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Tom Curtis at 10:18 AM on 25 May 2012Modeled and Observed Ocean Heat Content - Is There a Discrepancy?
From Peru @9, with one important quibble, I agree with all that you say. However, the graph you showed shows a 0-2000 m GISS-ER predicted OHC that is well within error of the 0-2000 m OHC observed by Levitus et al. Consequently, I am unsure why you call it "ugly", nor why you think fake "skeptics" would like to use it. I suspect in the updated chart, the the predicted change in OHC will exceed the observed, but unfortunately do not have an updated graph to directly confirm it. That said, Dana extensively discusses this issue in the original post. He surveys a variety of observational estimates, most showing change in OHC of around 0.5 W/m^2, which compares to the 0.6 W/m^2 (GISS-EH)or 0.7 W/m^2 (GISS-ER). Given the differences in volume and time periods involved, it is difficult to assess if, and to what extent either model is in error, all though GISS-EH appears to do quite well. The important quibble is that, by changing the temperature of the Earth's surface, oceanic oscillations will change the radiative balance through changes in cloud cover and humidity (and other feedbacks). Specifically, if climate forcings have a positive feedback compatible with IPCC predicted climate sensitivities, decreasing global temperatures will result in a lower reduction in OLR than would otherwise be the case. In contrast, if feedbacks are negative, decreasing global temperatures will result in a larger reduction in OLR than can be accounted for by temperature differences alone. In the former case, a transition from El Nino to La Nina conditions will result in a reduction in the expected TOA energy imbalance. -
From Peru at 09:18 AM on 25 May 2012Modeled and Observed Ocean Heat Content - Is There a Discrepancy?
Tom Curtis: "The only real problem is that the model does not predict a hiatus period. As hiatus periods are associated with ENSO activity, this is not entirely surprising." The hiatus is a situation where the heat from radiative forcing is transferred to the deep ocean more efficiently, mainly because the ENSO system is dominated by the La Niña phase, with the consecuence that there is less heat in the upper ocean to warm it. It explains the slowdown of the upper 700 m increse in OHC (or at least part of it) and the flatness of sea surface temperature timeseries in the last decade. However, ENSO do not create or destroy heat (nor any other oceanic oscillation), just redistribute it. So, if the radiative forcing remains constant, and the upper ocean warms less, the deeper ocean must warm more. (By the way, Bob Tisdale might have discovered just this when he blames all global warming on the big El Niños (and their aftereffects) of the last 40 years. Too bad he do not consirered the law of conservation of energy when he claims that ENSO can warm the Earth without an external forcing) However, even going to 2000 m deep, the warming appear in some datasets to have slowed. This could be due to measurement errors, but is likely true because in the last decade there was a deep solar minimum and an increase in cooling aerosols emissions from Asia -
Tom Curtis at 08:46 AM on 25 May 2012Modeled and Observed Ocean Heat Content - Is There a Discrepancy?
dana@7, in FromPeru's chart, the final intersect between the extension of the 0-750 m predicted OHC and the 0-700 m observed from Levitus is in approximately 2007. In contrast, in the figure you show, the predicted 0-750 m OHC does not intersect the Levitus 0-700 m OHC after approx 1997. By visual inspection, there is no obvious difference in the baselining. That being the case, I am fairly certain FromPeru's chart is not an updated chart, even though it is listed as such in the RC post. Regardless, the chart shown on the RC post is the same chart as that shown if you follow the link to the "uncorrected" chart. So, either Gavin has accidentally displayed the uncorrected chart in the post, or accidentally linked to the corrected chart instead of the uncorrected chart. (Or I need to see an optometrist.) -
dana1981 at 08:34 AM on 25 May 2012Modeled and Observed Ocean Heat Content - Is There a Discrepancy?
Tom @5 - that graphic is updated. The previous version showed a better match between GISS-EH and Levitus data, but that was due to a mistake on Gavin's part, treating the model simulation as being in units of ocean rather than global surface area. There is a modest discrepancy between both 0-700 and 0-2000 (vs. full ocean) data and models there, but as I said, it's just one model (and in fact just an extrapolation of the mean of 5 simulations with that model), and just one OHC data set. Gavin's light blue line represents the ~0.7 W/m2 full ocean OHC GISS-EH mean model run, vs. the OHC observations generally being around 0.5-0.6 W/m2. -
dana1981 at 08:29 AM on 25 May 2012Modeled and Observed Ocean Heat Content - Is There a Discrepancy?
From Peru @4 - the answer is that particular graphic only shows GISS-ER vs. Levitus data. As noted in the post above, GISS-EH matches most OHC reconstructions better than GISS-ER, and Domingues (2008) shows several other models as well. -
Tom Curtis at 08:27 AM on 25 May 2012Modeled and Observed Ocean Heat Content - Is There a Discrepancy?
From Peru @4, that figure is drawn from the Real Climate post of Feb 8th, 2012. Unlike the other RC posts in which an OHC chart has been updated, the currently displayed chart does not note the update. Further, on visual inspection, I can find no difference between that chart and the chart you find if you follow the link to the uncorrected chart. This strongly suggests to me that the chart you show is not a corrected chart, but rather than Gavin has accidentally linked to the old chart when making his update. In any case, the chart you show shows essentially no discrepancy between model and data for 0-2000 m, and good correlation for 0-700 (750) m. The only real problem is that the model does not predict a hiatus period. As hiatus periods are associated with ENSO activity, this is not entirely surprising. -
empirical_bayes at 08:18 AM on 25 May 2012Hansen and Sato Estimate Climate Sensitivity from Earth's History
@HumanityRules, #6 03:13 AM on 24 May, 2012: It is hard to to see how the Schmittner curves mix. (snip)Moderator Response: TC: Of topic text snipped. I would greatly enjoy further exploration of the snipped text in a thread where it is on topic. Unfotunately it is off topic here, and consistency requires that I moderate based on compliance with the comments policy, not personal agreement or disagreement with points being made. -
From Peru at 07:45 AM on 25 May 2012Modeled and Observed Ocean Heat Content - Is There a Discrepancy?
There is a corrected graph that is very ugly:
The "skeptics" will surely use it everytime they can.
What answer can be given to them (and specially to the true skeptics that are victims of the disinformation that the fake skeptics spread everywhere)?
There are any models that, unlike the ones shown in the figure, follow reality?
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dana1981 at 07:24 AM on 25 May 2012Modeled and Observed Ocean Heat Content - Is There a Discrepancy?
Albatross @2 - I certainly agree that relying on one's eyecrometer is rarely a good idea. Particularly when comparing data across different timeframes or different parameters (i.e. 0-700m vs. 0-2000m) - in that case the eyecrometer is essentially useless. That's why I wanted to try and do the analysis properly, to see if the numbers show there really is a discrepancy. As the post notes, it's hard to say, but it's possible (the uncertainties are just too large to say for sure either way). Certainly nowhere near a factor of 2 discrepancy though. -
Albatross at 06:58 AM on 25 May 2012Modeled and Observed Ocean Heat Content - Is There a Discrepancy?
Dana, In addition to the disinformation that "skeptics" are spreading on this issue, Roger Pielke Senior continues to try and undermine Levitus et al. (2012) (and James Hansen's research) by making unsubstantiated and subjective assertions/challenges. Pielke Senior claims that "This is a discrepancy of ~2 between his prediction and the analysis of Levitus et al 2012 if the latter observational analysis is correct." This is incorrect. One has to compare the data for the same time windows and for the same depth range. Comparing a rate for 1955-2010, with one for 1993-2003 as Pielke does is ludicrous. Pielke Senior then goes on to try and defend his (incorrect) conclusion by claiming that "While one possibility is that the rate increased after 1993 compared to earlier in the 1955-2010 period, but visually (using the eyecrometer) this does not seem to be the case." I do not know why Pielke chooses to rely on the notoriosly innacurate and subjective "eyecrometer" method when one can download the Levitus et al. (2012) data and calculate some statistics. Additionally, Pielke is applying his eyecrometer to the 0-2000m data here (the image from Levitus et al in his post) while actually making reference to the 0-700 m data. So instead of using the "Pielke eyecrometer™" let us look at the 0-700 m data for Levitus et al. shall we? The slope for 1955-2011 for 0-700 m is 0.26x10^22 J/yr, while for 1993-2011 the slope is 0.58x10^22 J/yr. So the slope from 1993 to present is more than double that for 1955-2011. Pielke Senior also alleges that "Levitus et al 2012 may be overstating the magnitude of recent upper ocean heating as clearly seen in the figure below from NOAA’s Pacific Marine Environmental Laboratory" This is simply not true. Analyzing the Pacific Marine Environmental Laboratory (PMEL) data (available here) we get a rate/slope of 0.78x10^22 J/yr between 1993 and 2011, which is greater than the rate (0.58x10^22 J/yr) obtained using the Levitus et al. data for the same depth range and the same period. So reality is again the complete opposite to Pielke's assertion and his "Pielke eyecrometer™" is telling him. Pielke Senior is engaging in very bad scientifc practice when he makes grandiose (and as it happens incorrect)proclamations based on nothing more than subjectively eyeballing graphs. -
zinfan94 at 05:44 AM on 25 May 2012Hockey stick is broken
There is a recent paper by Gergis et. al., discussed yesterday in a post on RealClimate site, that covers proxies for Australia and Oceania and results in a hockey stick. it would be interesting to see this SH Australasia hockey stick from Gergis(2012) compared to the Mann(2008) hockey stick, on the same timescale, displayed one above the other. I used the Gergis image from RealClimate, and the Mann image from the SkS site, and there seems to be some interesting agreement periods. For example, the sharp drops in proxy temperatures around 1350 and 1460 are present in both records, as near as I could see. From what I understand, sometimes the NH and SH temperatures will march together, and other times be out of phase. Perhaps SkS could discuss the two proxy records, comparing the temperature swings, written by someone knowledgeable of likely temperature swings over the last 1200 years. -
dana1981 at 02:50 AM on 25 May 2012Modeled and Observed Ocean Heat Content - Is There a Discrepancy?
Also kudos to Gavin Schmidt for so quickly noting and correcting the mistake in his prior model-data comparison posts. That's how true skeptics behave. -
Martin A at 23:59 PM on 24 May 2012CO2 has a short residence time
Dikran M: Thank you - I'll go back and look more carefully at your paper. I had thought the examples I had worked out (including the one above) had shown that residence and adjustment times were the same for a 1st order linear system. I think you are quite right. It makes good sense to reconcile your model and mine before introducing any further complications. -
dana1981 at 15:17 PM on 24 May 2012Hansen and Sato Estimate Climate Sensitivity from Earth's History
Fair point Tom, they certainly consider various LGM temperature reconstructions which use both terrestrial and ocean data. -
Tom Curtis at 14:23 PM on 24 May 2012Hansen and Sato Estimate Climate Sensitivity from Earth's History
dana, thank you for clarifying about the qualitative nature of the ESS. With regard to your discussion with HR, I believe he has overstated his case, but is correct that H&S use terrestrial data in determining the climate sensitivity. H&S use the ocean core data to establish relative temperature over the last 800,000 years, and show that, with their estimated forcings and a fast feedback sensitivity of 3 degrees C per 4 W/m^2 of forcing, predicted and observed temperatures correlate near perfectly. However, as they note, an equally good correlation would be achieved if temperatures and sensitivity were each scaled by the same factor. Therefore, different assumptions about global temperatures at the LGM result in different, and consistent estimates of the fast feedback sensitivity. As they say:"Global temperature change calculated by multiplying the sum of the two climate forcings in Fig. 5c by climate sensitivity ¾°C per W/m^2 yields a remarkably good fit to the "observed" temperature (Fig. 6). The observed temperature is based on the assumption that 4.5°C is a reasonable approximation of the LGM-Holocene surface temperature change, and thus a scale factor of 2 is used to convert δ 18 O deep ocean temperature change (equation 6) to surface temperature change. However, we could obtain an equally good match between the temperature calculated from the forcings and the temperature from δ 18 O if we assumed the LGM-Holocene warming was 6°C and fast-feedback climate sensitivity was 1°C per W/m^2 , or if we assumed that the LGM-Holocene warming was 3°C and climate sensitivity was 0.5°C per W/m^2. If LGM cooling is so uncertain as to be anywhere in the range 3-6°C, we can only conclude that the fast-feedback climate sensitivity is 3 ± 1°C for a 4 W/m^2 CO2 forcing. Thus accurate knowledge of the global temperature change between glacial and interglacial states is needed for empirical evaluation of fast-feedback climate sensitivity."
In order to constrain the temperatures at the LGM, Hansen and Sato discuss a variety of estimates, noting the inconsistency of sst based estimates such as CLIMAP and MARGO and terrestrial proxies. Finally, they state:"Given the inconsistencies among proxy data sets, our present assessment of global LGM cooling must be partly subjective. Our central estimate, 4.5°C, chosen with cognizance of discussions in the past three decades as new data sets were compared with CLIMAP, is in the middle of the range in the paleoclimate literature. Given that a global atmospheric model driven by CLIMAP sea surface temperatures yields LGM cooling of 3.6°C (Hansen et al., 1984), and indications that CLIMAP sea surface temperatures are incompatible with terrestrial data as well as with some marine data, we believe it is unlikely that global LGM cooling was much less than 4°C. On the high side, we argue that it is unlikely that global LGM cooling was much more than 5°C, because (1) LGM Antarctic cooling averaged over the Vostok (Vimeux et al., 2002) and Dome C (Jouzel et al., 2007) sites was 8-9°C, while both climate models and empirical data typically yield polar amplifications of quasi-equilibrium temperature change close to a factor of two, (2) despite disagreements about LGM ocean temperatures, there is general agreement that LGM cooling was limited in the tropics and subtropics."
Thus they explicitly adopt an estimate greater than those based on CLIMAP and MARGO, and explicitly do so because of the inconsistencies with terrestrial data. However, they do not simply adopt an estimate based on terrestrial data, which would lead to a temperature estimate for the LGM closer to 6 degrees C below the pre-industrial average. -
HumanityRules at 13:23 PM on 24 May 2012Hansen and Sato Estimate Climate Sensitivity from Earth's History
From section 5 "Our estimate of LGM global cooling is thus 4.5±0.5°C," "Our estimated LGM-Holocene forcings with 1σ uncertainties are 3±0.3 W/m2 for GHGs" I'd agree they are deriving these figures from a 'review' of other work but they seem to be presenting there own opinion as well. The second quote you use is from this section also. It actually seems like a strange add-on to the paper, I'm not sure of the purpose of it. -
dana1981 at 13:11 PM on 24 May 2012Hansen and Sato Estimate Climate Sensitivity from Earth's History
HR @10 - yes, HS12 only uses ocean core data for their temperature reconstruction. In the section you quote they're only talking about other studies. -
HumanityRules at 13:08 PM on 24 May 2012Hansen and Sato Estimate Climate Sensitivity from Earth's History
(Section 5 of Hansen's paper) -
dana1981 at 13:06 PM on 24 May 2012Hansen and Sato Estimate Climate Sensitivity from Earth's History
Tom @9 - the first section is just an introduction, and Figure 1 is labeled as a schematic in the caption. However, I have added a note about the greater uncertainty regarding long-term sensitivity in the ESS section in the post. -
HumanityRules at 13:02 PM on 24 May 2012Hansen and Sato Estimate Climate Sensitivity from Earth's History
Dana says "HR @6 - Hansen's temperature estimates in this case are based on deep ocean δ18O." Are you sure? We are both talking about the LGM section of the paper? We're Hansen talks about "the less ambiguous terrestrial data" and where he criticizes Schmittners use of MARGO (oceanic) data? The deep ocean stuff seems to relate to the Cenozoic part of the paper. -
amhartley at 10:36 AM on 24 May 2012If you want them to remember, tell a story
How could I fail to mention the parables of Jesus? "I will open my mouth in parables, I will utter what has been hidden since the foundation of the world." (Matt. 13:35) Not all parables were stories, but most were. -
Muzz at 09:20 AM on 24 May 2012If you want them to remember, tell a story
Exactly the technique used by Australia's own Climate Commissioner. He's brilliant at it. -
Bob Lacatena at 09:17 AM on 24 May 2012New research from last week 20/2012
From Peru, I'm not sure why you don't see the data you want at the NOAA site. For instance, look at this page and click "Get Yearly Data" near the bottom. -
Tom Curtis at 09:13 AM on 24 May 2012Hansen and Sato Estimate Climate Sensitivity from Earth's History
Dana, I believe your first section is insufficiently clear. H&S 2012 refine their previous estimates of the fast feedback climate sensitivity using empirical data over the last 800,000 years. However, there representation of slow feedback climate sensitivity is characterized as a "schematic", and is not an empirical result. They highlight certain empirical events such as the PETM, and from features of those events, deduce qualitative features of the Slow Feedback Climate Sensitivity - but that does not make that figure an empirical conclusion. As an example, the entire justification peculiar peak in the center of the Fast Feedbacks plus Albedo curve (just to the right of holocene conditions is:"Also, in sketching the Earth system climate sensitivity we bear in mind the possibility of a hysteresis effect that makes demise of the Antarctic ice sheet difficult, thus stretching out toward larger forcing the ice sheet addition to the fast-feedback sensitivity."
Hysteresis with respect to the Antarctic Ice sheet is probably a significant factor in Earth System Sensitivity, but it may modify the curve by first depressing it than elevating it, ie, by introducing a sine wave pattern rather than a simple peak. The reasoning does not even justify the shape of the curve, let alone the magnitude of the effects. I do not fault Hansen and Sato on this, as they are quite clear that their figure 7 (your figure 1) is a "schematic". I think that important qualification is eroded, however, when you describe the graph as their "climate sensitivity conclusions". -
funglestrumpet at 08:51 AM on 24 May 2012If you want them to remember, tell a story
Vroomie @ 1: From cars to karst - was it a bumpy ride? You may have hit on why Monckton is so popular. He in effect tells a story along the lines of a fairytale that climate change is no problem. And like Bill Harly, he puts on a show while telling it. -
From Peru at 07:57 AM on 24 May 2012New research from last week 20/2012
Sphaerica: Thank you for the link, (where I found the PDF of the paper) but ... ...I still don't find from where do Levitus et al. obtained the pre-2005, 2000-meter deep Ocean Heat Content and Thermo-Steric Sea Level Rise (in the paper, Figure 1 show the World Ocean Heat Content for the 2000m deep layer since 1955). -
funglestrumpet at 07:11 AM on 24 May 20122012 SkS Weekly Digest #20
re Ocean Acidification See Ted Talk: 'Melissa Garren: The sea we’ve hardly seen' and the anwer to your question is 'probably not' -
jimspy at 06:42 AM on 24 May 2012If you want them to remember, tell a story
Vroomie #1: From race car mechanic to geologist?? I'll bet THAT'S a good story in itself! -
kampmannpeine at 06:38 AM on 24 May 2012If you want them to remember, tell a story
beautiful article. I just gave some 90 minute talks about climate change facts ... for a general public of our region here in Germany (Hannover) ... I had to struggle for stories around the very harsh and dry topice. Grace to God my wife - an excellent teacher - helped me a lot (though not being a scientist) and she attended the talks just for giving me feedback afterwards ... a super experiment. Thanks Tom - we need more of that kind ... -
Tom Curtis at 05:19 AM on 24 May 2012Hansen and Sato Estimate Climate Sensitivity from Earth's History
HumanityRules @6, Hansen & Sato's estimate of 3 degrees C per 4 Watt/meter squared of forcing is equivalent to 2.8 C per doubling of CO2 (1 sigma uncertainty - 2.3-3.2 C). That would be closer to splitting the difference between Schmittner et al's land and ocean estimates. -
vrooomie at 04:50 AM on 24 May 2012OA not OK part 20: SUMMARY 2/2
JMurphy@18: I owe you a thank-you: For the most part, I long ago learned to avoid WUWT, on the basis that I actually like reading *real* scientists' views (why I'm here) and getting an ever-increasing level of revulsion for what *passes* as real science at various denialist's (WUWT). I did take the time--ugh--to wadethrough that link w/Happ and am now even more delighted to be a part of this resource.Re: the Happ link and his website? Talk about a 'Dunning-Kruger bingo game!" Thanks to all here. -
CoalGeologist at 04:33 AM on 24 May 2012Dear Heartland, Stop using Arthur Robinson's Trick to Hide the Incline
Good work. I appreciate your documentation of efforts by AGW Denialists to silence the expression of skeptical viewpoints. (They commonly, and with little actual justification, accuse the mainstream science community of the same offense.) The key issue here is that the present day Sargasso Sea SSTs are significantly higher than indicated in the diagram by Robinson et al. (2007). This is fairly clear, but I'm still uncertain regarding a few minor details. The following graph is an overlay of parts of three of your figures. It's a bit of a mess, but I hope it will serve. The base graph is the 6th one (above).
Your 1st diagram includes SST data from Station "S". These appear on my overlay as the squiggly line centered around 23°C, at approximately 1996. It is my understanding that this represents data from 1954 up to the time the paper was published in Keigwin (1996). These same (??) data appear as the black dots on the base diagram, beginning in 1954, extended up to the present. The green line presumably represents a linear best-fit (although this is not specified). Can you explain the apparent discrepancy between these two representations of the data?
Your 7th diagram indicates a "2006 temperature based on stated method", slightly higher than 24°C, but I didn't see where you state the method. This point differs from the "best fit" value indicated on the base diagram, although it does seem to fit the surrounding data from the base diagram.
Finally, you refer to the Heartland Institute as "a fossil-fuel-funded political pressure group". The recently leaked documents from Heartland indicating their funding sources did not appear to me to support this comment. Can you indicate what you base it on? Thanks.
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IanC at 04:07 AM on 24 May 2012CO2 has a short residence time
Dikran, Ah I see. I originally thought in 131 you are referring to the residence time for C14 and adjustment time for a perturbation of C14, which clearly are the same from the data. I tried explaining this from a more general model, and thought the large initial perturbation will lead to simplifications in the fluxes that will give you this result. Turns out this is unnecessarily complicated: after reading your paper again I realised that your model for the anthropogenic CO2 component can be applied to the C14 data with the addition of a source term, and all the right conclusions follow. -
dana1981 at 04:01 AM on 24 May 2012Hansen and Sato Estimate Climate Sensitivity from Earth's History
HR @6 - Hansen's temperature estimates in this case are based on deep ocean δ18O. -
Bob Lacatena at 03:44 AM on 24 May 2012New research from last week 20/2012
From Peru, From Dana's previous April 25 post here on Levitus 2012, it seems you can get the data here. -
From Peru at 03:32 AM on 24 May 2012New research from last week 20/2012
There is considerable activity in the (so called)skeptic field about this paper. For example, at WUWT: Trenberth’s missing heat still missing: new paper shows a near flat ocean temperature trend – 0.09°C over the past 55 years Clearly comparing the 1955-2010 trend with the current estimated rate of heating of earth surface (all in W/m^2) (i.e. the rate after the 1970s) is comparing apples to oranges. Where I can find the data for the paper "World ocean heat content and thermosteric sea level change (0–2000 m), 1955–2010" by Levitus et al. (2012)? With the data I can plot the ocean warming of the relevant periods (1975-2010, 1990-2003, 2003-2010, etc)to to compare it with the expectations of radiative imbalance caused by radiative forcing. -
HumanityRules at 03:13 AM on 24 May 2012Hansen and Sato Estimate Climate Sensitivity from Earth's History
"our present assessment of global LGM cooling must be partly subjective" (HS12) I don't see that much difference between Schmittner and HS12 except with regard to the quote above. Hansen likes the land paleo data more than ocean and as Schmittner shows his land based CS estimate is about inline with Hansen's.
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citizenschallenge at 00:25 AM on 24 May 2012Dear Heartland, Stop using Arthur Robinson's Trick to Hide the Incline
Thanks for the heads up, I love writing. . . hate my misspellings and typos. Incidentally, I polished up on the whole of it this morning and made it a stand alone post. SkepticalScience.com compared to WUWT.com -
CBDunkerson at 22:02 PM on 23 May 2012Hansen and Sato Estimate Climate Sensitivity from Earth's History
This is the first study I've seen which attempts to determine a complete spectrum of sensitivity values for all forcings relative to the current climate state. The finding that a 'runaway greenhouse' scenario would require greater than 8 W/m^2 forcing (i.e. two 'doublings' of CO2e, or 1120 ppm) is 'comforting' as that seems likely to be towards the upper end of our possible range of GHG forcing. That is, the point at which we would slip into a runaway greenhouse effect seems to be well beyond the point at which the damage caused by 'constrained' greenhouse warming would be sufficiently catastrophic to end further anthropomorphic GHG accumulations. I.E. it doesn't matter how stupid we are... we can't wipe ourselves out with fossil fuels alone. Yay? Presumably the prominent 'bump' in the equilibrium climate sensitivity at ~2-4 W/m^2 forcing is the albedo shift from the melting of Greenland and Antarctica. That's also very significant as it indicates that a 4 W/m^2 forcing sustained for thousands of years, which at this point is entirely possible, would result in the melting of the polar ice caps and the geological end of the Pleistocene epoch / current ice age. That would constitute a truly 'Anthropocene' geological epoch. One item of immediate concern is the convergence of the fast feedback and equilibrium sensitivity values at ~8 W/m^2 forcing. Does that suggest that the polar ice caps could melt within a hundred years at sustained 8 W/m^2 forcing? If so, we could be looking at a radically different world map by 2200. -
Kevin C at 20:08 PM on 23 May 2012Hansen and Sato Estimate Climate Sensitivity from Earth's History
Thanks Macoles, I hadn't picked up on the significance of that point. That goes a long way to addressing my question. -
macoles at 19:45 PM on 23 May 2012Hansen and Sato Estimate Climate Sensitivity from Earth's History
Very interesting paper that shows the dependency of historical climate forcing sensitivity on the accuracy of the historical temperature reconstruction used. As Hanson and Sato say themselves: "Global temperature change calculated by multiplying the sum of the two climate forcings in Fig. 5c by climate sensitivity ¾°C per W/m2 yields a remarkably good fit to the "observed" temperature (Fig. 6). The observed temperature is based on the assumption that 4.5°C is a reasonable approximation of the LGM-Holocene surface temperature change, and thus a scale factor of 2 is used to convert δ18O deep ocean temperature change (equation 6) to surface temperature change. However, we could obtain an equally good match between the temperature calculated from the forcings and the temperature from δ18O if we assumed the LGM-Holocene warming was 6°C and fast-feedback climate sensitivity was 1°C per W/m2, or if we assumed that the LGM-Holocene warming was 3°C and climate sensitivity was 0.5°C per W/m2. If LGM cooling is so uncertain as to be anywhere in the range 3-6°C, we can only conclude that the fast-feedback climate sensitivity is 3 ± 1°C for a 4 W/m2 CO2 forcing. Thus accurate knowledge of the global temperature change between glacial and interglacial states is needed for empirical evaluation of fast-feedback climate sensitivity." So their 3±0.5°C for a 4 W/m2 CO2 at 68% probability looks like it is directly based on their estimate of LGM global cooling being 4.5±0.5°C at 68% probability. Therefore I think the really interesting part of their paper is the Fig7 Equilibrium Climate Sensitivity chart more than the narrowed sensitivity itself. -
Kevin C at 18:32 PM on 23 May 2012Hansen and Sato Estimate Climate Sensitivity from Earth's History
The recent Hansen and Sato papers are easy to read, make very simple arguments, and are very compelling. The thing I can't judge as an outsider of course is whether his selection of source data realistically reflects the range of estimates in the field, and as a result if he is realistically including all the uncertainties. Someone who is more deeply read in the paleoclimate literature might be able to comment on that. I'd be interested to see a robust critique, but I don't remember any examples of anyone taking on Hansen in the primary literature. And I'm slightly bothered by how round the numbers always are. S_ff is always 3C, and the uncertainty is always a round number. That's a stupid criticism, because it's probably just a desire not to implicitly suggest a greater precision, but it bothers me slightly. -
citizenschallenge at 17:48 PM on 23 May 2012Dear Heartland, Stop using Arthur Robinson's Trick to Hide the Incline
Yup, another great informative article. well... and yes... I couldn't pass up bootlegging a copy onto whatsupwiththatwatts.blogspot That "embed code" is the coolest. Also I started a thread over at SkepticSocietyForum that might interest some of you. ~ ~ ~ ~ ~ ~ ~ "SkepticalScience.com compared to WUWT.com" _________________________________________________ Post #1 Postby citizenschallenge » Wed May 23, 2012 1:05 am "So you have problems with my sources and I have problems with your sources" ~ ~ ~ "I know some claim SkepticalScience.com is no different from WattsUpWithThat.com. "I have been told: "it's just a different perspective, you choose to believe SkepticalScience.com and I choose to believe WUWT.” But, is it as simple as that? How do we decide on the respective veracity of each? . . . " ~ ~ ~ ~ ~ ~ ~ {and so on and so forth...} Keep up the good work :-) cheers, peterModerator Response: TC: voracity --> veracity. Let me know if I've misunderstood, for I am pretty voracious ;) -
Dikran Marsupial at 17:12 PM on 23 May 2012CO2 has a short residence time
IanC The adjustment time and residence time in my paper are both for the atmosphere. IIRC there is a preferential uptake of "light" CO2, so C14 would have a slightly longer residence time, but there is so little of it it would have no real effect on atmospheric residence and adjustment times. Martin A No, it doesn't depend on the system being non-linear. The one-box model discussed in my paper is linear, but it has different residence and adjustment times. I don't think the basic physics of ocean uptake is contraversial. Siegenthaler and Sarmiento would be a good place to start. However it would probably be a good idea to reconcile the difference between your model and mine before going on to the oceanic uptake. -
Glenn Tamblyn at 16:24 PM on 23 May 2012Hansen and Sato Estimate Climate Sensitivity from Earth's History
HS12 narrowing the error margins on their CS value to +/- 0.5 C is pretty significant compared to previous values more like +/- 1.5 C. If their methodology stands up to scrutiny this is quite useful. And it should make the cut for AR5. -
Yvan Dutil at 11:48 AM on 23 May 2012New research from last week 20/2012
Note: I did not know where to put this comment without being out of topic. I taking my chance here It would be interesting to see if the correlation between temperature anomaly and solar cycle claimed in this paper will survived the transition from HadCRU3 to HadCRU4. "Reconstructed Total Solar Irradiance as a precursor for long-term solar activity predictions: a nonlinear dynamics approach" Stefano Sello http://arxiv.org/pdf/1205.4966.pdf The nice thing with this model is it will be easily proven/or disproven within 5 years at a 3 sigma level (see figure 9).Moderator Response: TC: For your convenience:
The plot is of HadCRUT3 Northern Hemisphere temperatures. Apparently, according to Sello Southern Hemisphere temperatures are not governed by solar activity /sarc. Until Dana adds Sello to his Lesson's from Past Predictions series, the best place to respond to this post is here -
Tom Curtis at 09:39 AM on 23 May 2012There's no empirical evidence
matzdj's questions @180 are either nonsensical or grossly misinformed. Take his first question as an example. His question assumes, falsely, that CO2 has a constant "absorption band" regardless of its concentration in the atmosphere. On the contrary, as the CO2 concentration increases, the current absorption band widens, and new absorption bands form, as can be seen by this comparison of modtran emission spectra for 375 and 999999 ppmv of CO2 in the atmosphere, and with no other greenhouse gases: 375 ppmv
999,999 ppmv
The Modtran model is reasonably, but not entirely accurate. In this instance it introduces a large inaccuracy by preserving atmospheric temperatures as if there was no change in CO2 content. If temperatures were allowed to adjust, the large W shape between wavenumber's 400 and 800 in the 99.99% example would be a large V or U shape instead, indicating much larger "absorption". The reason for this is that the outgoing spectra is not a product just of absorption of surface radiation, but also of radiation from the atmosphere.
For empirical comparison, here are the IR spectrums of the Earth, Mars, and Venus. Note that the absorption from Venus is from the surface radiation with a blackbody spectrum for 735 degrees K, not the 260 degrees K shown:
In his second question, matzdj assumes the Earth is just 700 meters deep by using the OHC record for only that portion of the ocean. He would have done far better to use the OHC record for the first 2000 meters of the ocean, as below:
Better yet, he should have used the data for the entire Earth, as in figure 4 above. So, "Isn't there information from NOAA that indicates that although Global Heat Content has risen over an extended period, it has recently done an abrupt levelling?"
Umm. No! Not unless you ignore the available evidence from NOAA that you find inconvenient.
Finally, in his third question, matzjd simply ignores the fact that the correlation between CO2 forcing and temperature was first predicted from physical principles around 200 years ago. The correlation of the Earth's temperature to large changes in CO2 forcing throughout Earth's history for at least the last 600,000 years (the period with any available data) did not come as a surprise to anyone. It was a predicted consequence of the observed fact that CO2 is transparent to visible light, and absorbs Far IR radiation, the observed fact that the Earth re-emits the energy received from the Sun, primarily as visible light and Near IR radiation in the Far IR spectrum, and that energy is conserved.
I have discussed extensively the experimental observations that make us confident of our understanding of the transmission and emission of CO2 in the atmosphere, and consequently make us certain that there is a greenhouse effect. As matzjd seems determined to ignore that evidence, here I shall simply show the correlation shown by the inexact (because of a lack of a precise temperature and humidity profile), and obsolete (1987 vintage) modtran model and observations:
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pbjamm at 09:35 AM on 23 May 20122012 SkS Weekly Digest #20
I am not sure this is right place for this but it certainly belongs on SkS.
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skywatcher at 09:26 AM on 23 May 2012There's no empirical evidence
matzdj, why do you post the same graph as you posted on the 17th May on another thread? Did you read the responses you were given (several detailed responses including at least nine links to follow from myself and DB)? Did you do any analysis to determine whether there has actually been a significant change in trend? Or are you just here to repeat tired old debunked talking points and not listen to the responses you were given? The graph you provide is not [ocean] heat content from NOAA - I provided you with the link to NOAA ocean heat content (the same as Rob's above) on 17th May. Until you do the analysis to determine whether there has been a change in trend, your comment is empty of substance in any case. -
Steve L at 09:25 AM on 23 May 2012If you want them to remember, tell a story
Folks might be interested in looking up Randy Olson ("Storyomics: proof that scientists evolved from humans" and "Don't be such a scientist: talking substance in an age of style").
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