proportional to the temperature difference between some temperature at which polar ice variation is balanced, and the extant temperature [***]. So as the Earth temperature rises during the coming century the rate of sea level rise will very likely continue to increase. That’s the expectation of greatest likelihood. I would say that's pretty concerning… …but I don’t see how a straightforward consideration of the evidence is alarmist. [*] G. A. Milne et al. (2009) Identifying the causes of sea-level change Nature Geoscience 2, 471 - 478 abstract [**] A. Grinsted et al (2010) Reconstructing sea level from paleo and projected temperatures 200 to 2100 AD Clim. Dynam. 34, 461–472. abstract [***] S. Rahmstorf (2007) A Semi-Empirical Approach to Projecting Future Sea-Level Rise Science 315, 368 – 370 abstract [***] M. Vermeer and S. Rahmstorf (2009) Global sea level linked to global temperature PNAS 106, 21527-21532 abstract
118696. daniel at 01:18 AM on 27 May 2010
        It's a 1500 year cycle
        Can we trust that the ice core data is collected and interpereted correctly? Counting those fine lines using a variety of techniques and extrapolating climate way back into the past may sound straightforward to the average laymen but how much error is there in the graph? All it takes is a slight shift in the assigned timeline for one of the ice cores and viola the bipolar climate becomes global. Thanks for the video but you will need to present the graph with links to the source and a brief explanation of the methods and reliability of this data. :)
118697. wes george at 01:05 AM on 27 May 2010
        Greenland rising faster as ice loss accelerates
        You guys realize that it is hard to get to excited about Greenland's icecap melting at 300gt annually out of 2.8 million gt, especially since that's got to be the high end of the estimate. GRACE estimates the melt at only 185gt annually. It took 33 years to go from 0 to 300gt, at that rate accelerating technological evolution will have yield innovations both social and economically beyond our wildest dreams long before even 1.0% of Greenland's ice is lost. Hard to imagine our hydrocarbon-based economy surviving the next 40 years of technological evolution. If this is the signal of AGW, then just what part of it is catastrophic and unprecedented? "This is a big change, and it is a big deal." Why? Just what does 30 years warming trend really mean to the life cycle of 3 million gt icecap left over from the last ice age?
118698. Alexandre at 00:58 AM on 27 May 2010
        Working out climate sensitivity from satellite measurements
        I understood Lindzen's paper is about figuring out the relationship between radiative forcing and temperature. How was CO2 included there? How was sensitivity to CO2 calculated from periods of just a couple of years? Doesn't the Charney sensitivity have a multi-decade lag?
        Response: Climate sensitivity is about the climate's response to any energy imbalance. The definition refering to doubled CO2 is convention but it could just as easily say "climate sensitivity is the global temperature change caused by an energy imbalance of 3.7W/m2". So the key element of climate sensitivity is not how it responds to increased CO2 but how climate responds to warming. Eg - what feedbacks occur when temperature changes. This is the focus of Lindzen's and the other studies described above.
118699. ProfMandia at 00:54 AM on 27 May 2010
        Working out climate sensitivity from satellite measurements
        John, This is a very well done presentation and because it is short, to the point, and loaded with facts, it should be very effective. It appears that as more research gets published, climate sensitivity appears to converge on 3C with 2C being a very constrained lower bound. And, of course, 3C is not going to be pleasant at all (HUGE understatement). Scott A. Mandia, Professor of Physical Sciences Selden, NY Global Warming: Man or Myth? My Global Warming Blog Twitter: AGW_Prof "Global Warming Fact of the Day" Facebook Group
118700. Eric (skeptic) at 00:39 AM on 27 May 2010
        Satellites show no warming in the troposphere
        Re #15 suckfish, what matters is the distribution of the tropospheric warming. If it is concentrated then there will be more radiated heat and less retained. If it is diffuse then less radiated and more retained. The average increase or decrease doesn't tell us that and is not as important.

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