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jyyh at 16:24 PM on 30 May 2010On temperature and CO2 in the past
Great presentation. I see there's a more thinly dotted area in the domain occupied for 420000 years, at about a quarter down from the oval top. Would this be the transitional times between glacials and interglacials? -
jyyh at 14:52 PM on 30 May 2010Skeptical Science now a Nokia app
cool, now i need to update my phone. doug, lol, but this is a climate site, maybe somewhere else? -
Marcus at 13:46 PM on 30 May 2010Latest GRACE data on Greenland ice mass
Wes, the myth that you're repeating is this idea that-because it might have been warmer in one region of the world than global temperatures today-that this means we have nothing to worry about. There is evidence that Greenland was-at the *peak* of the MWP-as warm as temperatures are today (based on 18-O isotope levels in the ice), but this says nothing about the temperature in the rest of the Northern Hemisphere. What also needs to be remembered is that all the evidence suggests that the warm period that gave rise to the Greenland colony occurred over the space to more than 4 centuries-wheras the warming of the late 20th century has occurred in the space of barely 4 decades. Its highly probable that a more rapid *rate* of warming might have different impacts on Greenland's ice than all previous examples of relatively slow warming in the past. -
Doug Bostrom at 13:13 PM on 30 May 2010Skeptical Science now a Nokia app
Amazing how fragmented the phone market is. How about we start an OS flame war? Something we can all disagree on! -
mothincarnate at 11:18 AM on 30 May 2010Skeptical Science now a Nokia app
Awesome! I never actually checked up if you answered about my question regarding the Nokia app, but I'm happy to hear it's available. Thanks John! -
angliss at 10:54 AM on 30 May 2010Skeptical Science now a Nokia app
Palm Pre Plus app? Now that Palm is about to be part of HP and is on Verizon, AT&T, and Sprint? Pretty please? With your sweetener-of-choice on top? -
MikeCoombes at 10:03 AM on 30 May 2010Working out climate sensitivity from satellite measurements
I was wondering if it might be possible to estimate climate sensitivity from yearly temperature changes in each hemisphere. The forcing would be from the changes in the amount of sunlight, not CO2, but I understand that the sensitivity should be the same to at least first order. Also the heat transport from one hemisphere to the other should not be as great an effect as just using the tropics. There could also be interesting hemispheric differences because of the differing land to ocean ratios and the amount of surface snow affecting albedo. Am I totally off base? Thanks. -
owl905 at 09:56 AM on 30 May 2010Websites to monitor the Arctic Sea Ice
One more to add to the robust list. NPEO North Pole Environmental Observatory http://psc.apl.washington.edu/northpole/index.html Two automated observatories are placed, and tracked, pn the central Arctic ice-flow. Excellent meteorological support, and live pictures daily. -
Riccardo at 09:24 AM on 30 May 2010There's no empirical evidence
PaulK, maybe I didn't understand your notation. Is your f(t) the same as what people usually call F(t)−λΔT? In other words, did you include both the forcing and the response to the forcing into f(t) so that it's not not just f(t) but f(t,ΔT(t))? -
Riccardo at 09:00 AM on 30 May 2010On temperature and CO2 in the past
Jeff the data are from the Dome C but it does not change much. Definitely to compare those data with the global average there is an amplification factor to take into account. In a comment above I quoted the value of 2 from Masson-Delmotte 2010. It would translate to about 5-6 °C, not unthinkable but on the high end side of the accepted range. Anyway, I think that a quantitative prediction of the expected temperature rise from just these GHG data is a bit implausible. Masson-Delmotte and co-workers expanded the analysis beyond just GHG and found a climate sensitivity varying between 0.76 °C/Wm-2 for the period 400-800 Kyrs and 0.86 °C/Wm-2 for 0 400 Kyrs, both near the central IPCC estimate. What may be a cause of concern is its increase over time and over forcing (the parabola in fig. 3 here). -
PaulK at 08:39 AM on 30 May 2010There's no empirical evidence
Hi Riccardo, Your first paragraph (#91) raises a profound question, which I believe requires a separate post to deal with. Before I can get to it, however, your second paragraph suggests to me that we still have a gulf of understanding to bridge. You wrote: “But then you confuse the forcing with the OLR and never in you analysis does the net balance appear. Indeed you write dH/dt=-f(t); here f(t) should be the net energy (im)balance but then it cannot be equal to the OLR. You need to have both the forcing and the thermal radiation. I'd suggest to first write and solve the heat balance equation for ΔT (sorry if i keep using variations, why bother with the equilibrium values?). After that we can try to see who's that guy we call OLR.” Let me deal with this sentence by sentence to see if we can bridge the gap:- “You confuse forcing with OLR”. I don’t believe that I do anywhere. Can you be more specific about where this confusion occurs and I will try to address it. “...never in your analysis does the net imbalance occur. Indeed you write dH/dt= -f(t);...” The net imbalance IN FLUX is the basis for the analysis. I wrote dH/dt = Q(t) – E(t) = absorbed SW (flux) – Outgoing LW(flux) at TOA This IS the net imbalance at TOA. I also wrote:- 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) The net imbalance here is Q(t)-E(t), but Q(t) = Q(0) and E(t) after the forcing is equal to Q(0) + f(t). Hence the net imbalance is equal to Q(t)-E(t) = Q(0) – (Q(0)+f(t)) = -f(t). This is also by definition equal to the rate of change of energy entering or leaving the system, so we also have:- dH/dt = -f(t). “Here f(t) should be equal to the net energy imbalance.” No. It should not. The perturbation f(t) has the dimensions of FLUX. The negative form –f(t) is equal to the net FLUX imbalance for this boundary condition of constant input flux. This function represents a perturbation of OLR for a single pulse of CO2. It would have to be integrated w.r.t. time to give a net energy imbalance. “...but then it [f(t)] cannot be equal to the OLR. “ You are right. It is not equal to the OLR. It represents a perturbation of the OLR for a single impulse forcing . The OLR for this forcing (and a boundary condition of constant absorbed SW) = Q(0) +f(t) as stated. “You need to have both the forcing and the thermal radiation.” Agreed. They are both built into the perturbation. “I'd suggest to first write and solve the heat balance equation for ΔT.” Well as perhaps we will eventually get to, I am not sure what this should be in the real world. On the other hand if you want a solution for ΔT based on Schwartz-like assumptions, then you immediately have one from the solution I proposed by writing CdT/dt = C dΔT/dt = dH/dt. Since we know dH/dt, we can trivially calculate ΔT. This post is already too long, so I will answer the more difficult question that you posed in your first paragraph (Why use this new numerical solution when there is one already available?) in a separate post, when I get a little more time. But one thing which you said did strike me. I may be wrong, but I get the impression that you think I backed out the solution for OLR from Schwartz. I did not. I solved the superposition equation from the generalised definition, and then set all of the perturbations equal to each other for equal superposition timesteps. A “Chinese box” proof then demonstrates that the superposition solution is analytic for this boundary condition of F=bt. I then applied this solution to the more restrictive assumptions of Schwartz. It is possible that you are getting confused over the dimensionality of the solution I offered. Because the term for OLR involves an integral of flux, it may appear like there is confusion between energy and flux. There is no such confusion. The integral term is here effectively divided by time, but the superposition timestep equals 1 year. Hence the integral term here has the dimensionality of a flux. More later when I have a minute. -
johnd at 07:49 AM on 30 May 2010On temperature and CO2 in the past
Marcel Bökstedt at 20:57 PM regarding your comments on C reservoirs, particularly "Historically, the amount of carbon available in the atmosphere plus the carbon in the reservoir is a constant C', because at that time presumably no carbon was added to the system" Given that the amount of C that is released into the atmosphere through combustion of fossil fuels is relatively small compared to what is in constant exchange between the atmosphere and (1) the plants and soil and (2) the oceans, then very minor changes in the ratio of the exchange could be a significant factor in what is sequestered or released from the reservoirs being referred to. For the soil reservoir, plant growth is the key factor that apart from the obvious inputs, relies on C as the most basic foundation of them all, it being the energy source for soil biology and thus the most basic driver of all plant growth. Over the time spans examined in this discussion, CO2 levels have changed from plant starvation levels to still less than desirable levels of today. If the 6.5Gt of carbon being released annually by burning fossil fuels today is an important factor, than anything that has, or can vary the estimated 200Gt of C in constant exchange between the plants, soil and atmosphere today has to be allowed for. Are there any studies out there that estimate just how much C was being exchanged through biological means when CO2 levels were about 200ppm, because it is not enough just to measure what amounts of CO2 were present in the past, but to allow for the what all other changes it was causing when trying to make the connection with any of the other indicators also measured in order to close the loop. A very small change in any of the natural processes could have yielded greater changes than the simple combustion of fossil fuels today. -
Jeff Freymueller at 04:05 AM on 30 May 2010On temperature and CO2 in the past
Riccardo, the T anomaly for Figure 1 is the T anomaly for Lake Vostok, right? If that is correct, and if the temperature changes are amplified at high latitudes, might that not explain why the temperature changes globally are smaller? Present evidence suggests that the Arctic is warming ~3 times faster than global average, if that holds for the past data and for Antarctica then rather than 11C, the present CO2 might be predicted to raise global temps by 3-4C. Or am I wrong ahout the temp record used? -
shawnhet at 03:55 AM on 30 May 2010Working out climate sensitivity from satellite measurements
Chris, "ONE: However Spencer and Braswell state explicitly in their paper that their analysis doesn't have anything neccesarily to do with climate sensitivity at all. So you are basing your conjecture on a dismissal of S&B's assessment. Why do you consider that they are wrong?" I don't consider them wrong they aren't making the point that you are making. S&B (and I)are not talking about the long-term feedback response(ie climate sensitivity), they are talking about short-term feedback response. S&B doesn't *necessarily* say that long-term sensitivity must be negative because it doesn't measure that. However, for a given set of long-term feedbacks S&B predict a less sensitive climate than if short term variations are governed by noise(in S&B's terms). "THREE: You don't like my response to your question "What processes do you think governs the climate *on the timeframe* Spencer is dealing with?". I suspect that the reason is that you meant something other than what you asked. Clearly it's only noise and massive virtually instantaneous changes in forcing (volcanoes; extraterrestrial impacts) that can impact climate in such short timescales. I wonder if you really meant to ask "what processes do you think governs net TOA radiation transfer on the "timeframe" Spencer is dealing with"? If that's what you meant (please let me know) then I could answer that question. " In S&B's context clearly "noise" random perturbations in the relationship btw forcing and temperature. EArlier you quoted this from S&B "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.". FYI, the plot of random numbers would be noise per S&B. "FIVE: Another way of thinking of this is that the climate system has inertia to change and thus has a memory. Under the general case of persistent TOA radiative imbalance, the excess energy that accumulates in the climate system as a result of the imbalance isn’t radiated away. It’s only energy (positive or negative) that rises or falls above the energy compatible with the TOA forcing and climate inertia or “memory” that is rapidly dissipated, since the system will always tend towards the background state around which these internal fluctuations are “dancing”. Lin et al have just published a a couple of papers [**] in which they have taken Spencer and Braswell’s “striations” at face value, assigned S&B’s value to the coefficient f(s) and used this in a model that is more realistic than S&B’s by adding a term for the climate “memory”. When they do this, S&B’s purported value for what might be f(s) is entirely compatible with rather well-established estimates of the real climate sensitivity." Yes, Lin's approach is quite interesting. You'll note that they had to "add" something to make sense of what Spencer found. They did not call him names or try to say that everyone who disagreed with them did not "read the paper". No, they set out to actually try and explain the behavior of the real world. My brief reading of Lin's paper here doesn't allow me enough understanding of how the memory is supposed to work to comment much on it. i will read bit more and see what I think. Here it is for anyone who is interested. http://www.atmos-chem-phys.net/10/1923/2010/acp-10-1923-2010.pdf Cheers, :) -
Doug Bostrom at 03:26 AM on 30 May 2010Robust warming of the global upper ocean
PaulK, It seems we all share Trenberth's frustrations. Poor Trenberth has been scrutinizing this matter for decades now, always struggling with the sort of problems you detail. The thing I find most astonishing about his 2010 review are the enduringly paltry choices he has for obtaining primary data, choices that have problems known for 20 years or more and have gone largely unaddressed, or at least have not enjoyed concerted attention on the part of folks assembling mission objectives. We've ignored the requirement for better instrumentation, the price of which is vanishingly small compared to what we collectively spend on really important things, such as hair gel for us guys and eyeliner for the ladies. We can't just throw money into instrumentation randomly, but in fact we do have a reasonably good idea of what we want to measure. Venus has a dedicated climate orbiter on the way with the primary mission of taking a close look at various aspects of radiation there. Back here-- where we live-- we mostly use instruments glued onto orbiters as afterthoughts. As I mentioned earlier there are plans to intensify deep ocean measurements, good, but it's still a puzzle to me as to why we're -planning- data collection now as opposed to -analyzing- data we've already collected. Really, our thinking about money and opportunity costs is quite incoherent. -
Doug Bostrom at 03:12 AM on 30 May 2010Latest GRACE data on Greenland ice mass
Riccardo good point and how amazing that I can blather so around the target without mentioning it... -
mspelto at 02:18 AM on 30 May 2010Latest GRACE data on Greenland ice mass
Since the mass balance of a glacier is recorded on an annual basis, monthly or more frequent updates just do not make sense. Given the rapid snow melt off and well above average temperatures for Western Greenland this year, expect more losses. -
Riccardo at 01:48 AM on 30 May 2010On temperature and CO2 in the past
Thank you gallopingcamel. The understanding of current climate is like a puzzle, this post addresses just one piece, better, a tiny part of a piece. Although I may know what the final image will be I cannot tell from the tiny piece. I've been careful to avoid this trap which would cause the discussion to derail. -
Ken Lambert at 00:31 AM on 30 May 2010Robust warming of the global upper ocean
Doug #65 Chris #66 Similar information is repeated in Dr Trenberth's Aug09 paper: http://www.cgd.ucar.edu/cas/Trenberth/trenberth.papers/EnergyDiagnostics09final2.pdf which I have oft quoted in these blogs. The relevant Fig 4 of this paper shown how the TOA imbalance of 0.9W/sq.m is derived. Note that the main warming components are CO2, about 1.66W/sq.m and other GHG (1.0 W/sq.m) and the main cooling effects are surface, direct and cloud albedo. Solar is minimized at 0.12W/sq.m giving an overall net AG forcing imbalance of 1.6W/sq.m. Dr Trenberth then shows the Net Responses of the Earth system as -2.8W/sq.m (radiative feedback) and WV and ice albedo as +2.1W/sq.m giving a net response of -(minus)0.7W/sq.m. (The -2.8W/sq.m is calculated from S-B for a temperature rise of 0.75degC at a radiating temperature of 255degK. This is proportional to T^4.) The TOA imbalance is net AG (+1.6) and net response (-0.7) to give 0.9W/sq.m total net imbalance. Chris, the Solar forcing is only 0.12W/sq.m and we know that the 11 year cycle gives an incoming variation of about 0.25W/sq.m from top to bottom - therefore this is nowhere near enough to offset the postulated 0.9W/sq.m of net positive imbalance. If you look at the CERES satellite data there is a +6.4 W/sq.m TOA imbalance - which is impossible; so again we have an offset error and BP's low accuracy but high precision. In fact if you look at Doug's reference: http://content.imamu.edu.sa/Scholars/it/net/trenbert.pdf the absolute values of the components are all over the place - so only year to year differences make sense. If you go back to BP's post #30 or #36 (I think) he gives the last 10 years satellite chart and there are no significant year to year trends showing anything near negating the 0.9W/sq.m imbalance at TOA. Clouds and aerosols could be the most poorly understood, modelled and measured, however Dr Trenberth claims that HIRS is measuring to +/-1% which is +/-0.5W/sq.m and again - no big differences year to year. And of course the OHC seems flat since 2004 by Argo analysis. Conclusion: The 0.9W/sq.m imbalance might be much less over the last 6 years at least and the major culprits are Log CO2, Log 'other GHG', WV+Ice albedo feedbacks, or Surface, Direct and Cloud albedo. Clearly less warming, or more cooling or combinations of both. -
gallopingcamel at 00:09 AM on 30 May 2010On temperature and CO2 in the past
Congratulations Riccardo! I read your guest post several times but could not find any declaration that the CO2 concentration was driving the temperature changes over the Vostok timescales. Then I checked the comments and most of them referred to correlation rather than causation. Nothing for me to disagree with here. -
mlyle at 23:57 PM on 29 May 2010Latest GRACE data on Greenland ice mass
#15, Daisym, Land rise around Greenland (local relative sea level fall) will actually increase sea level rise at distant points. The land rise decreases the volume of the ocean. -
chris at 23:53 PM on 29 May 2010Working out climate sensitivity from satellite measurements
Thanks Riccardo....linking to that paper just wouldn't work for me! -
Riccardo at 23:50 PM on 29 May 2010Working out climate sensitivity from satellite measurements
BC, you need to use forcing instead of CO2 concentration. For example, between 1970 and today CO2 went from 325 ppm to 390 ppm. The forcing is F = 5.35*lnC2/c1 ~ 1 W/m^2; temperature increase has been about 0.5 °C and the sensitivity λ would be λ = 0.5/1 = 0.5 °C/Wm^-2. Double CO2 means 3.7 W/m^2 which translates to about 1.85 °C per doubling CO2, lower than the most probable value of 3 °C. -
Riccardo at 23:43 PM on 29 May 2010Working out climate sensitivity from satellite measurements
here's the link to Lin et al. 2010 paper cited by chris. -
chris at 23:32 PM on 29 May 2010Working out climate sensitivity from satellite measurements
shawnhet at 10:54 AM on 29 May, 2010 Shawnhet, I suspect you're doing what Spencer wants you to do - he's playing "fast and loose" with some numerological analyses of TOA radiation data and climate models and interpreting these (on his website, not in the paper) within an unrealistic simplified climate heat transfer model.....you're running with his insinuations with your extrapolated conjecture "If that relationship turns out to be robust, then the climate sensitivity will be less than, for instance, a system where the short-term response is governed by some other process." ONE: However Spencer and Braswell state explicitly in their paper that their analysis doesn't have anything neccesarily to do with climate sensitivity at all. So you are basing your conjecture on a dismissal of S&B's assessment. Why do you consider that they are wrong? TWO: This statement of yours is also incorrect: "It is pretty clear that they relate to coefficient of the short-term feedback process that seems to operate on changes in radiative forcing." Again it would help if you were to read the paper before making assumptions (even if Spencer does try to lead you to false interpretations). The "coefficient of the short term feedback process" [which I'll call f(s) for short a la Lin et al (2010) - see "FOUR:" and "FIVE:" below] isn't "operat(ing) on changes in radiative forcing". It's operating on changes in surface temperature (climate perturbations). THREE: You don't like my response to your question "What processes do you think governs the climate *on the timeframe* Spencer is dealing with?". I suspect that the reason is that you meant something other than what you asked. Clearly it's only noise and massive virtually instantaneous changes in forcing (volcanoes; extraterrestrial impacts) that can impact climate in such short timescales. I wonder if you really meant to ask "what processes do you think governs net TOA radiation transfer on the "timeframe" Spencer is dealing with"? If that's what you meant (please let me know) then I could answer that question. FOUR: Being careful with meaning is important in science. This is relevant to points TWO: and THREE: above. Let's take the situation that there is a change in sea surface temperature (SST) arising from an internal fluctuation in heat distribution (e.g. El Nino, so the SST temperature rises a bit). What happens to this excess heat? I would say that it will be radiated away, quite likely rather quickly. It's not going to be particularly affected by the radiative imbalance arising from the enhanced greenhouse effect. The latter sets the average background temperature which is the temperature that results from the greenhouse forcing and the particular state the the climate system has reached in response to the forcing at that particular time on its slowish trajectory towards a new climate equilibrium. So there's nothing really "opposing" the dissipation of the enhanced heat to space. On the very short term the climate system will always tend towards the state that the climate happens to be in, and so we aren't surprised if there's a very rapid dissipation of energy out of the system. That coefficient [f(s)] has got nothing whatsoever to do with the climate response to radiative forcing arising from a radiative imbalance at the top of the atmosphere (and to be fair to Spencer and Braswell, they say as much in their paper, even if you choose not to believe them). FIVE: Another way of thinking of this is that the climate system has inertia to change and thus has a memory. Under the general case of persistent TOA radiative imbalance, the excess energy that accumulates in the climate system as a result of the imbalance isn’t radiated away. It’s only energy (positive or negative) that rises or falls above the energy compatible with the TOA forcing and climate inertia or “memory” that is rapidly dissipated, since the system will always tend towards the background state around which these internal fluctuations are “dancing”. Lin et al have just published a a couple of papers [**] in which they have taken Spencer and Braswell’s “striations” at face value, assigned S&B’s value to the coefficient f(s) and used this in a model that is more realistic than S&B’s by adding a term for the climate “memory”. When they do this, S&B’s purported value for what might be f(s) is entirely compatible with rather well-established estimates of the real climate sensitivity. SIX: Apologies for the very long post (and I’ve answered the question I suspected you meant to ask anyway!). I might just add that once again the difficulties of estimating the true (Charney) climate sensitivity from contemporary real world measurements boil down to uncertainities of the true climate response times (inertia/memory etc.). Unfortunately, the system simply isn’t accessible to quick and easy answers…at least do far… [**] Lin, B. et al (2010) Can climate sensitivity be estimated from short-term relationships of top-of-atmosphere net radiation and surface temperature? J.Quant. Spec. Rad. Trans. in press (can’t seem to link to the abstract). -
BC at 23:08 PM on 29 May 2010Working out climate sensitivity from satellite measurements
Here's a novice question (I'll even accept Dunning Kruger question). If the the temperature is increasing by about .18C per decade driven by a CO2 increase of about 19 ppm per decade or roughly 5%, dividing one by the other gives a climate sensitivity of 3.4C. If the climate is not in equilibrium and is catching up then it becomes more than 3.4C. Another way to look at it is if the CO2 has increased over the last century by about 33% and the temperature by about 1C then the sensitivity is 3C. Again the equilibrium clause holds and it becomes more than 3C. What's wrong with this elementary analysis? -
Riccardo at 22:13 PM on 29 May 2010On temperature and CO2 in the past
Thank you chris for anticipating me, you correctly got my point and explained it probably better than i could do. Marcel Bökstedt, adding to what chris said, the mechanism you described is in all respect the feedback operating between T and CO2 which there's no reason to think it's not operating now. But this alone can not reasonably tell you what the future temperature will be, and infact i did not quote any in my post. But just to try the impossible, i'll do some rather crude speculations now. (Remember, I'm not a climatologist so I can try weird things). If the local sensitivity in Antarctica is about 4 °C/(Wm-2) when considering just CO2 and CH4, you may want to add the ice albedo feedback which amounts roughly to the same forcing as CO2 and CH4 combined. The local sensitivity would then be 2 °C/Wm-2. To make it global we can use a polar amplification factor of about 2 (Masson-Delmotte et al. 2010). So my impossible estimate of the global climate sensitivity would have been 1 °C/Wm-2. HumanityRules, I'm not sure of what you mean by particular analisys. The Mauna Loa and Law Dome data are shown just to point out that today we are out of the natural regime in place for the last 800 Kyrs. The outcome definitely requires more knowledge than just the T and CO2 paleo data. -
Marcel Bökstedt at 21:37 PM on 29 May 2010On temperature and CO2 in the past
chris> I absolutely agree with you on the antarctic amplification, thats why I stressed that T is the local temperature. By unreasonable simplification one could assume that the global temperature was determined by T in some simple way. I suppose that what I'm really worrying about is if this type of data give any real information about long term sensitivity. It seems to me that they sample data that are subject to a certain condition - no added carbon to the entire system - that simply isn't satified today. -
chris at 21:18 PM on 29 May 2010On temperature and CO2 in the past
Marcel Bökstedt at 20:57 PM on 29 May, 2010 "As Riccardo points out in a comment, the first thing you think when you see figure 2 is that this means that no matter what we do from now on, we will eventually get a temperature increase of at least 11 degrees." Actually Marcel, Riccardo pointed out that todays levels of [CO2] would (in the context of the ice core data), require temperatures of around 11 oC in Antarctica in order to arise naturally by temperature-induced recruitment of CO2 from ocean and terrestrial stores. The real point of the data and its presentation is that we are way outside the regime where [CO2] levels are a result of natural phenomenon (the balance between CO2 release and sequestration, and temperature). The data say's little about the Earth surface temperature that will result when the Earth comes to equilibrium with the forcing resulting from 392 ppm (current [CO2]). That requires an understanding of climate sensitivity. The likely values are still centred around 3 oC of surface warming per doubling of [CO2] (with the possibility of a little bit higher sensitivity if very long term feedbacks are included). A more general point. The temperatures/temperature anomalies in the Figures (including HR's figure in post 11) are temperatures from proxies within the Antarctic cores. Due to polar amplification, the globally averaged temperature anomalies during these periods were smaller. So the full ~ 8 oC of temperature variation (glacial-interglacial-glacial) of around 8 oC corresponds to a globally averaged temperature change of 5-6 oC... -
Marcel Bökstedt at 20:57 PM on 29 May 2010On temperature and CO2 in the past
Very interesting pictures. As Riccardo points out in a comment, the first thing you think when you see figure 2 is that this means that no matter what we do from now on, we will eventually get a temperature increase of at least 11 degrees. That's not good. But the situation is very complex, and a first look might be deceptive. There are many variables involved, and we are only keeping track of two - local temperature T and CO2 level C. Lets simplify and assume that local temperature is a good proxy for global temperature. There will be some the temperature forcings T' around (the one due to Mr. Milankovic and others). Then we have a suggested relationship between T and C. That is, we have a an equation f(C)=T, where f is an unknown function, which expresses approximately what temperature we would expect at a certain concentration of CO2. At the same time, we expect C and T to be largely determined by the forcing T', so that we actually have two functions T=t(T') and C=c(T'), related by the condition fc(T')=t(T'). Actually there are positive feedbacks between T and C. If one rises, so does the other. C can rise because there is a reservoir somewhere (in the oceans, in living stuff etc.) which contributes more CO2 to the atmosphere as the temperature goes up. Historically, the amount of carbon available in the atmosphere plus the carbon in the reservoir is a constant C', because at that time presumably no carbon was added to the system. Today we are changing C' by burning fossile coal. This means that at the same level of C, there will be more carbon left in the reservoir than before. It seems to me that this change of C' will change the feedbacks between T and C. But I don't know this for sure, correct me if I'm wrong! Maybe there is some sneaky way of constraining how these feedbacks depend on C'? So we would assume that today T and C depend on both T' and C'. We actually have T=t(C',T') and C=c(C',T'). If C' changes, we assume a new relation T=f(C',C), but I can't see how we can reconstruct the way T depends on C' from the paleo data, since C' didn't change before. There are no old data for varying levels of C'. The upshot seems to be that we don't really know if we will get the 11 degrees. From these pictures alone it could be 3 degrees or maybe 20. It depends on how the feedbacks between CO2 level and temperature react to an increase in the total amount of available carbon, and paleo data from the last half million years can't help us there. -
HumanityRules at 20:25 PM on 29 May 2010On temperature and CO2 in the past
"what I showed here is not a detailed analisys of any particular event" It seems to me this isn't exactly true because the past 100 years is given very particular analysis by the presence of the Law Dome and Mauna Loa data. So the data that stands outside the green ellipse is generated in a very different way to the rest. I thought it's worth posting the Vostok record. Hopefully this version is accurate.
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HumanityRules at 19:58 PM on 29 May 2010Websites to monitor the Arctic Sea Ice
10.John Cross Your pics would be great. -
Millennia at 19:25 PM on 29 May 2010Increasing CO2 has little to no effect
I'm confused; where is the backscatter represented in this NASA energy budget representation of Earth? http://eosweb.larc.nasa.gov/EDDOCS/images/Erb/components2.gif Further to that the whole greenhouse gas theory is based on erroneous assumptions of the Earth system acting as a black body. Incorrect application of the Stephan-Boltzman constant in this case means that the entire theory is based on a basic undergraduate error. NASA discovered this at the time of the Apollo moon landings, when they discovered their assumptions on Moon surface temperatures by day and night were out by up to 60K - because a black body is a THEORETICAL two dimensional surface, there is no such comparison either with the surface of a planet/moon or the 3 dimensional gaseous atmosphere that surrounds it.. Therefore the entire reason we don't freeze is down to the dynamics of the entire atmosphere that surrounds us, not to trace gases. The charge that the second law of thermodynamics is broken by postulating that heat moves from colder atmosphere to warmer surface has never been satisfactorily answered. NASA know this and put in in plain sight in their energy budget diagram, nothing in that allows for any change in composition of minor components of the atmosphere causing large changes in the planetary heat budget - an increase in heat content just increases the convection and radiation components to maintain balance. The complexity of the climate system is caused by the latent heat content of the oceans, which transfer heat in timescales of hundreds and thousands of years due to the massive difference in their heat capacity. And finally the whole system is dependent on the only external energy source, the Sun. It is that, plus the interaction with the oceans on a millennial scale, that controls our planet's climate. For us to pretend we can contol this system by tweaking one trace gas like a thermostat is arrogance of the highest magnitude -
Riccardo at 19:21 PM on 29 May 2010Latest GRACE data on Greenland ice mass
wes, a superficial look at the papers may be misleading. The IPCC does not consider ice sheet melting at all. The 50 cm by 2100 are then, explicitly, a lower bound. -
PaulK at 19:12 PM on 29 May 2010There's no empirical evidence
Hi Doug, Thanks for the kind words. Re your post #89, I am certainly not saying that the temperature and OHC measurements for the past 40 years are "wrong", although they do carry some hefty measurement uncertainties. We have undoubtedly seen planetary heating over a long timeframe. The key issue here, for me at least, is climate sensitivity and, ultimately, the cause and attribution of the heating. A careful reading of the Trenberth and Fusillo paper reveals that they do not claim anywhere that the satellite measurements of radiative imbalance match the climate models. On the contrary, they state that they do NOT, and then use the error statistics on the satellite measurements to show that the satellite data can be adjusted within the error bars so that it is “not incompatible with” the residual imbalance inferred from climate models. This however then leaves Trenberth’s question of where the missing heat energy was going in the period from around 2002 to 2008, when OHC showed a flat/cooling trend (Willis, Levitus, Cazenave). For me the jury is still out on OHC from the Schuckman paper, which is not only an outlier relative to the three papers I mention, and has not been reconciled to the shallower data, but would also mean that all previous reconciliations of energy balance (which did not account for Schuckman’s variation in deep ocean heat content) were fundamentally flawed. But back on topic, in practical terms the relative error statistics on the radiative imbalance from satellite measurements are very large (error analysis on the difference between two large numbers always reveals poor statistics); the measurement noise on the difference turns out to be almost an order of magnitude greater than the signal we are interested in! On the other hand satellite measurements for OLR can be quite PRECISE, but INACCURATE in absolute terms. This implies that the relative errors on trends in the measurements should be smaller than the error in absolute magnitude of the measurement, and very much smaller than the (even larger) relative error in the difference between the measurements. It is quite possible - likely even - that we can then deduce more from the trends in individual measurements than we can from the absolute differences between those measurements. So, is it important if a climate model (from a simple analytic model to a CGCM) doesn’t match the observed trends in OLR? Well, it obviously depends on what information one is trying to abstract from the model. But if one is talking about attribution studies, I happen to believe that it is crucially important. -
Doug Bostrom at 18:27 PM on 29 May 2010Latest GRACE data on Greenland ice mass
Wes, on a general note it's helpful to remember that IPCC is conservative in its assessments and of course all research cited in the IPCC 2007 reports is a minimum of 4 years old at this point. More recent research in fact indicates an acceleration of the wasting process in Greenland. That's why what you see reported on sites such as SkS may appear different than the 4th IPCC assessment. As an exercise, you might compare the 3rd report w/the 4th. -
wes george at 18:18 PM on 29 May 2010Latest GRACE data on Greenland ice mass
"The latest research indicates roughly 1 to 2 metres sea level rise by 2100 ..." Well, I guess that's more likely than a total melt by 2065 for a 7 metre rise, something that was once suggested here as an admittedly remote possibility once. Still, the IPCC models projected for even the worst possible scenario shows less than 50cm sea level rise by 2100 and only 100cm rise by 2200 and that's the worst case scenario...perhaps more likely 20 to 30cm by 2100. Big margin there. 2 metre rise scenario isn't until 2330 or so. So, I guess your interpretation of the latest data disagrees with the IPCC worst possible scenario by a factor of 2 to 4? http://www.grida.no/publications/other/ipcc%5Ftar/?src=/climate/ipcc_tar/wg1/fig11-16.htm -
wes george at 18:00 PM on 29 May 2010Latest GRACE data on Greenland ice mass
Marcus, Unfounded myth? There are Viking graves that are still permafrost today. The graves weren't dug in permafrost. [Let's stay in the correct hemisphere for this topic.] -
RSVP at 17:50 PM on 29 May 2010On temperature and CO2 in the past
Riccardo, Very interesting. The top two graphs are quite telling. The first suggesting CO2 increases with warming, while the second clearly indicates a deviation from this natural locus due to man's excessive fossil fuel combustion. -
Doug Bostrom at 17:27 PM on 29 May 2010On temperature and CO2 in the past
Figure 2 is a pretty stunning visualization. "Thought provoking", as Ned understates. Thank you, Riccardo. -
Riccardo at 16:36 PM on 29 May 2010On temperature and CO2 in the past
Ned, you made my feelings explicit, thanks. Marcus, I was talking about geologists and, you know, they use a very slow clocks and would call instantaneous something that happens in a few thousand years. :) -
johnd at 14:27 PM on 29 May 2010Working out climate sensitivity from satellite measurements
scaddenp at 13:33 PM, what on earth causes you to jump to that conclusion??? Read all the relevant posts. -
scaddenp at 13:33 PM on 29 May 2010Working out climate sensitivity from satellite measurements
Johnd - what on earth gives you the idea that clouds are left out of the process in climate model? See chp8 for instance in IPCC WG1, (for instance fig 8.14 and associated text). You should also note the improvement of cloud uncertainties between TAR and AR4 models. -
Marcus at 13:28 PM on 29 May 2010Latest GRACE data on Greenland ice mass
Wes George, I do wish people would stop repeating unfounded myths as fact. First of all: Like today, Greenland during the MWP has always been an extremely marginal region for human settlement. I've seen nothing in historical records or paleoclimatic data to suggest that Greenland has *ever* been warmer-during the last 12,000 years-than it is today. The name Greenland was just an attempt by Eric the Red to encourage colonists to move there-it was not supposed to be an honest indication of what the place was like (though it did, & still does, get quite green around the coast during Summer). As to the claims of temperatures more than 1-3 degrees warmer than today I say-cite your source! I've looked at numerous reconstructions, dating back as far as the end of the last glacial period, & the only time period that was apparently warmer than today was the so-called Climatic Optimum-around 12,000 to 8,000 years BP. Temperatures then were around 0.3 to 0.4 degrees warmer than the 20th C average (depending on which reconstruction you look at), but occurred over a period of *centuries*, not decades as is occurring now. Maybe the Mediterranean region was 3 degrees warmer during the Minoan period, than the *global* average today-but that's a purely *local* phenomenon & has no bearing on what global temperatures were like at that time (indeed, IIRC, much of North America & Northern Europe was very cold at this point in history-due to a slowdown in the Gulf Stream). -
Jeff Freymueller at 13:15 PM on 29 May 2010Why Greenland's ice loss matters
#57, that's OK, Ned. You reminded me that I need to look up that paper, and your explanation was fine! -
Jeff Freymueller at 13:11 PM on 29 May 2010Why Greenland's ice loss matters
#49 Chris G, the coast is uplifting quite rapidly today, although that is also very close to where the ice is being lost right now. If/when the main area of ice loss shifts to the interior, the uplift will be highest there but still probably faster than sea level rise at the coast. -
Jeff Freymueller at 13:08 PM on 29 May 2010Latest GRACE data on Greenland ice mass
#15 daisym, Greenland will rise faster than sea level rise if it continues to lose mass rapidly. This is currently happening in Alaska and Patagonia, where uplift due to rapid ice loss is several times faster than sea level rise. However, outside of the areas that are losing ice, land level won't change much and most of the world will just experience sea level rise. -
Marcus at 12:39 PM on 29 May 2010On temperature and CO2 in the past
Hm, I sometimes have problems with the definition of a "Wild Swing" in temperature. Having looked at the Vostok Ice Cores extensively, we're seeing a delta T of 10 to 12 degrees C-which is very large-but over a space of 25 to 50 kyrs. To put that into a modern-day perspective, its an average rise of about +0.005 degrees per decade. The modern day warming has been at a rate of +0.1 degrees per decade! -
Ned at 12:06 PM on 29 May 2010On temperature and CO2 in the past
Hey, Riccardo, thanks for a really neat post. Fig 2 and Fig 3 are really thought-provoking. Chris, your comments are as always very informative. -
Ned at 12:03 PM on 29 May 2010Why Greenland's ice loss matters
Our esteemed host, John Cook, writes: Response: While you're at it, check out my blog post on this paper :-) Ooh, now I'm covered in embarrassment. I should have known John would have done a post about that paper (and I should have used the Search box to find it!) By all means, do check out John's blog post about the components of the mass balance budget for Greenland. He shows the exact same figures I put in the comment above, but he explains them better!
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