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Tom Curtis at 03:52 AM on 15 May 2013The last time carbon dioxide concentrations were around 400ppm: a snapshot from Arctic Siberia
Saadi Aubydi @3, of topic, but the short answer is that N2 and O2 are not greenhouse gases because there is no charge imbalance between the two components of the molecule. That renders the gases transparent to IR radiation. Carbon Monoxide (CO) is a weak greenhouse gas because, although it does have a charge imbalance, because it only has two molecules it is limited in the sort of vibrations it can perform, meaning it does not absorb IR radiation at the main frequencies of emission within the Earth's atmosphere. This is explained in more detail here.
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Tom Curtis at 03:45 AM on 15 May 2013The last time carbon dioxide concentrations were around 400ppm: a snapshot from Arctic Siberia
HJones @2, the following are CO2 concentrations as measured by an aircraft in Colorado in 2004:
You will notice that while the measurements above 500 meters consistently record CO2 concentrations around 375 ppmv, those below that altitude are very variable, and much larger. That is because the CO2 concentrations below 500 meters are contaminated by local sources of CO2 (mostly forests), whereas above 500 meters the CO2 from local sources has become diluted, leaving the local concentration at the background level.
This is the problem with Beck's measurements. While accurate, they are also contaminated by local sources of emissions. Beck lumps all the measurements together without regard to whether they were taken in enclosed rooms (which can have CO2 concentrations up to 1000 ppmv with poor ventilation), in industrial cities, or in forests (which absorb CO2 in the day time, but emit it at night). He also does not distinguish between CO2 measurements in autumn (when decaying vegetation elevates local CO2 concentrations) or spring (when new growth depresses it). Because he simply ignores these relevant and well known facts, Beck's paper is propoganda, not science.
In contrast, the Mauna Loa measurements are taken at altitude away from industrial sites and forests, and only when the prevailing winds prevent contamination from the local volcano. They agree with measurements taken from many other remote sites including the South Pole.
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KR at 03:32 AM on 15 May 2013The last time carbon dioxide concentrations were around 400ppm: a snapshot from Arctic Siberia
HJones - See the replies to Becks paper by Keeling and Meijer. Short answer: Beck made measurements at ground level, seriously contaminated by local effects, whereas the Mauna Loa (proper spelling!), Antarctic, mid-ocean, and other measures are a far more accurate background measure with care taken to avoid industrial influences. Becks methods were inappropriate, and his measurements are accordingly of little worth WRT global CO2 levels.
I suggest looking at the more accurate and widespread CO2 measures than Beck's work - it's a brief video, well worth watching.
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Saadi Aubydi at 03:31 AM on 15 May 2013The last time carbon dioxide concentrations were around 400ppm: a snapshot from Arctic Siberia
Hi, Why CO2 is a greenhouse gas while CO and N2 are not?
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HJones at 03:15 AM on 15 May 2013The last time carbon dioxide concentrations were around 400ppm: a snapshot from Arctic Siberia
The above link shows other values for CO2 concentrations beside Mona Lau. When did the measurements in Hawaii become the standard? Are these others even valid?
Moderator Response:[RH] Fixed link that was breaking page format.
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John Hartz at 03:04 AM on 15 May 2013The last time carbon dioxide concentrations were around 400ppm: a snapshot from Arctic Siberia
John Mason:
Kudos on an excellent article combining a very well written text with outstanding graphics.
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Alex in the Farmbelt at 02:06 AM on 15 May 2013Leave It in the Ground, Climate Activists Demand
I would postulate most of the carbon cycle carbon that we consume comes to us with the help of fossil fuel carbon, so it is not a zero-sum game. Tractors, irrigation motors, trucks to transport use fossil fuels and even elements of fertilizers and pesticides come from petroleum. I don't know of an electric vehicle capable of performing the work necessary to grow & distribute enough food for the masses, regardless of the source of charge. Is there a solution to nutritional needs on a scale to satisfy 7 Billion people that does not involve petroleum?
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R. Gates at 00:21 AM on 15 May 2013Another Piece of the Global Warming Puzzle - More Efficient Ocean Heat Uptake
John Brooks,
I do not question that heat can be be advected to depths by downwelling, for certainly it can, I simply question the overall thermodynamic perspective given that the net flow of energy is always from ocean to atmosphere on a global basis. It seems more accurate to say the oceans are releasing less rather than taking up more, which is exactly the case during La Niña and cool phase PDO. In this regard, SST's are most instructive as they tell us more about heat being transferred from ocean to troposphere rather than about how much energy the ocean is storing. During the big El Niño of 1997-98, SST's were quite high, and of course that was a good indication that energy was leaving the ocean and we saw tropospheric temps rise and ocean heat content took a dive.
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Kevin C at 23:57 PM on 14 May 2013The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.
Bart: No, it's the 2-box model of Rypdal 2012 with an extra ENSO term - the response function is determined by fitting the forced response to the data. However the forced response is similar on the decadal level to the temperatures obtained by Hansen 2011 using the Green's function mode. The only difference is that he uses the model to get the response function.
Tamino writes about his version here.
You can actually get a marginally better AIC using 1.5 boxes (1-box + transient). -
KR at 23:54 PM on 14 May 2013The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.
Dr. Tung - If you are including the aerosol forcings and their changes over time, the sum forcings are again not linear since 1910, as per the figure in my post above. Note that not only tropospheric but stratospheric aerosols are involved in the "S" curve seen in 20th century forcing data. There is simply no support for a linear forcing during the 20th century, a requirement for your claim of a linear warming since 1910.
As per Kevin Cs comment, and your claim that "no CMIP3 or CMIP5 models have successfully simulated the observed multidecadal variability in the 20th century using forced response", I would simply point out Figure 9.5 from the IPCC AR4 report:
Figure 9.5. Comparison between global mean surface temperature anomalies (°C) from observations (black) and AOGCM simulations forced with (a) both anthropogenic and natural forcings and (b) natural forcings only...
Note that the models using all forcings match multi-decadal temperature variations quite well, including a mid-century pause. I fail to see significant support for your statement.
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Bart Verheggen at 23:43 PM on 14 May 2013The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.
Kevin, impressive comparison. Is there some more info somewhere on the ins and outs of the model and analyses used? In particular, is it using the Green's function of GISS model-E?
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John Brookes at 23:08 PM on 14 May 2013Another Piece of the Global Warming Puzzle - More Efficient Ocean Heat Uptake
Thanks R. Gates. I had not thought of the energy flow being from the ocean to the atmosphere before, but its rather obvious now that you mention it.
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Kevin C at 22:20 PM on 14 May 2013The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.
I think KR's comments on use of all the forcings is critical. In particular, I think that this key comment from your article is overstated:
It is fair to conclude that no CMIP3 or CMIP5 models have successfully simulated the observed multidecadal variability in the 20th century using forced response.
In fact, Hansen's model at least comes very close if you take into account internal variability in the for of El Nino. I haven't looked at the others, but here is a result from a simple 2-box model illustrating this fact:
This trivially simple model is available here for you to play with - for the figure above, just click 'Calculate'.
The key to this model is that it takes into account both forced response and ENSO. If you leave out the ENSO term (figure 5 on that page), then the model appears to fail to reproduce the mid-century cooling. When including it (figure 1) the model fit is extremely good except for 2 spikes either side of WWII. The temperature record is GISTEMP and so is missing the post-war SST adjustments, which probably accounts for much of the remaining discrepancy.
The significance of the ENSO term is that the trend in MEI on the period 1940-1960 is about 70% of the trend on 1997-2013. ENSO plays a significant role in the cooling on that period, and of course only corresponds to a single realisation of climate variablility. Using an ensemble of runs or alternatively using a simple energy balance model allows us to eliminate the internal variability. Imposing the real ENSO contribution allows us to figure in the actual realisation. The resulting model fits 92% of the variance in the data. You can test the skill by omitting different periods from the model fit.
We could redo the calculation with Hansen's data instead of the 2-box model, but the results will be similar. Ideally we'd use a longer time frame too. BEST should be significantly better than CET, and the Potsdam forcing data goes back to 1800 (although I think it omits the 2nd AIE). I'm afraid I haven't had a change to do this calculation yet.
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R. Gates at 21:48 PM on 14 May 2013Another Piece of the Global Warming Puzzle - More Efficient Ocean Heat Uptake
Rob,
Thanks for that explanation in repsonse to my post @2. It sounds plausible, but what bothers me is that the Pacific basin has not shown especially high ocean heat content increases, but rather it has been the Atlantic and Indian Ocean.
Also, @3 you said,
"There is the worrying possibility that 3 variables may have acted to slow surface warming during that time; the negative phase of the PDO, industrial sulfate pollution, and increased sulfates from increased volcanism of tropical volcanoes. Let's hope that that wasn't the case - it would imply significant surface warming when these 3 are no longer holding back greenhouse gas warming."
i think this could unfortunately be exactly the case, but I also would not discount a slight downward nudge from our rather sleepy sun during that time as well-- meaning that could even be a fourth factor. We had some very low total solar irradiance, and of course a current solar cycle that is the weakest in a century.
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Rob Painting at 21:38 PM on 14 May 20132013 SkS Weekly Digest #19
Seahuck - Not a good piece by Gillis. Relatively easy adaptation to climate change is simply a fantasy. Last time I checked, ocean acidification is still happening, and coral reefs the world over are in dramatic decline. Once the reefs and productive fisheries collapse (which they are on course to), I don't expect adaptation will be an apt description of what follows.
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Tom Curtis at 19:16 PM on 14 May 2013The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.
KK Tung @16, here are the 10, 15 and 20 year running means of the CET from 1660 to 2012:
As you can see, there is no consistent 50-80 year oscilation in the data. There is what might be a large amplitude 80 year oscillation from 1660-1740. However, the trough of that "cycle" corresponds with the Maunder Minimum and a large number of large volcanic erruptions, while the peak corresponds to a period without significant volcanic activity. In other words, that "oscillation" is more likely a result of forcing than not. Then from 1740 to 1910 there are seven distinct peaks indicating average "cycle" lengths of 25 years, although the cycles vary in both magnitude and length. The longest cycle length (treating the smallest peak as an aberration) is less than fifty years in length. Finally, from 1910 to 2012 you may have two cycles of 50 plus years. There is certainly no consistent periodicity over the entire period.
Tellingly, this pattern (or lack of it) shows up in your supplementary material, and specifically in figure S2:
Clearly the 50-90 year signal is almost entirely absent from about 1750 to about 1910. In contrast, during that period there is a strong 32 to 50 year signal. There is simply no compelling reason to consider the 50-90 year bandwidth a representing a physically important process while relegating the 32-50 year signal to irrelevance; and if we allow ourselve so broad a target as an oscillation that varies by a factor of 2-3 in amplitude and by more than a factor of 3 in period, it becomes almost impossible to not find your AMO in any random data.
Speaking of which, you claim a statistically significant 50-80 year AMO over the full length of the the CET record based on a wavelet analysis. Tamino has some very interesting comments on such analyses. Specifically, standard significance tests applied to wavelet analysis will overstate the statistical significance of observed oscillations because they do not allow for the fact that we are searching a large range of hypotheses simultaneously. To the extent that you have not compensated for that, therefore, your wavelet analysis will also overstate the statistical significance of the "detected" AMO signal.
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Bart Verheggen at 19:00 PM on 14 May 2013The anthropogenic global warming rate: Is it steady for the last 100 years?
Another approach would be to rather than using a questionnnable (see my previous commment) estimate of the AMO as a predictor in the regression analysis, see if there is a AMO-type (or other cyclical) signal is left over in the adjkusted temperature, after having corrected for the better known influences (solar, ENSO, volcanic, anthropogenic).
The Lean and Rind analyses would make me think there would not be a substial influence of such cyclical behavior, but that's worth investigating with newer data.
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Bart Verheggen at 18:51 PM on 14 May 2013The anthropogenic global warming rate: Is it steady for the last 100 years?
Thank you Dr Tung for engaging here about your paper.
It is an interesting analysis, but the results are strongly dependent on the assumed shape of the anthropogenic signal. This signal is not properly approximated as linear from 1850 onwards (see e.g. fig 8.18 of the AR5 SOD or similar figures). This is in contrast to the past three decades as analyzed by Foster and Rahmstorf, where the linear approximation is much more valid.By assuming linearity, the non-linear part of the anthropogenic forcing will be incorrectly attributed to the AMO.
See also this attempt to reproduce the results in the paper, but then using the time evolution of CO2 concentrations instead of a linear trend as a proxy for the anthropogenic forcing: http://www.staatvanhetklimaat.nl/2012/10/26/is-the-amo-the-explanation-for-the-1940-1970-temperature-standstill/
Obviously, this is still a very incomplete analysis, since the net anthropogenic forcing is not properly represented by the CO2 concentration (because of the logarithmic relationship and because of other forcings being also important), but it shows the strong dependence of the results on what is assumed to be the anthropogenic signal. The anthropogenic warming trend is seen to accelerate with this slightly better (though still flawed) assumption.
An improved (and very interesting) analysis would take the net anthropogenic forcing as the anthropogenic signal. If the AMO index can be properly detrended for such an analysis is questionnnable: All other tempoerature influences would have to be subtracted, and those temperature influences are actually what one is after with such an analysis. The detrending thus invariably involves either dubious or highly uncertain assumptions or circulair reasoning. The latter could perhaps be ameliorated by an iterative analyis.
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Tom Curtis at 17:12 PM on 14 May 2013It's too hard
yocta @26:
1) Bartlett's equation excludes an important variable, I, or the Emissions Intensity of production. Total emissions are equal to Population times per capita production times the emissions for a given level of production (P x A x I). Given suitable changes in these values, the product can fall even though some values continue to rise. In particular, if I falls towards zero, P x A can increase arbitrarilly consistent with a net decline in emissions. There are other constraints on population and productivity such that it is likely that we need to limit population growth and growth in per capita productivity (and hence consumption) cannot be very large; but a determination to reduce GHG emissions in no way commits us to reducing either.
2) Charlton's argument simply tries to impress you with large numbers without context. In context, 77 thousand km2 of solar panels, or 77 billion square meters of solar panels can be installed by each member of the current population installing 77.7 square meters of solar panels over a period of 25 years. Frankly, I could knock of my 77.7 square meters in a week.
To put that into more context, PV installation per annum is more than doubling world wide every year. Lets assume that falls of to an average effective growth of installations to 30% over 25 years. In that case, in the 25th year, 22.6 terrawatts will be installed per annum.
3) On current evidence it will not require a WW2 change in economies to combat climate change. In fact, if we get serious about it, the cost is likely to be about 1% of GDP, ie, significantly less than the US' peace time military budget.
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yocta at 15:59 PM on 14 May 2013It's too hard
I've just read two articles about humanity's future problems. Now they aren't journal articles, but the author (1) Albert Bartlett has written many peer reviewed articles on over population and (2) Andrew Charlton, is an academic
To a first approximation Bartlett states that 'the magnitude of the effect of humans in producing global climate change is proportional to the product of the size of the global population P and the average percapita annual consumption of resources, A
the total annual consumption of resources (tons per year).He argues that we must reduce both P and A simultaneously and rapidly throughout the world, and that there is no such thing as sustainable growth (the way we generally define it that is).
The second author I just read, was a quartily essary by Andrew Charlton (2), an advisor to the Australian Government at the Copenhagen Summit. He basically makes the case that as there are 1 billion rich people and 6 billion poor people. He quotes Saul Griffith, who in his study found that in order to reach the 2 degree mark would require the roll out of 13 Terrawatts globally over the nest 25 years.
To put that in perspective 2 terawatts of solar PVs, he calculates would reuire installing 100 square metres of solar cells every second for the next 25 years or 77,700km² of mirrors. (Tasmania is 68,401km²).
Basically, current technology cannot cut it.
Forgive my long post, but the question is, shouldn't the issue of population be looked at as cause in part of emissions? I have met my fair share of 'Libertarian' people who actually don't even believe there is such a thing as overpopulation.
And, am I correct in assuming we need a WW2 scale change in economies to actually achieve any emission reductions?Is this something SkS could look out?
The only way I see the way across the line is engaging with developing nations more than ever helping them get access to cheap clean energy.
(1) http://albartlett.org/articles/art_meaning_of_sustainability_2012mar20.pdf
(2) http://www.quarterlyessay.com/issue/man-made-world-choosing-between-progress-and-planet (*)
(*) a free sample can be found on Google Books -
KK Tung at 14:21 PM on 14 May 2013The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.
Reply to post 18 by KR: I did not assume that aerosol forcing is zero. I in fact think they are slightly larger than what has been used in GISS models, with the difference well within the range of uncertainty for tropospheric aerosols.
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KR at 12:09 PM on 14 May 2013The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.
Dr. Tung - Uncertainties in aerosol estimates do not mean you can assume extrema values for those aerosol forcings (such as the zero value you seem to use); the most parsimonious estimate is to use the best estimate of that data, as above. Zero is in fact entirely outside the 2-sigma range of aerosol estimates. If you assert that aerosol uncertainties are extreme enough to invalidate radiative forcing data, your own paper has nothing to stand on, as you are attempting to evaluate attribution between internal climate variability and anthropogenic radiative forcings including those aerosols.
Your assumption of linear anthropogenic influence since 1910 is invalid given the totality of observed forcings; which are clearly non-linear in sum. Invoking uncertainty there, however, does not support your work.
Regarding Enfield and Cid-Serrano 2010, I will note a few issues I have with that paper relative to yours:
* They first point out that 1-year lag times are perhaps too long for atmospheric/oceanic interactions, then base their claims of uncertain Granger causality on those 1-year lags. Note that their results are quite ambiguous in this regard, with roughly 50-50% splits depending on test variables and definitions - and that the same test with monthly lag testing indicates a best-fit with AMO lagging temperatures by 3 months.
* They do not support your methods, or a linear detrending, stating "We consider that Trenberth and Shea (2006) and Mann and Emanuel (2006) are quite correct about the desirability of defining the AMO in a way that accounts for the nonlinearity in AGW." I find it curious to see you claiming methodological support from that paper.
* Their detrending, "This can be achieved effectively and simply by subtracting a least squares-fit quadratic function from the time series..." is nearly as simplistic as a linear detrending, and again is not matched to the relevant radiative forcing data.
Finally, as I've noted repeatedly, with no reply on your part, the AMO and oceanic variability simply cannot supply the required energy for 40% of global warming under the energy constraints of rising ocean heat content. Even AMO-driven cloud changes as a possible (if not plausible) secondary mechanism would be insufficient due to their limited duration (they would require forcing changes several times observed) and spatial extent (hemispheric at the very most via teleconnection). Arguing over AMO definitions is a red herring if there is simply not enough energy available to support your conclusions.
I consider this last issue just as important as the AMO definitions - the influence of internal variability must be consistent with all the available evidence.
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Enfield and Cid-Serrano 2010 does not support linear detrending, uncertainties in aerosols can only weaken your own conclusions, and you have not addressed the energy balance issue in any way. I'm afraid I must continue to disagree with your conclusions.
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Rob Painting at 10:18 AM on 14 May 2013Another Piece of the Global Warming Puzzle - More Efficient Ocean Heat Uptake
Thanks Jos. Will draft up a post on the new Meehl paper.
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KK Tung at 10:02 AM on 14 May 2013The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.
Reply to post 14 by KR: How do you know what the total (net) radiative forcing is, given the uncertainty in aerosol forcing?
I did mention in part2 that the effect of removing a nonlinear trend was discussed by Enfield and Cid-Serrano (2010).
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KK Tung at 09:58 AM on 14 May 2013The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.
Replying to post 15 by Tom Curtis: The statistical significance of the AMO mode in the 50-80 year period in the CET data was shown in our PNAS paper.For the global mean data after 1850 it was shown in the appendix of that paper. The statistical significance of the same spectral peak in the multi-proxy data was shown by Delworth and Mann (2000).
Have you tried using longer-term moving average (longer than 10 years)? We did, and it did show up. Moving average is rather primitive and it is difficult to establish the statistical significance of what you generate. We used the wavelet low-pass and band-pass, and there is a well established procedure to establish statistical significance. -
KK Tung at 09:44 AM on 14 May 2013The anthropogenic global warming rate: Is it steady for the last 100 years?
Reply to post 49 and 50; By "almost" I didn't intend to imply more or less. The exponential function was used in my figure 1 to show that it almost fits the actually data. In the calculation done in Figure 2, the actual emission was used to calculate the radiative forcing. So this distinction of more or less than exponential is moot.
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SeaHuck5891 at 09:00 AM on 14 May 20132013 SkS Weekly Digest #19
Is SkS planning on doing an article about his NYTimes article? It is found under their series examining the "debate" (their words) surrounding climate change. I would like to see more details about the specific claims, as well as those making them.
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JosHagelaars at 08:14 AM on 14 May 2013Another Piece of the Global Warming Puzzle - More Efficient Ocean Heat Uptake
Interesting regarding this discussion is the latest paper by Meehl et al. A copy can be found here.
Figure 1 in this post is compared with 'accelerated warming' decades in their figure 2. Same energy flux at the TOA, but quite a different picture for the OHC trends.
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Tom Curtis at 07:46 AM on 14 May 2013The evidence for climate change WITHOUT computer models or the IPCC
Oriolus Trailli and Rob Painting, following up from a hint by 64jcl at Potholer's channel, I have found a reference to fossil coral on Devon Island, Nunavat (in the Canadian Arctic). The fossil formation spans an interval from 600 million years ago (ie, in the Pre-Cambrian and approximately the time of the last snow ball Earth episode) to 39 million years ago. The fossil corals, however, appear in the late Ordovician, or approximately 450 million years ago. If this is indeed the reference Potholer had in mind, he has confused the timing of the corals with the begining of the formation.
To place the timing of the coral fossils in context, here is the broad temperature history of the Earth:
The fossil corals appeared in the late Ordivician just prior to the partial glaciation indicated by the thin blue line. The chart has a resolution of 10 million years, so fluctuation of CO2 concentration by up to 2000 ppmv (with corresponding fluctuations in temperature) may have occured at finer resoltuions and not show up on the chart, so global temperatures at the time of the corals may have been several degrees above those shown in the chart. However, it also cannot be excluded that the fossils are of cold water corals.
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Tom Curtis at 07:04 AM on 14 May 2013The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.
KK Tung @12, I would be fascinated to hear what portion of variance in the annual temperature series you ascribe to seasonal temperature differences. Failing that explanation, I have to regard your introduction of seasonal temperature variation when annually resolved temperature differences are the finest resolution under discussion as a pure red herring. Ineed, I also consider the introduction of annual and ENSO variations a case of misdirection when the issue is that your AMO does not show up in the CET series using a 21 point binomial smooth, (described as equivalent to a 10 year moving average by the met office). A 10 year moving average would filter out merely annual variation, along with nearly all variation related to ENSO and the solar cycle. Indeed, if a 50-80 year oscillation does not show up with a 10 year moving average, the most parsimonious explanation is because it does not exist. And it does not show up in the 21 point binomial smooth (equivalent to a 10 year moving average) applied by the MET office to the CET.
Beyond noting your evasions, I note that you have not responded to the first, and key point, that the fifth RPC of MBH98, which you take to represent the AMO, represents around 3% of variance of the NH temperature reconstruction. It is not true for hemispheric temperture records that either the twentieth century warming (or the purported AMO) are much smaller than ENSO or annual variations in temperature. On the contrary, the "hockey stick" in MBH98 comes from RPC1, which explains 38.2% of the variance.
Finally, you are unclear regarding which "AMO" the CET shows statistically significant correlation to. Is it the "AMO" as seen in the 1850- present instrumental temperature set? In that case the lack of an AMO signal in the CET prior to 1850 is strong evidence that there was no such AMO signal prior to 1850. Or was it a correlation with the spurious RPC5? But that RPC is not statistically significant and therefore not a reasonable basis for asserting the existence of an AMO signal prior to 1850.
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Rob Painting at 07:03 AM on 14 May 2013Another Piece of the Global Warming Puzzle - More Efficient Ocean Heat Uptake
JoeT - Figure 1 is from model simulations with a global energy imbalance of 1 W/m2. The point being that the model demonstrates 'hiatus decades' even under strong global warming. That would likely be due to the changes in wind, as discussed above.
Balmaseda (2013) suggest the current top-of-the-atmosphere (TOA) radiative imbalance is larger than that found in the Loeb and Stephens papers.
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JosHagelaars at 05:52 AM on 14 May 2013Another Piece of the Global Warming Puzzle - More Efficient Ocean Heat Uptake
Dana, thanks for the informative post.
A copy of the Stephens paper can be found here:
http://www.aos.wisc.edu/~tristan/publications/2012_EBupdate_stephens_ngeo1580.pdf -
jdixon1980 at 03:57 AM on 14 May 2013The anthropogenic global warming rate: Is it steady for the last 100 years?
It will be interesting to see Dr. Tung's response to KR@49, assuming that Dr. Tung's conclusion rests on the premise that CO2 is increasing "almost exponentially" as opposed to "more than exponentially."
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dana1981 at 03:41 AM on 14 May 2013Another Piece of the Global Warming Puzzle - More Efficient Ocean Heat Uptake
JoeT - Figure 1 comes from Meehl 2011, so you'd have to check that paper (I don't have access to it). Measurements tend to vary between about 0.5 and 1 W/m2 though, depending on the data set and the paper you choose.
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JoeT at 03:32 AM on 14 May 2013Another Piece of the Global Warming Puzzle - More Efficient Ocean Heat Uptake
Dana, just to make sure I understand -- Fig.1shows the TOA imbalance at 1.0+/- 0.1 W/m2 at most. Is this a model estimate or a measurement? The Graeme Stephens paper has 0.6 +/- 0.4 W/m2 which is a satellite measurement. Is the Stephens' result still the best estimate of the imbalance?
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Composer99 at 01:52 AM on 14 May 2013The evidence for climate change WITHOUT computer models or the IPCC
I tried to make the point we need to examine the evidence with out the hysterics in the light of the actual measurements now coming available.
... on a post featuring a video consisting almost entirely of Peter Hadfield's dry, measured delivery.
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KR at 01:22 AM on 14 May 2013The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.
Dr. Tung - You are continuing to advocate using a linearly detrended AMO in your calculations, attributing some 40% of warming over the last 50 years to AMO variations.
A linear detrending would be appropriate if and only if warming from other influences over that period were linear. That, however, is not the case. The radiative forcings over that period are distinctly non-linear:
Hence a linear detrending will, as argued by Trenberth and Shea 2006, still contain non-linear portions of that signal, and will inappropriately reduce the global warming signal if subtracted - in effect subtracting a significant portion of overall global warming before attributing temperature changes. As they note:
About 0.45C of the SST anomaly is common to global SST and is thus linked to global warming...
Linear detrending does not isolate a SST anomaly from overall global warming; a 0.45C misattribution represents roughly 45% of observed warming over the last 50 years - and which matches to the 40% of warming you attribute to the AMO. A linear detrending is therefore inappropriate when attempting to attribute warming against variability.
It may well be (as I believe you have argued) that this becomes an argument of definitions, a chicken/egg question, with different answers based upon the AMO definition. To that extent, it is worth checking assumptions against additional data - for example the Anderson et al 2012 paper I referred to before, and which you have not commented upon. There an analysis of global warming against ocean heat content (OHC) indicates that more than a 10% warming contribution by natural variability is ruled out as inconsistent with observed OHC - if more was contributed by natural variability the oceans would have to be cooler.
The AMO cannot have contributed more than 10% of the warming signal over the last half-century based on conservation of energy, and the 40% attribution you make to the AMO is within 5% of what T&S estimate as misattributed to the AMO by linear detrending. Based on these issues alone, I would have to strongly disagree with your papers conclusions.
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Warren Hindmarsh at 00:14 AM on 14 May 2013The evidence for climate change WITHOUT computer models or the IPCC
Kevin come back tomorrow and I will explain it
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Kevin C at 00:02 AM on 14 May 2013The evidence for climate change WITHOUT computer models or the IPCC
Warren: Did you try the model I gave you?
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Kevin C at 22:44 PM on 13 May 2013The evidence for climate change WITHOUT computer models or the IPCC
Warren @9: This might interest you:
http://diyclimate.x10.mx/responsemodel/nbox.html
It's a toy 'empirical' climate model, which works by determining the climate sensitivity which best explains the observed temperature record from the forcings. It's got a lot of limitations, but it can provide a good cross-check on your intuition.
Go to the page, scroll down and set 'Years to fit' to 1880 - 1997. Now click Calculate. Underneath you'll see a figure for TCR (a measure of climate sensitivity over a human lifetime). You should get a number like 1.58C.
Now change 1997 to 2011, to include the most recent data available to the model and hit calculate. Note that including the last decade and a bit increases the estimate of climate sensitivity.
Your intuition may rebel against this, but think about it for a bit. If you can't work out why, come back tomorrow and I'll explain it.
[Note: I'm not claiming validity for the model, only that intuition is unreliable concerning the interpretation of recent temperature trends.] -
XPLAlN at 21:47 PM on 13 May 2013The evidence for climate change WITHOUT computer models or the IPCC
@mcooke #2
at 3:45 - 3:53 we are told that "a doubling of Co2 from pre-industrial levels will lead to a rise in average global temperatures of about 1 degree Centrigrade". And that at 5:30 - 5:39 - "for a doubling of CO2 concentrations we should see a rise in global temperatures of between 2 and 4.5 degrees" This might cause some confusion
...except the video content between the two points is actually an explanation of how one gets from one figure to the other - namely positive feedback due to water vapour. -
Tom Curtis at 21:12 PM on 13 May 2013The evidence for climate change WITHOUT computer models or the IPCC
Warren Hindmarsh @9, the global climate warmed at a rate of 0.071 C per decade durring the twentieth century (1901-2000). In contrast, it warmed at 0.108 C per decade from Oct 1994 to the present, the longest period of statistically insignificant warming (for Gistemp). That is, in this supposed warming pause, the Earth has been warming more than 50% faster than the record breaking Twentieth century rate of warming. Only in the wierd world of climate change denial can the rate of warming be significantly above average but it be called a warming pause solely because the chosen time interval is too short to contain enough measurements for statistical significance.
Now, can you explain to me without the deceptions why a warming rate greater than the twentieth century average, and very close to the predicted rate once known confounding factors (ENSO etc) are accounted for requires us to fundamentally reconsider the theory?
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Rob Painting at 20:25 PM on 13 May 2013Another Piece of the Global Warming Puzzle - More Efficient Ocean Heat Uptake
R Gates - Increased heat transport into the deep ocean is broadly consistent with what is known about the wind-driven ocean circulation. Stronger tropical easterly trade winds during La Nina-dominant periods (negative Pacific Decadal Oscillation [PDO]) will lead to stronger Ekman pumping in the ocean gyres. Indeed, one can see the piling up of water in the Western tropical Pacific in the sea level trend over the period of satellite altimetry (1993-to present) - a clear sign of the intensified winds there. Additionally, the intensified winds of the mid-latitude westerlies, and a poleward shift of the strongest winds toward the Antarctic Circumpolar Current will also lead to stronger convergence of surface currents, and stronger downward heat transport.
This will throttle back when we enter a period of El Nino-dominance (positive Pacific Decadal Oscillation) because the easterly trade winds will weaken. Less heat will be mixed into the deep ocean and more will remain at the surface - to be exchanged with the atmosphere. So, even though global warming will slow during that time, surface warming will speed up.
John Brookes - light-blocking sulfate pollution from global industrial activity has been declining since about 2007. This is primarily from the installation of scrubbing technology in Chinese smokestacks.
It is interesting, however, that the slowdown in ocean heat content accumulation during 2004-2007/2008 coincides with a strong global dimming during that interval. There is a tendency to ascribe changes to only one variable, but in reality a combination of variables may explain recent events.
There is the worrying possibility that 3 variables may have acted to slow surface warming during that time; the negative phase of the PDO, industrial sulfate pollution, and increased sulfates from increased volcanism of tropical volcanoes. Let's hope that that wasn't the case - it would imply significant surface warming when these 3 are no longer holding back greenhouse gas warming.
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Dikran Marsupial at 20:04 PM on 13 May 2013The evidence for climate change WITHOUT computer models or the IPCC
Warren "no statistical warming" does not mean "no warming", it just means that the observations do not effectively rule out the possibility that there has been no warming over the period in question.
If you want a statistical test to show there has been no warming, you need to show that the observations are inconsistent with the extistence of a warming trend of the magnitude suggestsed by the IPCC. If you do this you will find that the evidence for no warming isn't statistically significant either. Curously the "skeptics" never actually do this ;o)
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Rob Painting at 19:41 PM on 13 May 2013The evidence for climate change WITHOUT computer models or the IPCC
Warren - Global warming has accelerated. Only by excluding all the evidence for warming and focusing on the (roughly) 2% of global warming that goes into heating the atmosphere, and only over a short period of time, does it appear otherwise.
I'm sure that you'll agree that looking only a one small piece of the evidence is not a valid scientific approach.
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shoyemore at 17:07 PM on 13 May 2013The evidence for climate change WITHOUT computer models or the IPCC
Warren #9
No one should really take seriously statements likes no statistical warming for nearly 20 years despite increase of CO2 (or 17 years, or 15 years). That has been oft-refuted here and on other blogs.
www.skepticalscience.com/short-term-variability-vs-long-term-trends-mclean.html
www.skepticalscience.com/watanabe-et-al-2013-another-piece-of-the-puzzle.html
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Warren Hindmarsh at 16:07 PM on 13 May 2013The evidence for climate change WITHOUT computer models or the IPCC
We all know CO2 is a green house gas, we all know atmospheric CO2 increases alone won't force significant warming by it self, we all know forcing by H2O in the atmosphere will multiply the CO2 effect. What isn't certain yet is the value of the forcing by H2O. because the actual measured results - (-snip-)? Maybe we need to go back to the basics with a fresh look at this, (-snip-).
Moderator Response:[DB] Sloganeering and inflammatory tone snipped.
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R. Gates at 15:35 PM on 13 May 2013Another Piece of the Global Warming Puzzle - More Efficient Ocean Heat Uptake
I am still unconvinced of the overall thermodynamics behind the notion of "ocean heat uptake efficiency". I have no doubt mind you, that the bulk of the TOAenergy imbalance from increases in GH gases can be be found in the ocean at various depths, but what I seriously question is the direction of energy flow in accounting for the accumulation of about 0.5 x 10^22 joules per year of energy down to 2000 meters, and more when looking at even greater depths.
Given that the vast majority of energy in the oceans comes from solar SW, and that the net flow of energy planet wide is from ocean to the atmosphere, and that at any given time somewhere around 1/3 of the energy in the atmosphere came via the oceans, it seems far more accurate thermodynamically to speak about a slowdown in the transfer of energy from ocean to atmosphere. This is precisely what we see on a net basis during periods of La Niña activity or the cool phase of the PDO. Moreover, increased GH gases in the atmosphere would be expected to have the precise effect of slowing the rate of energy flow from ocean to atmosphere to space via several mechanisms. Finally, given the measured a increase in advection of energy to the Arctic via ocean currents, the increase in energy of the oceans should be expected to have the exact effect we are seeing with a rapidly declining Arctic Sea ice volume, with a great deal of this happening from ice being melted from underneath.
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John Brookes at 15:30 PM on 13 May 2013Another Piece of the Global Warming Puzzle - More Efficient Ocean Heat Uptake
Which makes you wonder if something similar was happening in the hiatus in temperatures in the middle of last century. But I imagine we didn't have accurate ocean heat content measurements then.
If our current models accurately modelled the absence of surface warming from 1940 to 1980, and did not include heat transport to the deep ocean, then maybe other assumptions of these models are questionable. For example, the amount of aerosols in the atmosphere may have been overstated to explain the cooling, when it was actually heat moving to the deep oceans.
This certainly is a good chance to improve the models!
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Bob Loblaw at 14:22 PM on 13 May 20132013 SkS Weekly Digest #19
Chris:
It's not the result of a wave carrying the ice that far up the beach. It's an "ice push". Get a long lake, a strong wind, and a lot of loose, moving ice, and there is a lot of momentum behind it. Ice gets pushed up on shore, and pushed further by more ice getting pushed ashore, and so on. It's like trying to stop an oil tanker.
Although such ice pushes are uncommon, I have been on many lakes in the Northwest Territories where the rocky beaches (typically made of rocks 10-20cm in diameter) have many ridges in the beach itself caused by such ice pushes. The ridges are easily several metres above normal water level, and there will be several of them at different heights, from different ice push events of varying strength.
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