RealClimate logo


Global warming and ocean heat content

Filed under: — gavin @ 3 October 2011

The connection between global warming and the changes in ocean heat content has long been a subject of discussion in climate science. This was explicitly discussed in Hansen et al, 1997 where they predicted that over the last few decades of the 20th Century, there should have been a significant increase in ocean heat content (OHC). Note that at the time, there had not been any observational estimate of that change (the first was in 2000 (Levitus et al, 2000)), giving yet another example of a successful climate model prediction. At RC, we have tracked the issue multiple times e.g. 2005, 2008 and 2010. Over the last few months, though, there have been a number of new papers on this connection that provide some interesting perspective on the issue which will certainly continue as the CMIP5 models start to get analysed.

The most recent paper was a new study from NCAR out last week that looked into what happens to OHC in models when there are occasional 10 year periods with no trends in global surface temperatures (Meehl et al, 2011).

It is well-known (or at least it should be) that simulations for late 20th C and early 21st Century do not produce monotonically increasing temperatures at the annual or decadal time-scale. For the models used in AR4, the decadal trends expected under estimates of present day forcings are roughly N(0.2,0.14) (i.e. a Gaussian distribution centered on 0.2 ºC/decade with a standard deviation of ~0.14ºC/decade. This implies that one would expect an 8% probability of getting surface temperature trends less than zero in any one decade.

The Meehl et al study looked at the changes in ocean heat content during these occasional decades and compared that to the changes seen in other decades with positive surface trends. What they found was that decades with cooling surface temperatures consistently had higher-than-average increases in ocean heat content. This makes perfect sense if there is internal decadal variability in the fluxes that connect the deeper ocean to the surface ocean (which of course there is). An anomalous downward heat flux reduces the ocean surface temperature (and hence global surface temperature), which generates an anomalous heat flux into the ocean from the atmosphere (because the flux into the ocean is related to the difference between atmospheric and ocean temperature). And this of course increases total OHC.

A related study from the UK Met. Office looked at the relationship between the ocean heat content changes in the top 700m and the total ocean heat content change in models (Palmer et al, 2011). They found that (unsurprisingly) there is more variability in the top 700m than in the whole ocean. This is important to quantify because we have better estimates of the upper ocean OHC change than we do of changes in the whole ocean. Observational studies indicate that the below-700m increases are not negligible – but they are poorly characterised (von Schuckmann et al, 2009). The Palmer study indicates that the uncertainty on the decadal total OHC change is about 0.15 W/m2 if one only knows the OHC change for the top 700m.

So what can we infer about the real world from these tests? First, we can conclude that we are looking at the right quantities. Total OHC changes are a good measure of the overall radiative imbalance. Second, there is likely to be a systematic issue if we only look at the 0-700m change – this is a noisy estimate of the total OHC change. Third, if the forcings are close to what we expect, we should anticipate that the deeper ocean (below 700m) is taking up some of the slack. There are of course shorter term sources of variability that also impact these measures (OHC changes associated with ENSO, solar irradiance variability over the solar cycle) which complicate the situation.

Two further points have come in comment threads recently that are related to this. The first is whether the changes in deep ocean heat content have any direct impact other than damping the surface response to the ongoing radiative imbalance. The deep ocean is really massive and even for the large changes in OHC we are discussing the impact on the deep temperature is small (I would guess less than 0.1 deg C or so). This is unlikely to have much of a direct impact on the deep biosphere. Neither is this heat going to come back out from the deep ocean any time soon (the notion that this heat is the warming that is ‘in the pipeline’ is erroneous). Rather, these measures are important for what they tell us about the TOA radiative imbalance and it is that which is important for future warming.

The second point is related to a posting by Roger Pielke Sr last week, who claimed that the Meehl et al paper ‘torpedoed’ the use of the surface temperature anomaly as a useful metric of global warming. This is odd in a number of respects. First, the surface temperature records are the longest climate records we have from direct measurements and have been independently replicated by multiple independent groups. I’m not aware of anyone who has ever thought that surface temperatures tell us everything there is to know about climate change, but nonetheless in practical terms global warming has for years been defined as the rise in this metric. It is certainly useful to look at the total heat content anomaly (as best as it can be estimated), but the difficulties in assembling such a metric and extending it back in time more than a few decades preclude it from supplanting the surface temperatures in this respect.

Overall, I think these studies show how we can use climate models to their best advantage. By looking at relationships between key quantities – those that can be observed in the real world and those that are important for predictions – we can use the models to interpret what we are measuring in the real world. For these cases the inferences are not particularly surprising, but it is important that they be quantified. Note that the assumption here is akin to acknowledging that since the real world is more complicated than the (imperfect) models, inferences in the real world should at least be shown to work in the models before you confidently apply them to reality.

However, it is the case that none of these studies prove that these effects are happening in the real world – they are merely suggestive of what we might strongly expect.


References

  1. S. Levitus, "Warming of the World Ocean", Science, vol. 287, pp. 2225-2229, 2000. http://dx.doi.org/10.1126/science.287.5461.2225
  2. G.A. Meehl, J.M. Arblaster, J.T. Fasullo, A. Hu, and K.E. Trenberth, "Model-based evidence of deep-ocean heat uptake during surface-temperature hiatus periods", Nature Climate change, vol. 1, pp. 360-364, 2011. http://dx.doi.org/10.1038/nclimate1229
  3. M.D. Palmer, D.J. McNeall, and N.J. Dunstone, "Importance of the deep ocean for estimating decadal changes in Earth's radiation balance", Geophysical Research Letters, vol. 38, pp. n/a-n/a, 2011. http://dx.doi.org/10.1029/2011GL047835
  4. K. von Schuckmann, F. Gaillard, and P. Le Traon, "Global hydrographic variability patterns during 2003–2008", J. Geophys. Res., vol. 114, 2009. http://dx.doi.org/10.1029/2008JC005237

283 Responses to “Global warming and ocean heat content”

  1. 51
    Alex Harvey says:

    Dear Gavin #3,

    Thank you for your responses. I assure you it is not my intention to set up any straw man.

    A while ago now Trenberth made a similar statement to the one you have just made on Argo and fluxes:

    http://pielkeclimatesci.wordpress.com/2010/04/19/further-feedback-from-kevin-trenberth-and-feedback-from-josh-willis-on-the-ucar-press-release/

    “On Sat, 17 Apr 2010, Kevin Trenberth wrote:
    Well of course any deep warming goes thru the surface layers but that requires detailed measurements far beyond Argo to track that flux. It can relate to MOC, convection, ENSO etc.”

    Pielke disagreed however:
    “I agree measuring the fluxes is a challenge. However, this is not needed in order to see heat transfer to lower levels. We just need to monitor the Joules in the layers from the sfc to say 700m to see the propagation of heat to lower levels. Unless the transfer were faster than the time interval of the measurements, this should be resolved by the available data.”

    I would think that even without accurate flux measurements, if heat was transferring through the upper 0-700m, the upper ocean would be seen to warm first. Is it your view that the heat could transfer faster than the time interval of the measurements – or is it that you think Pielke is wrong?

    [Response: Pielke's statement makes no sense. Transfers of heat are continuous processes. Upper ocean waters are indeed warming faster than those below and the temperature change in any one layer gives the net flux into that layer over time - i.e. what's coming in at the top, minus what is leaving at the bottom. The net fluxes in the upper-most layers can't be used to estimate the downward flux at 700m without more information (such as the incoming flux at the surface!) which is precisely what we don't have. Thus the only way to measure the heat flux into the deep ocean is either to measure the temperature changes there directly (hard), or model the advective and diffusive fluxes at the interface (very hard). - gavin]

    Regarding your comment on the Hansen et al. paper I admit I do not understand your response. I am not saying that this or that is a “contradiction” but it must at least be true that if Hansen has decided that the “missing heat” has probably been radiated away as a result of the aerosol forcing – and he says the same in a very detailed paper – this implies he disagrees with Trenberth and others that the missing heat is likely in the deep ocean. So it would be good to know exactly why Hansen and Trenberth seem to have come to opposite conclusions. I have not been able to work that out so far.

    Sincerely,
    Alex Harvey

    [Response: You asked me about Hansen vs. Meehl et al, not Trenberth. It should be obvious that if the forcings are less than Trenberth supposed because of higher aerosols and lower solar irradiance, then there is less heat 'missing'. It is not that it would have been 'radiated' away, but rather it was never here to begin with. But again, there is no contradiction - both Hansen and Trenberth agree that accurate estimates of the forcings are necessary, and they both agree that the deep ocean is where any remaining imbalance will end up. Nobody is absolutely wedded to a specific number for this. - gavin]

  2. 52
    isotopious says:

    So here is similar data to Fig 11 from Wanner et al.

    http://www.ncdc.noaa.gov/paleo/pubs/flueckiger2002/fig2.gif

    As you can see CO2 has been increasing since ~8000 years ago. The source of CO2 is from net ocean warming?

    If not, where is it from, keeping in mind the overwhelming importance of the ocean as a carbon sink?

    Anything misleading here, Tamino?

    [Response: How is this similar data? You were talking about temperature rises before. This is a figure of forcings. The CO2 increase over these timescales of ~1 ppm every 400 years (some 800 times smaller than current rates of change) might be due to continued rearrangements of the carbon cycle (including the ocean), and might be influenced by early human deforestation activity (Ruddiman's hypothesis) - it is a small change and so there are many candidate processes. It still doesn't demonstrate that the planet as a whole has been warming through the Holocene. (For reference, 20 ppm is a forcing of 5.35*log(280/260) = 0.4 W/m2, and, assuming a standard sensitivity, a temperature change of 0.04ºC per thousand years if this was the only thing going on (which, of course, it wasn't). - gavin]

  3. 53
    Bob Irvine says:

    Reading this it would be easy to forget that this whole discussion is based on modelling with no real world data supporting anything that has been said here. It surprises me that the only real world data that impacts on this subject has not even been mentioned.

    If the deep ocean is warming to balance decadal scale upper ocean cooling as most of the contributors here seem to believe, then you would expect this to show up in the thermal expansion contribution to sea level rise.

    Cazenove & Llovel 2009, Contemporary Sea Level Rise, have summarised the data in this area and found it does not support your conclusions.

    To summarise;
    From 1993 – 2007 they found sea level rose 3.3+-0.4mm/year with a thermal expansion component of 1.0+-0.5mm/year.
    From 2003 – 2007 they found sea level rose 2.5+-0.4mm/year with a thermal expansion component of 0.25+-0.8mm/year.

    There is clearly far less energy going into the ocean during the later atmosphere and upper ocean temperature hiatus (2003-2007)than there was when the atmosphere and upper ocean were warming (1993-2003). Since this study sea level rise has declined further and actually fallen over the last 2 years indicating that thermal expansion is now likely to be negative.

    The only reason that sea level rise from 2003-2007 was as high as 2.5mm/yr was that there was much higher ice sheet and glacial melt during this period due to lags in the system (upper ocean and air temperature did not increase).

    Meehl et al only show that it may be possible for the OHC to increase over short periods while the upper ocean is cooling slightly. And this only if they know all the relavent imputs to their model.

    The model clearly has no relavence to the current situation as the real world thermal expansion data is not consistent with it’s results.

  4. 54
    Ken Lambert says:

    Alex Harvey #51 makes points that I have pondered too:

    Dr Trenberth responded on the **’Trenberth on Tracking…’ SKS thread recently..

    Quote:
    “ENSO involves a redistribution of OHC and losses to the atmosphere in the latter part of El Nino, and gains during La Nina, so this is internal to the climate system, not external (comment 31). The southern ocean is clearly playing a role (comments 48, 49)in taking up heat and mixing it deep, even though the magnitude of the observed warming is small. But the data are fragmentary and unsatisfactory in many respects. Nonetheless, the southern oceans, while playing some role, are not the main place where the heat goes in our model. We have a paper submitted that describes and documents that in more detail so it is premature to go into detail here.”
    Endquote

    When does ENSO become an ‘external’ and not an ‘internal’ forcing of the climate system? El Nino and La Nina cycles are NOT 10 years apart. Dr Trenberth seems to be offering another ‘model’ in his upcoming paper rather than actual observations. We will read it with great interest.

    This is what Dr Trenberth** said on SKS about the ‘Asian sulphates’ explanation for the stasis in surface temperatures:

    Quote
    “There is discussion in the comments of the supposed finding that increasing aerosol (pollution) from China may be the explanation for the stasis in surface temperatures and I do not believe this for a moment. Similarly, Jim Hansen has discussed the role of aerosol as a source of discrepancy. However, the radiation measurements at the top of the atmosphere from satellites (CERES) include all of the aerosol effects, and so they are not extra. They may well be an important ingredient regionally, and I have no doubt they are, but globally they are not the explanation.”
    Endquote

    Dr Hansen accepts that the warming imbalance is about 0.6W/sq.m over the 2005-10 period and his explanation is mainly increased reflective Asian aerosols and Dr Trenberth is sticking to the 0.9W/sq.m+ and his explanation is that we can’t measure the oceans accurately enough to find the ‘missing heat’.

  5. 55
    Greg Wellman says:

    Bob @53. The thermal expansion coefficient of water varies with temperature. For fresh water it’s zero around 4C. For sea water it’s a bit different, but it’s definitely true that water at the temperature of the deep ocean has a lower thermal expansion coefficient than warmer water. Thus a period of time where most of the heat is going deep rather than staying in the surface layer will also be a period of time with a lower rate of thermal expansion of the oceans, even if the total rate of heating is identical.

    Also, the recent (last year or so) decrease in sea level appears to be because an anomalously large amount of water has been transferred to land by rainfall and hasn’t run back off to the sea yet. All those floods (e.g. in Pakistan, Australia, and the US) add up.

  6. 56
    RichardC says:

    Gavin said: “Thus the only way to measure the heat flux into the deep ocean is either to measure the temperature changes there directly (hard), or model the advective and diffusive fluxes at the interface (very hard). – gavin]”

    Measure temperature in the top of the ocean with ARGO, take into account mass changes in ocean water, and measure sea level. Doesn’t that give us deep ocean temperature/heat content/flux?

    [Response: Good point. For this to work, you'd need very accurate freshwater additions, that's still hard, and even then there isn't an exact one-to-one correspondence between temperature and volume (it's close but not exact). - gavin]

  7. 57
    Lars Rosenberg says:

    Bob Irvine #53.
    These references from Meehl et al. may give you more insight into “the real world”:

    Purkey, S. G. & Johnson, G. C. Warming of global abyssal and deep Southern Ocean waters between the 1990s and 2000s: Contributions to global heat and sea level rise budgets. J. Clim. 23, 6336–6351 (2010).

    Song, Y. T. & Colberg, R. Deep ocean warming assessed from altimeters, gravity recovery and climate experiment, in situ measurements, and a non-Boussinesq ocean general circulation model. J. Geophys. Res. 116, C02020 (2011).

  8. 58
    CM says:

    Gavin at #52, re: CO2 last 8,000 years,

    Funny, I cranked through the same 280/260 ppm / 8000 years calculation just the other day to make sense of this misleading graph and discussion at climate4you. (SkepticalScience has had a few things to say about how the graph extends the temperature record into the present. I have a few things to say about how it’s extended into the past, dropping sharply beyond the 11000 ybp end of the EPICA Holocene CO2 record, thus adding to the impression of a CO2/temp mismatch.) Seems to be a popular playground.

  9. 59
    lucien locke says:

    Gavin, I have a very pertinent question regarding data sets of stratified temperature readings from the surface of the oceans to well below 1000 meters of depth, it’s relevance as a tool for temperature gradient analysis, the very large amount of that data being available from all the oceans the U.S. Navy on the high seas have traversed over the years and has it been accessed from the Navy archives? Sorry, poorly worded question, but, I spent 6 years in the U.S.Navy as a Sonar technician and one of our duties was to launch a Expendable Bathythermograph (XBT).
    An electronic device that measures temperature vs depth using a thermistor on a free-falling streamlined weight. The thermistor is connected to an ohm-meter on the ship by a thin copper wire that is spooled out from the sinking weight and from the moving ship. The XBT is now the most widely used instrument for measuring the thermal structure of the upper ocean. Approximately 65,000 are used each year.

    The streamlined weight falls through the water at a constant velocity. So depth can be calculated from fall time with an accuracy of ±2%. Temperature accuracy is ±0.1°C. And, vertical resolution is typically 65 cm. Probes reach to depths of 200 m to 1830 m depending on model.

    This was done as often as 10 times a day throughout a typical cruise, depending on operation status. You probably know all this…but…as back ground for my question, and for the very reason I am asking it, I mention the specs a bit.

    The temperature gradients measured were used to identify thermoclines, an essential piece of information for detection and ranging of potential underwater targeting.

    To rephrase my question, Sir, is there potential use of all of this information for the modeling of surface to depths temperature flow? and secondly, this data set must be enormous based on the number of ships in anti-submarine roles and the number of years the worlds navies have been on the seas. I hate to say this, my participation in this exercise goes back over 40 years ago. There was a lot of data before and certainly alot after…

    [Response: Indeed. This is the raw data for all the estimates of OHC change (at least prior to the Argo float era). - gavin]

  10. 60
    Hank Roberts says:

    >> this data set must be enormous …

    > [Response: Indeed. This is the raw data …

    Perhaps that could be digitized by the CAPCHAs?

    Any librarian-ish estimate of how much exists on paper not digitized?

    Any comment on whether more data points are needed for better results, or are there enough samples now so more won’t change much?

    Wondering if any particular navy’s archive might fill in undersampled areas of space or time, and if they’re being chased down.

  11. 61
    isotopious says:

    The CO2 change (pre industrial) since glacial maximum is around 100 ppm, or about 1ppm per ~200 years. Quite a difference (compared with 1ppm per 400years), so maybe there is more competition from the bio- sphere?, and maybe the robust ocean warming of the last several thousand years is slowing down with time (but is still robust and warming)?

    Indeed, the ice cores capture the CO2 very well, and the whole kerfuffle about leads and lags of 800 years demonstrates that the ocean and the ice are not always in sync with regards to temperature.

    The challenge remains. The ocean has been warming for thousands of years, and NH cooling and advance /retreat of glaciers is just interglacial noise which proves nothing.

    The bulk of the CO2 100ppm change is due to the ocean sink, and is a function of temperature, so during the last 8000 years, we see that the rate of increase in ppm is around halve.

    Therefore, the ocean has been warming on average during the Holocene, albeit at halve the interglacial rate. This is consistent with other lines of evidence such as continued thermal expansion of the oceans.

    [Response: Oh please. The 'It's been warming since the ice age' schtick is getting old. Please take it elsewhere. - gavin]

  12. 62
    Rob Painting says:

    Bob Irvine @ 53 – “Since this study sea level rise has declined further and actually fallen over the last 2 years indicating that thermal expansion is now likely to be negative.”

    Bob, as Greg Wellman has pointed out, the short-term fluctuations in sea level are due to the large exchange of water mass between the oceans and land. La Nina typically causes greater-than-normal rain & snow over land, and a corresponding drop in global sea level, but the last year was a real doozy. See SkS argument 171.

    Now that La Nina is again forming in the tropical Pacific, we might see a “really large pothole in the road to higher seas”, but this effect is only temporary, all that water will eventually end up back in the sea, when we reach a neutral ENSO period or the next El Nino rolls around.

    In the meantime the oceans down to 1500 metres are still warming and expanding (See Von Schuckmann and Le Traon [2011]) and the ice loss from land-based ice has accelerated in the last decade, (See Church [2011]), so it’s hard to see sea level rise coming to a stop anytime soon.

    The Von Schuckmann & Le Traon study is interesting. While other studies measuring down to 700 mtrs show ocean temperatures flatlining, or even decreasing over the short-term (Knox & Douglass [2010]), when Von Schuckmann and Le Traon measure down to 1500 mtrs, they found the oceans are continuing to warm over this short interval. This suggests the oceans can indeed bury heat into deeper layers while the surface layer is cooler-than-normal – much like the modeling of Meehl (2011) indicates.

  13. 63
    Paul Middents says:

    Lucien @ 59 makes a very important point.

    The US Navy submarine force has collected temperature, sound velocity profile and current data for many years. The data from missile submarines operating from 1960 to the present would be particularly useful because the position accuracy would be within a mile. It would include current data from a continuous comparison of the inertial navigation velocity to the electromagnetic log velocity through the water. The data would range in depth for surface to well over 400 feet (how much deeper is still classified).

    The declassification and release of this data would require a congressional level champion like Senator Al Gore who was instrumental in obtaining the submarine under ice data in the 1980′s. The missile submarine data is held by Johns Hopkins Applied Physics Laboratory. They have always had the contract to collect and analyze missile submarine patrol data to provide continuous assurance that the entire deterrent weapon system is performing to specification.

    Paul Middents

  14. 64
    David MacKay says:

    MINOR TYPOS – So what can WE infer about the real world from these tests? First, we can conclude that we ARE looking at the right quantities.

    [Response: Thanks. Fixed. - gavin]

  15. 65
    barn E. rubble says:

    RE: [Response: . . .The damping of the rate of surface warming or the warming in the pipeline isn't anything to do deep ocean heat coming back out. I have no idea where this idea originated, but it is not accurate. - gavin]

    According to Dr. Trenberth deep ocean heat can and will come back out:
    “It can come back quite fast,” he said. “The energy is not lost, and it can come back to haunt us, so to speak, in the future.”

    http://www.dailycamera.com/boulder-county-news/ci_18932226

    [Response: In context, he appears to be talking about changes in OHC related to ENSO variations - this is not the 'deep ocean. However, that is a bit ambiguous. - gavin]

  16. 66
    barn E. rubble says:

    RE: http://www.dailycamera.com/boulder-county-news/ci_18932226

    “[Response: In context, he appears to be talking about changes in OHC related to ENSO variations - this is not the 'deep ocean. . .]”

    The above article’s title:
    Boulder scientists: Climate’s ‘missing heat’ locked deep in the ocean

    And a quote: “The discovery of the heat, which the researchers say is likely locked deep in the ocean, . . .”

    Have I misread this article? Or are they not talking about ‘missing heat’ being in the ‘deep ocean’? IE: beyond 1000m.

    Another quote from the same article: “But Trenberth and his colleagues — including lead author Gerald Meehl — were able to show, using NCAR’s Community Climate System Model, that the excess heat is likely buried deeper than 1,000 feet in the ocean, where researchers now have few reliable temperature gauges.”

    If this is not the ‘deep ocean’ they’re talking about, what is?

    [Response: This was not a very good article in many respects - the Meehl et al paper did not 'discover' any heat, and the framing in terms of the 'travesty' email (which was related to our very incomplete observational capabilities) was clumsy. The particular quote you are talking about is obviously from a longer interview, and the immediate antecedent is a discussion of ENSO:

    The burying of warmer water also corresponds with La Nina weather patterns, which are born from cooler-than-average surface water temperatures in the tropical Pacific. And over the last decade, La Nina conditions have dominated, Trenberth said.

    That the heat is buried in the ocean, and not lost into space, is troublesome, Trenberth said, since the heat energy isn't likely to stay in the ocean forever, perhaps releasing back into the atmosphere during a strong El Nino, when sea surface temperatures in the tropical Pacific are warmer than average.

    "It can come back quite fast," he said. "The energy is not lost, and it can come back to haunt us, so to speak, in the future."

    Now given that we don't have a complete record of what was said, and there is ambiguity about what he is referring to, you can infer what you want - knowing Kevin quite well, I'm pretty confident that he is talking about ENSO and upper ocean variations in OHC related to that, not heat fluxes into the below 700m level. I've explained why heat going below 700m is not likely to 'come back fast', and nothing in this newspaper article changes that. - gavin]

  17. 67
    Alex Harvey says:

    Dear Gavin #51,

    You wrote,
    “…there is no contradiction – both Hansen and Trenberth agree that accurate estimates of the forcings are necessary, and they both agree that the deep ocean is where any remaining imbalance will end up. Nobody is absolutely wedded to a specific number for this.”

    Well, I am sure that even skeptics agree that accurate estimates of the forcings are necessary, and that some amount of heat finds its way to the deep ocean. And it does appear from Trenberth’s statement quoted by Ken Lambert in #54 that he believes Hansen is wrong about aerosol effect.

    Anyhow, I asked another question earlier which you didn’t answer and I’d be most grateful if you would – if you know of course.

    Hansen et al. write,
    “GISS modelE-R … achieves only 60 percent response in 100 years. At least several other climate models used in IPCC (2001, 2007) studies have comparably slow response. Diagnostic studies of the GISS ocean model show that it mixes too efficiently, which would cause its response function to be too slow.”

    Elsewhere he says “many” of the models exhibit this defect.

    Later,
    “Ocean heat uptake during the Argo era agrees well with the intermediate response function (75 percent response in 100 years) and is inconsistent with either the slow or fast response functions.”

    So I am interested to know what the response function is in the model used by Meehl et al. Specifically, is it the 75 percent per 100 years response that Hansen et al. consider realistic?

    Sincerely,
    Alex Harvey

  18. 68
    barn E. rubble says:

    RE:[Response: This was not a very good article in many respects . . . and nothing in this newspaper article changes that. - gavin]

    Well, I now leave as confused (or more so) than I entered . . .

  19. 69
    Rob Waterland says:

    Dear Gavin,

    Are you planning to discuss the new ACPD paper by Hansen et al. (“Earth’s energy imbalance and implications”)? If I understand the paper correctly, ocean observations indicate that current climate models overestimate downward mixing in the oceans, and transport more heat to the deep oceans than in fact occurs. Despite this, climate models generally do a decent job of predicting recent global temperature increases. If the models transport too much heat to the deep oceans but give good performance on surface temperatures, it must follow that the net climate forcing in current models is too large. Since the most uncertain part of the current forcing is aerosol forcing, the Authors propose that true aerosol forcings are considerably more negative than those used in current models.

    [Response: I'm not as convinced as Jim that ocean measurements are out of line with ocean models (see this figure for instance), but of course, there are uncertainties in the aerosol forcings. -gavin]

    I was surprised to read that most models do not use the aerosol forcings that were estimated by IPCC. Why is that?

    [Response: IPCC doesn't produce 'aerosol forcings' - these are a function of the IPCC-sanctioned emissions (though there are reasonable variations around), the aerosol and chemistry model, the microphysics model for the indirect cloud effects, and the radiation code. You can't simply take directly some global mean forcing and say you're done. - gavin]

  20. 70
    Paul S says:

    In regards to #69 – Are there any papers comparing the aerosol forcings (direct and indirect) produced by GCMs against estimates from observations/other modelling exercises.

    Looking at the basic properties of GCMs in the AR4 ensemble I saw that most of the models don’t attempt to produce any indirect effect at all. It seems to me they must underestimate aerosol forcing. The outcome is a curious paradox where some of the lower sensitivity GCMs in the ensemble cast produce some of the fastest rates of warming over the next few decades.

    Is it not probable that the AR4 ensemble projections are slightly too warm in the near-term (at least with respect to this aspect of the climate system. There may be other areas where the models are running too cold)?

    [Response: Yes. Some of the models undoubtedly had too high forcings since they assumed no indirect aerosol effect (though note that some models like GISS-E-R/H did include estimates of that) and obviously that impacts how you should weight them in certain circumstances. But some other models didn't include tropospheric ozone forcing either - so that might cancel to some extent. It could be useful to try and normalise the hindcasts based on late 20th C forcing differences and that might narrow the spread slightly. But note that for short time periods (i.e. less than 20 years or so), most of the variance in trends is due to weather noise, not small differences in net forcing. - gavin]

  21. 71

    A related study is Katsman & van Oldenborgh, Tracing the upper ocean’s “missing heat”, GRL, 38, L14610,, 2011, doi:10.1029/2011GL048417, http://www.knmi.nl/publications/fulltexts/katsman_vanoldenborgh2011.pdf, a correction to a minor computational error is to appear). Just like Palmer et al we find that there are two main causes for decadal heat content fluctuations around the trend in our model (17 transient runs with ECHAM5/MPI-OM): radiation to space (to a large extent connected with decadal ENSO) and heat exchange with the deep ocean (concentrated in the North Atlantic (AMOC) and Southern Ocean). Coming back to the real world, we note that changes in both ENSO and deep-water formation in the Labrador sea are consistent with these findings.

  22. 72
    Brian Dodge says:

    The oceans below ~1000 meters are less than 4 degrees Centigrade. The earth’s average surface (air?) temperature is about 16 degrees centigrade, and the surface layer of the oceans is about 17 degrees C. It would take an enormous number of joules to raise the deep oceans by one degree Centigrade, still less than 5 degrees C. If brought back to the surface, this water wouldn’t actually warm the surface layer and air above it, but would instead absorb less energy. Shouldn’t we be saying that this heat will eventually decrease the cooling/buffering capacity of the oceans, instead of saying this heat will “come back” – out, to haunt us, whatever? (perhaps this contributed some to barn E. rubble’s confusion)

    How much additional infrared is emitted by Arctic ocean water that was formerly perennially ice covered?

  23. 73
    Hank Roberts says:

    > barn E. rubble says:… Well, I now
    > leave as confused (or more so) …

    One day visits aren’t enough to get good answers in unfamiliar territory.
    Maybe a pointer to the ‘elevator speeches’ condensed info would’ve helped.

  24. 74
    R. Gates says:

    Gavin said: Most heat transport into the deep ocean will occur in the down-welling branches of the overturning circulation, centered in the North Atlantic and the Southern Oceans. Diffusive fluxes in the rest of the ocean will be much smaller.”

    ——–

    This is always what I assumed to be the case given the massive amount of water transported downward in these regions. Do you have a few good references that you’d recommend on research done related to the down-welling heat transport in the two regions?

  25. 75
    cd says:

    Is the frequency of low pressure tropical systems a factor relative to polar low pressure systems?

  26. 76
    Bob Irvine says:

    Greg Wellman #55, Rob Painting #62,

    I don’t doubt that cooler water in the deep ocean has a lower expansion coefficient. We are talking here about water below 700m only and the thermal expansion in that body of water is not significantly less than the ocean as a whole.

    Lars Rosenberg #57

    Here is a quote from Song & Colberg 2011
    ” deep ocean warming below 700 m might have contributed 1.1 mm/yr to the global mean SLR or one‐third of the altimeter‐observed rate of 3.11 ± 0.6 mm/yr over 1993–2008.” In other words the ocean below 700m is capable of considerable thermal expansion assuming S & C are correct.

    The real world data, Cazenove & Llovel 2009, shows aprox. 1.3mm/yr thermal expansion from 1993 to 2003 followed by a significant drop to 0.25+-0.8mm/yr from 2003 to 2007 and likely to 2011.

    If the reason for the upper ocean hiatus was changes in the flux between the upper and lower ocean then you would expect the thermal expansion component of SLR to fall slightly due to the different expansion coefficients.

    The real world data shows a huge drop in thermal expansion during the period of the cooling of the top 700m. This drop is too big to be explained by the missing heat hiding in the deep ocean.

    The model shows that these inversions can happen but the real world data proves that this is not significant in this case.

  27. 77
    ldavidcooke says:

    Re: 72

    As to re-emission of IR from the surface about 99.96% is now radiated when compared to prior 19th-early 20th century ice coverage. The main balance going into ice melt, wv, wind and radiating from a higher altitude. Generally, the rate of emission is not changed as much as the time required to remove the heat. Hence, rapid ice redevelopment and maintence of the THC flow rate. In the future when there is nearly no permanent ice and virtually all processes become seasonal, surface emission again will be nearly the same rate (say 99.8%) only from a greater surface area. I believe the better question may be; How different will the rate be when the ice melts and the alternate heat flow pathways (evaporation, sublimination) become more prevalent?

    Cheers!
    Dave Cooke

  28. 78

    Gavin – I am glad you noticed my post

    Torpedoing Of The Use Of The Global Average Surface Temperature Trend As The Diagnostic For Global Warming
    http://pielkeclimatesci.wordpress.com/2011/09/20/torpedoing-of-the-use-of-the-global-average-surface-temperature-trend-as-the-diagnostic-for-global-warming/

    We seem to disagree on several points. First, you write

    “The second point is related to a posting by Roger Pielke Sr last week, who claimed that the Meehl et al paper ‘torpedoed’ the use of the surface temperature anomaly as a useful metric of global warming. This is odd in a number of respects. First, the surface temperature records are the longest climate records we have from direct measurements and have been independently replicated by multiple independent groups. I’m not aware of anyone who has ever thought that surface temperatures tell us everything there is to know about climate change, but nonetheless in practical terms global warming has for years been defined as the rise in this metric. It is certainly useful to look at the total heat content anomaly (as best as it can be estimated), but the difficulties in assembling such a metric and extending it back in time more than a few decades preclude it from supplanting the surface temperatures in this respect.”

    However, we now have a robust way to diagnose upper ocean heat content, we should move to that metric, starting in ~2003, as the primary metric to monitor global warming.

    [Response: The idea that there can be only one metric has no basis in anything. Every new stream of information is useful in building up a picture of what is happening - some records have longevity, others have depth, some are regional, some are global. Your desire to dethrone or torpedo the global surface temperature records is merely rhetorical (unless you are seriously suggesting that we stop monitoring the surface temperatures? Surely not!). - gavin]

    Also, NASA, GISS and CRU analyze their data differently, but they have a large overlap in their raw data; see my post

    Erroneous Information In The Report “Procedural Review of EPA’s Greenhouse Gases Endangerment Finding Data Quality Processes”
    http://pielkeclimatesci.wordpress.com/2011/10/05/erroneous-information-in-the-report-procedural-review-of-epas-greenhouse-gases-endangerment-finding-data-quality-processes/

    [Response: More semantics: - the *analyses* of the raw data are independent, and it is easy to show that you get the same basic trend with completely independent subsets of the data. - gavin]

    You write

    “the surface temperature records …. have been independently replicated by multiple independent groups.

    This is not correct.

    [Response: Yes, it actually is. And the Berkeley effort will show it again. - gavin]

    Finally, you write

    “Obviously heat going below 700m must have passed through the upper ocean. However, the notion that Argo could see this is odd. Argo measures temperature, not flux. The net flux into a layer is calculated by looking at the change in temperature. It cannot tell you how much came in at the top and left at the bottom, only how much remained. – gavin]”.

    You are, of course, correct that Argo measures temperatures, but unless you can show the temporal sampling period is too long, or the spatial sampling is too sparse, the downward movement of heat would be seen in positive temperature anomalies as they move towards lower depth. Similarly, if this heat were to re-emerge, we would also see it as the anomalies move upwards.

    [Response: This is a continuous process - not lumps of anomalous heat that can be tracked individually. - gavin]

    Also, if there is large amounts of heat being stored at depth in the ocean, this means that the global annual average surface temperature trend is not sampling this heat. This surface temperature trend would be underestimating global warming.

    [Response: Semantics: You are redefining 'global warming' to something different to what anyone else thinks and then claiming that the standard measure of global warming (as understood by everyone else) is not being properly sampled. I can redefine apple to mean an orange, and then claim that people shouldn't just bite into apples because of the skin. It might make sense logically, but as a method of communicating a fact to an audience, it is woeful. Words do not mean just what *you* say they mean. - gavin]

    Roger

  29. 79

    Gavin –

    [Response: Yes, it actually is. And the Berkeley effort will show it again. - gavin]

    The Berkeley analysis is a more indepedent assessment. We agree on that, and that it supports the GISS/NCDC/CRU trend findings with respect to the mean. This still does not make the GISS/NCDC/CRU independent.

    The issue of why you persist in retaining the surface temperature trend as the primary metric of global warming is a puzzle to me. We, of course, need surface temperatures for a wide variety of other reasons. However, if significant heat is being transported to deeper depths, I assume you would agree that the surface temperature trend would underestimate global warming and influence the calculaiton of “climate sensitivity”. But let us know if you disagree and why.

    [Response: "Climate sensitivity" is classically defined as the change in surface temperature as a response to radiative forcing. It is an equilibrium concept that is almost completely divorced from the flux of heat into the deep ocean. One could define a new concept - "total heat content sensitivity" (in J per W/m2 - odd unit) which would be related to the standard sensitivity, but also to the ocean mixing processes. Given that concept one could attempt to estimate it from observations and diagnose it in models and one could try and make a case that this was somehow more relevant in terms of impacts or vulnerability. All of these things could be done. But, as far as I am aware, none of them have. Thus, the standard climate sensitivity remains the focus of attention. I would suggest that if you want to change that, you should embark on the steps I gave above rather than simply co-opting language and changing standard definitions. So, to directly answer your question, since surface temperature changes define global warming, they cannot underestimate it. If you really mean to say that surface temperature increases don't tell you much about deep ocean heat content changes, then this is of course true. But in that case I'm not sure what point you are trying to make. - gavin]

  30. 80
    Norman Page says:

    What is the best metric for measuring global warming or cooling.? I submit that the Hadley global SST fits the bill as well as anything.The Oceans occupy 70% of the surface and SST’s while not perfect avoid the problems raised by the UHI effect and more importantly they avoid the problem caused by the fact that the land temperature data does not measure the enthalpy of the system which is the really significant number.Since the sea is 100% saturated with H20 the changing temperature is a good relative measure of the change in enthalpy.
    The Hadley data shows warming from 1900- 1940 ,cooling from 1940 – about 1975 and warming from 1975 – 2003. CO2 levels rose steadily during this entire period. There has been no net warming since 1997 – 14 years with CO2 up 7% and no net warming. ( Check the actual data at the Hadley center) Anthropogenic CO2 has some effect but our knowledge of the natural drivers is still so poor that we cannot accurately estimate what the anthropogenic CO2 contribution is. Since 2003 CO2 has risen further and yet a simple regression from 2003 -2011 shows the global temperature trend is negative. This is obviously a short term on which to base predictions but in the context of declining solar activity – to the extent of a possible Dalton or Maunder minimum and the negative phase of the Pacific Decadal Oscillation a global 20 – 30 year cooling spell is more likely than a warming trend.
    These simple empirical observations are a better guide than our current climate models to the immediate future and our lack of knowledge of the system precludes any useful predictions beyond that date.

  31. 81
    mdenison says:

    Gavin,
    Re Greg @28 and your response

    1. I recently read Tim Hall’s science brief (http://www.giss.nasa.gov/research/briefs/hall_03/) and did wonder at the time if this methodology could be used to estimate OHC. Khatiwala S., F. Primeau, and T. Hall, 2009: Reconstruction of the history of anthropogenic CO2 concentrations in the ocean, Nature, 462, 346-349, doi:10.1038/nature08526.

    2. Has anyone tried to set an upper bound on OHC anomaly given what we know about SST the upper 700m and how heat is transported through the ocean?

  32. 82

    Gavin – You write

    “surface temperature changes define global warming”.

    Here is where we have a fundamental disagreement. Global warming is defined by the accumulation of heat in the units of Joules. Surface temperature changes by itself is not heat.

    [Response: I am well aware that temperature is a different quantity than heat, and have no objection to people tracking the accumulation of heat, but 'global warming' is simply not defined in this way. This is not a 'fundamental disagreement', this is simply you redefining the term 'global warming'. For me (and almost anyone else you care to ask) global warming refers to the increase in global surface temperature anomaly. Indeed, 'warmth' is not a pure function of Joules - ice and water at 0 deg C have the same 'warmth', but very different heat contents. The very natural definition of warming is in terms of temperature; when people say that something has warmed, it means that the temperature has risen. You would be much more effective at communicating your scientific points if you used words in ways other people were already used to. - gavin]

  33. 83
    Rob Painting says:

    Bob Irvine @ 76 – a few things:

    - you conveniently neglect the more recent paper I referred you to, Von Schuckmann and Le Traon (2011), which measures from 10-1500 mtrs deep. They observed the oceans are still accumulating heat over the period 2005-2010. So the oceans down to 1500 mtrs can build up heat, but heat in the top 700 mtrs has barely changed. Remember this is “real world data”. So the model simulations in Meehl (2011) aren’t so fanciful after all.

    - the hiatus periods seen in the model simulations is due to the La Nina-like (negative IPO) state. In other words, it’s the shuffling of heat in the upper ocean, between the subsurface layers and the surface, that causes the warm (El Nino-like)/cool(La Nina-like) decadal global surface temperature trends. This has nothing to do with the heat that is going to the very deep ocean – that won’t re-surface for hundreds to thousands of years.

    [Response: Also check out the latest Church et al paper: - gavin]

    - You seem to have misunderstood Song & Colberg (2011) too. They indicate that heat getting to ocean layers below 700 mtrs explains the observed trend in sea level rise over the period 1993-2008. Again – not inconsistent with the modeling.

  34. 84
    Norman Page says:

    Roger – Gavin Doesn’t my suggestion of using the SST data as the basis for climate discussion resolve Roger,s problems and yet maintain the conventional
    measure of warming and cooling.The thermal inertai of the oceans also smooths out short term noise in the system.

  35. 85

    Gavin – This is one reason why we have a different view of this issue. You write

    “Indeed, ‘warmth’ is not a pure function of Joules – ice and water at 0 deg C have the same ‘warmth’, but very different heat contents”.

    They do not have the same “warmth”, just the same temperature. There is more “warmth” with the liquid water. This is not semantics, but basic physics. If we want to properly monitor global warming, it must be in units of heat.

    You are correct that when ” people say that something has warmed, it means that the temperature has risen”. However, when a scientist say that something has warmed, it means that the Joules have increased.

    [Response: We'll just have to agree to disagree then, because I agree with 'people' in this context. Warming means an increase in temperature for almost anybody you ask, and redefining it to mean something different just leads to confusion. And indeed, since I can find no antecedent for 'climate sensitivity' referring to anything else other than the global surface temperature change, I'm pretty confident that most scientists will agree. But regardless of what the common usage is, if you want to be understood clearly, I strongly suggest you define your terms every time you make a statement if you do not want to be misunderstood. For future reference, any time I use the phrase global warming, it is to be understood to refer to the increase in global mean surface temperatures. - gavin]

  36. 86
    Michael Sweet says:

    Dr Pielke at 85,
    In my Chemistry class we define “warming” as a temperature increase. If the Joules increases we say the enthalpy or the energy content has increased. Can you provide a reference for your claim that “when a scientist say that something has warmed, it means that the Joules have increased.” I will change our definations if you can provide an authoritative reference to support your claim. You made a similar argument last week at Skeptical Science. You appear to be trying to redefine Global Warming. What useful purpose is there in making this change?

  37. 87
    Ray Ladbury says:

    Roger,
    I think that one reason for using global surface temperature as the metric is that this is what determines our experience of climate–drought, precipitation, comfort, etc., will all be influenced more by surface temperature than ocean heat content. I rather doubt that the residents of Bastrop County, TX care much what ocean heat content is doing these days.

  38. 88
    Norman Page says:

    @87 The Texas drought is one of the few events which can reasonably reliably be related to climate change ie the current cooling trend.. In the cooling phase of the PDO La Ninas become more frequent and it is this latest La Nina (which looks like it may build up again and continue into next year)which is responsible for the Texas drought. Incidentally it is also a good example of why land temperatures are not the best measure of climate change .(See 80 and 84 above) Although temperatures in Texas have been very high – the enthalpy of the system is less than the temperature alone might suggest because the humidity has been very low for long periods.
    I happen to own a cabin in Bastrop county and I care quite a bit about the OHC and in particular the SOI . The latter is a useful predictor of likely temperatures and humidity in Bastrop county. These lag the SOI by 5 – 7 months.

  39. 89
    Marcus says:

    @88: there is no such thing as a “current cooling trend”. Unless you redefine and re-redefine “warming” and “cooling” long enough :-)

  40. 90
    Alex Harvey says:

    Dear Roger #78,

    You wrote above that it is
    “…correct that Argo measures temperatures, but unless you can show the temporal sampling period is too long, or the spatial sampling is too sparse, the downward movement of heat would be seen in positive temperature anomalies as they move towards lower depth. Similarly, if this heat were to re-emerge, we would also see it as the anomalies move upwards.

    Gavin responded,
    “This is a continuous process – not lumps of anomalous heat that can be tracked individually.”

    As a layperson I find myself somewhat persuaded by both statements. Intuitively, I would expect that if heat was going to the deep ocean, it would indeed be seen by Argo as “lumps” passing through the upper 700m. Could you elaborate on why you believe that Argo should be able to detect the movement of heat into the deep ocean and why you believe that it hasn’t detected it?

    Sincerely,
    Alex Harvey

  41. 91
    Bob Irvine says:

    Rob #83

    My initial question was. ” How do you square the large drop in thermal expansion since 2003 (1.3mm/yr down to 0.25mm/yr according to Cazenove and Llovel 2009) with your belief that energy is continuing to build at the same rate in the oceans? ”

    Your answer was that colder water has a lower expansion coefficient and therefore the same amount of energy would cause less thermal expansion if it were to find it’s way to the deep oceans.

    Schuckmann et al looked at the top 1500m and found warming. This does vindicate the model as you say. The problem is that the expansion coefficient in this region is not different enough from the top 700m to explain the large drop in thermal expansion.

    Song and Colberg support my position when they state that “deep ocean warming below 700m might have contributed 1.1mm/yr to Sea Level Rise …over 1993-2008″. In other words they are saying that the change in expansion coefficient is not significant when compared with the large drop in thermal expansion.

    Kouketsu et al 2011 found something less than 5% of energy entering the ocean is transported below 3000m and this is the only area where the expansion coefficient is small enough to slow SLR significantly.

    Unless you can satisfactorily explain the large drop in thermal expansion of the oceans over the last eight years then the inescapable conclusion is that the earth’s heat content is increasing much more slowly than all the models predict.

    A couple of other points. Song and Colberg delt with the total period 1993-2008 while we are talking about the difference between 1993-2003 and 2003 to the present.

    There have been 5 el ninos and 4 la ninas since the air temperature hiatus started 13 years ago.

  42. 92
    Mal Adapted says:

    I think I understand what Roger is doing here:

    `When I use a word,’ Humpty Dumpty said in rather a scornful tone, `it means just what I choose it to mean — neither more nor less.’

    `The question is,’ said Alice, `whether you can make words mean so many different things.’

    `The question is,’ said Humpty Dumpty, `which is to be master – - that’s all.’

  43. 93
    R. Gates says:

    I’ve enjoyed the discussion related to what is commonly meant by the terms “global warming”, “temperature”, and “heat”. Ultimately, isn’t the issue about the earth’s energy balance and how changes in that balance affects climate? If it is, then in keeping with that, i would think it would be good to stay focused on energy in all forms as it moves and is transferred throughout the atmosphere and oceans. Certainly higher surface temperatures are one way we would see increases in total energy, and the easiest perhaps to grasp for the public, but perhaps not the most important in terms of long term climate change. The heat going into the deeper ocean “heat sink” may turn out to be more important later on.

  44. 94
    Norman Page says:

    @ 89 My original post said “simple regression from 2003 -2011 shows the global temperature trend is negative.”
    This simply states the truth – what don’t you understand?

    [Response: Ah, the 'truth'! And yet this is only the 'truth' because you pick a specific start date and specific temperature series, and is not 'true' if you do anything different. What kind of 'truth' is this, that is so fragile? - gavin]

  45. 95
    Norman Page says:

    @ 94 Response. In 80 and 84 I gave perfectly good scientific reasons for picking SSTs as the best climate indicator. As to 2003 it is the numerical peak of the SST data ( not counting the 1998 El Nino) and the place where the 5 year moving average rolls over.
    All scientific interpretation of satistical analyses depends on first being transparent – that I have been and secondly they must be taken in context – in this case the state of the PDO and the unprecedented decline
    in the solar magnetic field strength. When you do this my conclusions for the next 20 years or so are not fragile. They are sigificantly more robust than any of the Hansen climate model predictions have been over the last decade- both he and Trenberth are desperately looking for the missing heat – Hansen thinks it has something to do with aerosols and Trenberth conveniently dumps it into the deep ocean. ( These are sort of epicycle type theories – to add on to models which are fundamentally flawed – built as they are on assumptions and assignments of forcings and feed backs which are simply wrong- but thats another story entirely.

    [Response: If you think that your predictions are better than anyone else's, you should be willing to put your money where your mouth is. There are a number of people willing to bet on positive decadal trends and if you think it is going to cool on such timescales, you should take them on. There are even Intrade markets on this - and if you think you know better, take on people there. Your scheme, based on what? linear extrapolation from a cheery-picked record?, is very unlikely to be a good prediction, but you should be encouraged to make predictions and assess your hypothesis in the light of what actually happens. - gavin]

  46. 96
    ldavidcooke says:

    RE:88

    Hey Norman,

    Before we go too far off topic can we first revisit the issue of heat transference. I would like to suggest a simple empirical model, beach sand or desert sand. Many who live near one of the coasts in the sub-tropics are very familiar with how hot the sand between the parking and the shore can get, near noon, if you are not wearing something on your feet. It does not matter if the sand is high in shell pieces (CaCO) or simple white silica or even silica heavily stained with FeO. (The basic character should be similar only the depth of measure will change. We also need to keep in mind that though closer to the waters edge more moisture in the sand will change the measures.)

    The point is if you were to measure the heat at the surface the temperature would exceed a comfortable pain limit for most people. However, if you shuffle your feet below the surface till you reach the waters edge the heat it acceptable. What does the depth have to do with the heat, simple the lower mass is “shaded” by the surface “skin layer”, does radiant energy go into the depths, yes. Many a moon lit night buried in warm sand sand can attest to that, though by morning watching the sunrise, other then reducing wind chill the sand to 1 meter offers little warmth.

    The point being the skin layer and or turbidity may offer the greatest control over insolation. It is not until the skin layer achieves parity with the heat content below that the inversion condition dissapates and the daily insolation is released. However, in soils rich in moisture you can break through the inversion layer and release a portion of the entrapped energy.

    We also should account for the issue in that it does not always require the skin layer to heat up under insolation. Some small part of the incoming photonic energy will be disssapated by the disassociation of a water molecule from the surface by increasing its energy level enough for it to “fly off” the surface. Note, this is more prevelant where there is low RH.

    The point being when we are talking of processes involved we need to consider there are multiple paths in heat flow. When discussing Global Warming we are discussing the primary processes here. Sometimes folks get confused as to the participation of various pathways.

    Now that being said. Since 2000 there have been a number of cases in which TX has seen a number of years of both flood and drought. These events have occurred during a El Nino, La Nina and neutral phase without one directly driving the process, even if you associate delay. The primary driver of these conditions appears to be related to long resident Blocking Highs and Cut-Off Lows.

    The most recent events appears to be related to the Southern Jet Stream having a strong un-seasonal northward track across the US. So my question back to you is why this deviation in a weakend La Nina this year and not a strong deviation last year when the La Nina was much stronger and did not diminish in early June as we normally see in the ENSO driven patterns?

    If this is related to AGW can you define the process that causes the changes in the resident pressure centers? (Note, if you can define the cause for the Bermuda and Azores Highs and their movement I believe you may have better insight into the current events.) Again, as this is a bit OT I will end here.

    Cheers!
    Dave Cooke

  47. 97
    Paul S says:

    Norman Page – With some modifications to Gavin’s link here are trends between 1987 and 1996.

    Should we deduce from this that we’ve been in a cooling phase since 1987?

  48. 98
    David Miller says:

    Bob, in 91, says baldly:

    Unless you can satisfactorily explain the large drop in thermal expansion of the oceans over the last eight years then the inescapable conclusion is that the earth’s heat content is increasing much more slowly than all the models predict.

    Bob, there is at least one alternative to this. Water, you know, evaporates from the ocean and falls, sometimes, on land. It doesn’t all run off. A warmer ocean with warmer air above it, transports more water. If the water doesn’t, or can’t (think dams) run off water is effectively removed from the ocean.

    So, logically, your statement is simply incorrect. Interestingly a recent NASA study found just what I was talking about. Joe Romm had a piece on it recently: http://thinkprogress.org/romm/2011/10/02/332364/nasa-rained-so-hard-oceans-fell/

    — David

  49. 99

    Alex Harvey

    Thank you for your question

    “Could you elaborate on why you believe that Argo should be able to detect the movement of heat into the deep ocean and why you believe that it hasn’t detected it?”

    If you look at current data such as from the ECMWF; e.g. see http://www.ecmwf.int/products/forecasts/d/charts/ocean/real_time/xzmaps/

    you can see areas of positive and negative temperature anomalies. Using the entire Argo network, such “lumps” of greater or less than average Joules should be seen in the analyses as one examines all of the profiles.

  50. 100
    MapleLeaf says:

    Bob @91,

    “Unless you can satisfactorily explain the large drop in thermal expansion of the oceans over the last eight years then the inescapable conclusion is that the earth’s heat content is increasing much more slowly than all the models predict.”

    I would strongly caution people against making confident generalizations based on such a short period of time (i.e., 2003-2010), especially when we know that the AR4 simulations would not have “known” a priori that the aerosol loading increased notably in the last 10 years or so, and that because the data display variability 7 years is way too short a time interval to make claims that the models are wrong (see Santer et al. 2011). There is no reason to expect the increase in to be monotonic as skeptics seem to think. Skeptics getting overly excited every time their is a short-term slow down or hiatus got tiring a very long time ago.

    It fascinates me that skeptics continue to be so focused on short-term trends to the point of seriously missing the big picture. Also, it is curious that people (like Roger Snr.) like to nit pick and make grand claims about the meaning of the OHC data since 2003, but they do very little if anything to better understand the mechanisms and processes at play, and do not even use the full depth of Argo data available. It all seems, instead of trying to better understand the science and to advance the science, an attempt by skeptics to caste doubt.

    In contrast, we have scientists like Meehl, Schmidt, Hansen, Katsman, Oldenborgh, Fasullo, Sato, Church, von Shuckmann and Trenberth etc. making a sincere and determined effort to improve our understanding of the climate system. They are the ones advancing the science and our understanding. The “skeptical” scientists not so much, instead they are doing what amounts to a lot of arm waving, cherry picking and obfuscating.

    Hansen et al. (2011, submitted) and Church et al. (2011) are great papers, and do an excellent job of explaining where the science and data are at, and what it all means. We are not off the hook, and BAU when it comes to our GHG emissions is not an option, it never was.


Switch to our mobile site