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The answer is blowing in the wind: The warming went into the deep end

There has been an unusual surge of interest in the climate sensitivity based on the last decade’s worth of temperature measurements, and a lengthy story in the Economist tries to argue that the climate sensitivity may be lower than previously estimated. I think its conclusion is somewhat misguided because it missed some important pieces of information (also see skepticalscience’s take on this story here).

The ocean heat content and the global mean sea level height have marched on.

While the Economist referred to some unpublished work, it missed a new paper by Balmaseda et al. (2013) which provides a more in-depth insight. Balmaseda et al suggest that the recent years may not have much effect on the climate sensitivity after all, and according to their analysis, it is the winds blowing over the oceans that may be responsible for the ‘slow-down’ presented in the Economist.

It is well-known that changes in temperature on decadal time scales are strongly influenced by natural and internal variations, and should not be confused with a long-term trend (Easterling and Wehner, 2009;Foster and Rahmstorf, 2011).

An intensification of the trades has affected surface ocean currents called the subtropical gyres, and these changes have resulted in a predominance of the La Nina state. The La Nina phase is associated with a lower global mean temperature than usual.

Balmaseda et al’s results also suggested that a negative phase of the pacific decadal oscillation (PDO) may have made an imprint on the most recent years. In addition, they found that the deep ocean has warmed over the recent years, while the upper 300m of the oceans have ‘stabilised’.

The oceans can be compared to a battery that needs to be recharged after going flat. After the powerful 1997-98 El Nino, heat flowed out of the tropical oceans in order to heat the atmosphere (evaporative cooling) and the higher latitudes. The warming resumed after the ‘deflation’, but something happened after 1998: since then, the warming has involved the deep ocean to a much greater extent. A weakening of the Atlantic meridional overturning circulation (MOC) may have played a role in the deep ocean warming.

The recent changes in these decade-scale variations appear to have masked the real accumulation of heat on Earth.

The new knowledge from this paper, the way I read it, is the revelation of the role of winds for vertical mixing/diffusion of heat in a new analysis of the world oceans. Their results were derived through a set of different experiments testing the sensitivity to various assumptions and choices made for data inclusion and the ocean model assimilation set-up.

The analysis involved a brand new ocean analysis (ORAS4; Balmaseda et al., 2013) based on an optimal use of observations, data assimilation, and an ocean model forced with state-of-the-art description of the atmosphere (reanalyses).

By running a set of different experiments with the ocean model, including different conditions, such as surface winds and different types of data, they explored which influence the different conditions have on their final conclusion.

The finding that the winds play a role for the state of the warming may not be surprising to oceanographers, although it may not necessarily be the first thing a meteorologist may consider.

Other related discussions: OSS


References

  1. M.A. Balmaseda, K.E. Trenberth, and E. Källén, "Distinctive climate signals in reanalysis of global ocean heat content", Geophysical Research Letters, vol. 40, pp. 1754-1759, 2013. http://dx.doi.org/10.1002/grl.50382
  2. D.R. Easterling, and M.F. Wehner, "Is the climate warming or cooling?", Geophysical Research Letters, vol. 36, 2009. http://dx.doi.org/10.1029/2009GL037810
  3. G. Foster, and S. Rahmstorf, "Global temperature evolution 1979–2010", Environ. Res. Lett., vol. 6, pp. 044022, 2011. http://dx.doi.org/10.1088/1748-9326/6/4/044022
  4. M.A. Balmaseda, K. Mogensen, and A.T. Weaver, "Evaluation of the ECMWF ocean reanalysis system ORAS4", Q.J.R. Meteorol. Soc., vol. 139, pp. 1132-1161, 2012. http://dx.doi.org/10.1002/qj.2063

206 Responses to “The answer is blowing in the wind: The warming went into the deep end”

  1. 51
    Titus says:

    R Gates @47

    No problem understanding convection moving around in any direction; circles included:). Advection is a new word for me and one of the reasons that sparked my initial thoughts to comment.

    Jeremy Grim @48.

    There are loads of folks of all persuasions that question evolution. There’s a great new read by an atheist philosopher by the name of Thomas Nagel called Mind and Cosmos. Check it out.

  2. 52
    Lawrence McLean says:

    #19, Rob Painting, would you give me any sort credit for this comment? (http://www.realclimate.org/?comments_popup=8842#comment-216195) it is comment #30 by the way. Cheers :)

  3. 53
    Patrick says:

    @51 Very sorry, but the impression @48 that wannabe skeptics are often “numbered with those who refuse to accept evolution” is well-founded.
    Nothing in biology makes sense without evolution. All evolution–as we have known it–is co-evolution. Add to that epigenetics, developmental placticity etc. Probably it’s the words themselves–reductionism/emergentism etc., and the old categories–that are in the way. There is probably less real disagreement than it seems, and more merely semantic exclusivism.

    Cladistics, for a salutary/solutinary instance, has been not just a next way of categorizing things, but a next way of understanding them. It’s like a flow chart, a view of process.

    Degrees of consciousness come with degrees of complexity. Scopes-trial mind is still with us. No deus-ex-machina is required in order to exit from it. All that is required is a full(er) appreciation of complexity.

    It has always seemed to me that the greatness of Darwin had to do with the fact that he was trained in geology. So he was used to imagining things (sic) on the geological timescale. But he made the step of thinking biology on that scale. The key to ‘getting’ the co-evolution not only in the complexity of the eye, but in consciousness itself, may lie with the imagination of time–a sense (of timescale) that is being stretched right now. Ditto, maybe, for ‘getting’ some issues in climate science–as far as the public or cultural consciousness goes.

  4. 54
    Patrick says:

    Somewhere Darwin says: an obstacle to accepting evolution will be the difficulty the mind has to grasp vast stretches of time. (I have lost the exact reference.) One could say the same thing about some issues in climate science.

  5. 55

    Regarding DocMartyn’s comment. He tried pushing this discrepancy of heat between the different layers on the Climate Etc blog last month.

    This was my response at the time:
    http://judithcurry.com/2013/03/29/has-trenberth-found-the-missing-heat/#comment-307147

    I really think that the discrepancy is in the measurement noise, 89 vs 100 is a 10% error if the heat is asymptotically equipartioned between the layers. Yet skeptics such as DocMartyn will continue to scream that this noise is the signal.

  6. 56
    SecularAnimist says:

    Titus wrote: “There are loads of folks of all persuasions that question evolution. There’s a great new read by an atheist philosopher by the name of Thomas Nagel called Mind and Cosmos.”

    Nagel’s argument is that reductionist materialism cannot account for the existence of mind. He does not in any way question biological evolution.

  7. 57
    Paul S says:

    Web,

    DocMartyn’s comment appears to be simply factually inaccurate. The blue line in his image represents 0-700m, not 300-700m as he suggests.

  8. 58
    Toby Thaler says:

    #50 David Benson–The scenario you link to does not and cannot contain “evidence of the consequences.” There is no such thing as “future evidence”. A major reason it is so difficult to get policy movement is the large amount of uncertainty in the projections of future events based on current trends (“Past Performance is Not Necessarily Indicative of Future Results”). When “warmists” cite such scenarios as if they are “evidence” or “certainties” our credibility is diminished.

    I do wish to be clear–I strongly advocate for scientists to speak out about the range of likely consequences flowing from various policy paths. Certainty is not needed to know that some actions, like “business as usual”, are highly likely to have far more unpleasant consequences than other scenarios. I believe scientists have a moral obligation to speak out about those possibilities based on their knowledge and expertise. It takes courage, and I appreciate what I’ve seen from RC authors. We need an order of magnitude more.

  9. 59
    Steve Fitzpatrick says:

    Based on updated heat content data from Levitus et al (http://www.nodc.noaa.gov/OC5/3M_HEAT_CONTENT/) the heat accumulated for 0 to 2000 meters from ~1990 to present corresponds to a global average energy imbalance of a bit under 0.45 watt per square meter (assuming I have done my arithmetic correctly). The rate of increase in heat for 0-2000 meters looks to be fairly constant over that period, with only modest variation. Does Balmaseda et al present data which supports a increase in heat uptake over the last decade compared to Levitus et al? (I would look for myself, but the article is pay-walled.)

  10. 60
    Hank Roberts says:

    http://scienceblogs.com/evolutionblog/2013/03/19/thomas-nagel-needs-better-defenders/

    Pointing out Nagel, like many climate deniers, bases his thinking on this:
    “… it is prima facie self-evident …”
    as lampooned here: http://jules-klimaat.blogspot.com/2013/04/zonder-titel.html

  11. 61
    SecularAnimist says:

    Hank, this is not the place for an exegesis of Nagel’s views, but in fairness I would point out that in the very brief passage from Nagel’s book quoted at ScienceBlogs by Jason Rosenhouse (who begins by acknowledging that he has not even read Nagel’s book), the phrase “it is prima facie self-evident” does not appear.

    What Nagel actually wrote was “prima facie highly implausible“. And of course, modern science tells us a great many things that seem “highly implausible” even to people who know them to be true.

    Nagel also describes the view he is discussing as “the untutored reaction of incredulity” and a “naive response” — which sounds to me much like the language used by yourself and others to criticize climate change deniers who reject science that they find “implausible” thanks to their “untutored incredulity”.

  12. 62
    Icarus says:

    GISS forcing data shows the net climate forcing levelling off since about 2000, yet some argue (based on ocean heat content data) that global warming has actually accelerated in this period. It seems to me that there is a contradiction here (I know about warming ‘in the pipeline’ but that can’t really explain acceleration). What is the most likely explanation for the apparent contradiction?

    [Response: Recent trends in forcing are quite uncertain since we don’t have good aerosol data (either emissions or concentrations) so I am doubtful that there can be a strong contradiction here (since that would require more accurate forcings). – gavin]

  13. 63
    Ed Barbar says:

    If winds are important to earth’s sources and sinks of energy, wouldn’t it be bad then to slow them down with Windmills?

    I’m also concerned about Solar power, especially the potential for very efficient panels. All those panels will convert heat into electricity, thereby cooling the locations at which they are installed, and then send it around to locations, where the electricity will be turned back into heat. Especially if this is used for heating, it could take high heat areas and cool them down, but heat up potentially cooler places. This would increase the mean temperature of the earth, a very bad thing.

  14. 64
    Paul S says:

    DocMartyn’s comment appears to be simply factually inaccurate. The blue line in his image represents 0-700m, not 300-700m as he suggests.

    Hmm… I think I might have misread what he was trying to show (?) In any case it’s not really a problem for 300-700m to show a greater proportional increase in energy content than 0-300m.

  15. 65
    sidd says:

    Mr. Steve Fitzpatrick writes on the 29th of April, 2013 at 12:37 PM:

    Re: Levitus(2012) compared to Balmaseda(2013)

    I think they are consistent. Please see

    http://membrane.com/sidd/balmaseda-2013.html

    for a comparison and comment.

    sidd

  16. 66
    BillS says:

    Convection, conduction, advection got me thinking about sitting in a bathtub of slightly warm water and a warm bathroom. Let the water stabilize (no moving around) and then slowly turn on the hot water (or the cold) and let your feet and your seat tell you what’s going on. If you have a heat lamp in the room then radiation comes into play.

    Thankfully, others have had similar thoughts: http://blowers.chee.arizona.edu/cooking/heat/convection.html

  17. 67
    Steve Fish says:

    Re- Comment by Ed Barbar — 29 Apr 2013 @ 3:33 PM

    Ed, you need to think this through a little more. Without any numbers, consider that a forest interferes with the wind. Is this a problem?

    Photovoltaic solar panels remove something less than 20% of the energy of visible light as electricity, but they have a fairly low albedo so that the overall effect is some local warming. Consider that trees also have a low albedo, so should we not be trying to regenerate the large areas of forest that have been decimated?

    Steve

  18. 68
    Pierre-Normand says:

    @ Icarus, 29 Apr 2013 at 3:28 PM

    This apparent contradiction also bothered me for a while. Let me add something to what Gavin already said. Informal talk about “global warming” is liable to confuse two distinct phenomena. “Global warming” most commonly refers to a positive rate of change in global average surface temperatures. Lets label this ‘SGW’. But “global warming” also can refer to the positive rate of energy gain by the whole troposphere/oceans system that results from a radiative imbalance at the top of the atmosphere. Lets label this different phenomenon ‘RGW’ (‘R’ for radiative).
    Now, it is important to note that radiative imbalance is a function of both radiative forcing and surface temperature. When there occurs a positive step change in forcing, surface temperatures eventually increase until enough heat escape from the surface and into space through the 8-14 µm ‘atmospheric window’ and the radiative balance is thereby restored. This means that changes in surface temperatures and changes in forcing both can cause variations in the rate of RGW. If internal variability, such as the surface cooling associated with La Nina episodes, causes an increase in RGW, this means that a temporary reduction in SGW can cause an increase in RGW, or, paradoxically, ‘global cooling’ can cause ‘global warming’. But the paradox merely stems from a failure to distinguish ‘surface global warming’ from ‘radiative global warming’. Such considerations, together with the uncertainty about total forcing mentioned by Gavin, pretty much take care of the paradox.

  19. 69

    Web,

    DocMartyn’s comment appears to be simply factually inaccurate. The blue line in his image represents 0-700m, not 300-700m as he suggests.

    He shows the intervals graphically but his math shown on the side of the figure does take into account the differential and not cumulative.

    I don’t think it matters because it is likely systemic noise. The ratio of 7.5 heat units over 700 meters versus 3 heat units over 300 meters is 7.5/3*300/700=1.07, which is only 7% higher than top-down diffusional flow would predict.

    I responded right away to DocMartyn, because I had recently modeled the OHC profiles and found that my model fits were also not as “perfect” as I would like to see.
    The 300-700m interval is receiving slightly more heat than the 0-300m interval assuming top-down diffusion and proportional volumes.

    If it is not measurement noise or errors then perhaps it is a bottom-up flow that pushes slightly more heat in the lower interval first than the upper. This possibility has been mentioned elsewhere by commenters in this thread.

    Generally speaking, the march of entropy demands that heat is dispersed over available states in the system, and any transient solution to the heat equation should approximate this proportional partitioning.

    My issue again is that DocMartyn is nit-picking the details without seeing the general agreement. We will likely see this error diminish with time.

  20. 70
    omeje oblak says:

    I wonder if testing their “little grey cells” would be useful by asking these clever chappies “If average surface temperatures are close to 14ºC and the earth’s core has a temperature in excess of 5,000ºC, how is it that the deep oceans remain so dreadfully cold?

  21. 71
    Ray Ladbury says:

    Ed Barbar,
    You’re from Texas, aren’t you?

  22. 72
    Steve Fitzpatrick says:

    sidd #65,

    Thanks. It looks to me like the Levitus et al data shows a continuous increast from 1990, while Balmaseda et al show a substantial drop post post 1990 (Pinatubo?) and later rapid recovery. Why do you think the two are consistent with each other?

  23. 73

    In regards to Pierre-Normand’s distinguishing between the SGW and RGW signals, I would think that the GW signal can be split according to a Ocean above surface measure and a Land-only measure (LGW). Then the average can be pro-rated according to the 70/30 split between ocean and land. If half of the excess heat is being absorbed by the ocean according to the OHC signal, then the actual GW would be as follows
    GW = 0.7 * (1/2*LGW) + 0.3*LGW = 0.65*LGW

    And this is pretty much what we see. The GISS measure of global temperature anomaly is about 2/3 of the BEST land-only temperature anomaly. GISS shows about a 0.8C anomaly, while BEST is about 1.2C over the last 100 years. This seems like a very intuitive take on what is happening with regard to the role of OHC.

  24. 74

    This is in regard to Pierre-Normand’s distinguishing between the SGW and RGW signals. I would suggest that the GW signal be split according to a Ocean above surface measure and a Land-only measure (LGW). Then we can weight the measure according to the 70/30 split between ocean and land. So if half of the excess heat is being absorbed by the ocean according to the OHC signal, then the actual GW would be as follows
    GW = 0.7 * (1/2*LGW) + 0.3*LGW = 0.65*LGW

    And this approximately reflects what we see. The GISS or HADCRUT measure of global temperature anomaly is about 2/3 of the BEST land-only temperature anomaly. The GISS shows about a 0.8C anomaly, while BEST is about 1.2C over the last 100 years. This seems like a very intuitive take on what is happening with regard to the role of OHC.

  25. 75
    Matthew L says:

    I am probably missing something fundamental here, so bear with me!

    What is the relationship between the temperature of the ocean surface and the temperature of the air above it?

    The huge total thermal capacity of the oceans, which is about a million times greater than the total thermal capacity of the atmosphere, means they can absorb a lot of extra energy with only a very slight rise in temperature. If the temperature of the oceans only rises very slightly in response to TOA forcing surely this limits how much the atmosphere can rise in temperature in response to the same TOA imbalance? Is it possible for the oceans to be perpetually cooler than the air above them? Is there not a continual trend towards equilibrium with excess atmospheric heat that might otherwise cause a rise in the difference in temperatures between air and ocean finding its way into the oceans?

    In other words surely it is not possible, in the long term, for the atmosphere to rise in temperature any faster than the ocean?

    I am not saying that anybody is suggesting that, but if the IPCC is projecting a +3c rise in atmospheric temperatures then they must be projecting a +3c rise in ocean temperatures too. Is there enough of a TOA energy imbalance to provide that kind of heat input into the oceans?

  26. 76
    sidd says:

    Re: Levitus, Balmaseda

    The peak and dip around 1990 from pinatubo is present as a smaller feature in Levitus than in Balmaseda. The latter shows a drop od 4e22J (0-2000m) while Levitus is perhaps half that. But given that the error bars on Levitus are about 2e22 J and say 1e22 J in Balmaseda. I think the two are not so far apart.

    sidd

  27. 77
    Titus says:

    Firstly my apology for earlier taking this thread off topic with evolution. It was only meant as a direct observation to post #48 who meantioned it. Nagel’s book needs to be read before any reviews are considered. A must read for anybody with interest in linking biology and consciousness.

    Oblak @70. My little ‘laymen brain’ cells tell me that it’s a small amount of heat that comes from the core as geothermal energy. Most energy is converted to mechanical movements in plate tectonics and the like. Interested to know if this is still considered by the mainstream.

  28. 78
    Phil Scadden says:

    Ed Barbar, in addition to Steve’s point, conservation of energy applies. Moving energy from one part of the earth’s surface to another cannot increase mean surface temperature.

    [Response: not quite. Transfers of heat for instance from tropics to poles will affect local processes differently and change factors (like ice cover, clouds or water vapor amounts) that impact the global energy balance in ways that don’t necessarily cancel in the global mean. As far we can tell though, these are small net effects. – gavin

  29. 79
    Titus says:

    Firstly my apology for earlier taking this thread off topic with evolution. It was only meant as a direct observation to post #48 who mentioned it. Nagel’s book needs to be read before any reviews are considered. A must read for anybody with interest in linking biology and consciousness.

    Oblak @70. My little ‘laymen brain’ cells tell me that it’s a small amount of heat that comes from the core as geothermal energy. Most energy is converted to mechanical movements in plate tectonics and the like. Interested to know if this is still considered by the mainstream.

    [Response: The amount of heat that gets to the surface of the earth from below is of order 50 milliwatts/m^2 In contast, the mean heating of the surface from above (from the sun) is 340 watts/m^2. Geothermal heat is totally neglible compared with solar heat (except during a volcanic event, and then only when you are on top of the volcano!). –eric]

  30. 80
    MARodger says:

    Titus @79 & omeje oblak @70.

    The question asking why oceans are so cold was from my comment @12. I assume @70 was asking for an answer but the point of the question was to present an undeniable truth to denialists that would gets them thinking how ridiculous their understanding of ocean heating actually is.

    If it is 5,000ºC below the oceans and on average 14ºC above, the cold oceans must be continually warming. The Earth’s crust insulates below reducing the warming from that source to a trickle (although still significant over geological time). And the oceans insulate themselves from the full heat of atmosphere & solar radiation because cold water sinks down away from the warmth at the surface. That cold water comes from the poles and that is why the oceans are so cold.
    With the poles warming, that cold polar water is in shorter supply. With global warming, the warming of that cold polar water, a process that hasn’t just started because of AGW, a process that prevents the oceans from freezing over during ice ages – that warming of that cold water from the poles will increase. But the bottom of the ocean will remain nigh on freezing until sea ice disappears year-round at both poles.

  31. 81
    Martin Vermeer says:

    Matthew L. #75:

    The huge total thermal capacity of the oceans, which is about a million times greater than the total thermal capacity of the atmosphere, …

    Eh, no. More like hundreds of times greater. Consider that the atmosphere is roughly equivalent to 10 m of water, while the oceans are on average 2000 m deep. That’s 200x (bear with me, order-of-magnitude wise).

    Consider also that the ocean is not a single big bucket of water. It has structure. Most exchange of heat between atmosphere and ocean on the relevant time scale concerns the surface layer, some 200 m or so. Getting heat from the atmosphere to the deep ocean takes on the order of a thousand years, the time scale of ocean overturning. See this.

  32. 82
    Steve Fitzpatrick says:

    Martin Vermeer# 81,
    The heat capacity of the atmosphere is closer to 3.5 meters of ocean , though the exact value depends on how much latent heat is considered. The average depth of the ocean is close to 4 Km not 2 Km. So total ocean heat capacity is on the order of 1,200 times the atmosphere above it. Taking the heat capacity of the atmosphere above land into consideration, the ocean’s heat capacity falls to about 800 times larger than the total atmosphere.

  33. 83
    Pete Dunkelberg says:

    Martin @ 81, “Getting heat from the atmosphere to the deep ocean takes on the order of….”

    Let’s try minutes, and work back from there a little if you wish.
    Fully equilibrating the deep ocean takes a long time. But the vertical currents that are part of the THC evidently go as fast as the horizontal currents, else how would it all work?

  34. 84
    Paul S says:

    Phil Scadden #78 – Further to Gavin’s points you could also increase global average temperature by shifting energy to areas with more surrounding land, such as NH mid-to-high latitudes. Land areas warm faster than ocean areas, which means you get a warming uptick in the land-dominated region, without a similar-size cooling in the ocean-dominated region energy has transferred from, so the overall average shows a warming.

    You can see this demonstrated in the shape of the annual cycle for global average temperature, which peaks in Northern Hemisphere summer despite the Earth receiving considerably more energy from the Sun during the Southern Hemisphere summer. The cycle is dominated by fast warming and cooling of NH land in response to seasonal insolation.

    This is a short term effect of course. In order to keep this type of warming going you would have to perpetually shift more and more energy into the land-dominated region, which is impractical in the long-run.

  35. 85
    Matthew L says:

    Thanks for the clarification on ocean heat capacity. I would be interested if anybody has a view about whether a +3c rise in atmospheric temperatures in response to a doubling of CO2 also means a rise of +3c in ocean temperatures?

    Or does it mean a rise of +3c only in atmospheric temperatures? In which case how can that happen? Surely if the oceans are increasingly “cooler” relative to the atmosphere then heat will find its way from warmer to colder somehow?

  36. 86
    Paul S says:

    Matthew L,

    Perhaps someone can provide a more technical answer but comparing atmospheric and ocean temperature as like-for-like information is not a simple matter due to differences in pressure and density of the different materials. I guess the basic answer would be that ocean temperatures will tend towards values in balance with atmospheric temperatures, but that doesn’t necessarily mean a measured 3ºC change in both.

    Just remembered I stumbled upon a relevant chapter from a textbook a few days ago, it might provide some better insight.

  37. 87
    Ric Merritt says:

    I’ve always figured that sea level rise is the simplest diagnostic of global warming overall, because most added energy will soon show up in the oceans, and the same is true of net melting of land ice. (With some allowance for short-term exchanges with other reservoirs in both cases.)

    But the reversal of sign of thermal expansion of water at ~4 deg C is a complicating factor. Is this negligible in the big story, given the amount of added heat going into water already warm enough to actually expand?

  38. 88
    Steve Fitzpatrick says:

    #85 Matthew L,
    Those are complicated questions. The temperature at great depth has a lower limit which is set by the temperature at which ocean water freezes (it can never be colder than that). Cold water is more dense than warm water (although salt concentration also has an influence), so very cold water at high latitudes tends to sink, especially in winter, and flows across the ocean bottom worldwide; the ocean at great depth is therefore everywhere cold and fairly uniform in temperature. Cold, deep water is (on average) continuously upwelling at lower latitudes, though the rate of upwelling does vary with region. Warming from the surface takes place mainly due to ‘eddy driven down-mixing’ where turbulence generated by the shear imposed by horizontal currents, both surface flows and at different depths) leads to mixing of shallower, warmer surface water with deeper cold water. In the absence of shear, the very little heat would make its way downward, because lower density warm surface water floats on colder (denser) deep water. The combination of cold upwelling deep water and eddy driven down-mixing of surface heat leads to a fairly rapid drop in water temperature with depth, along a profile which is called the ‘thermocline’. Net warming at the ocean surface in the thin (20 to 200 meters) well mixed layer, which is where the ‘ocean surface temperature’ is measured, must of course lead to a change in the shape of the thermocline over time, with the greatest warming in the well mixed layer and less warming at increasing depth. How total total heat accumulation evolves over time, and how much warming will take place at different depths over time is not completely understood. In any case, very significant warming at great depth (eg. >1C warming at 1-2 Km or greater) in response to a 3C warmer surface would likely take place only on very long time scales (hundreds of years or more). The sinking of cold water at high latitudes and upwelling at lower latitudes is called the ‘thermohaline circulation’.

    There are lots of good sources of information on physical oceanography on the web if you look.

  39. 89
    Anonymous Coward says:

    And further still to #84 and #78, the energy radiated from a spherical blackbody isn’t proportional to the average surface temperature to begin with. You’d need to raise temperatures to the fourth power before averaging.
    The smaller the temperature gradients, the less energy is radiated from the surface (assuming a constant average surface temperature).
    Because the gradients on Earth aren’t that large to begin, this is a relatively small effect but when you’re concerned with mere fractions of a degree, it’s something else to take into account.

  40. 90
    sidd says:

    Re:reversal of sign of thermal expansion of water at ~4 deg C

    I think this applies to fresh water, not saline water in the ocean.

    sidd

  41. 91
    Rob Painting says:

    I would be interested if anybody has a view about whether a +3c rise in atmospheric temperatures in response to a doubling of CO2 also means a rise of +3c in ocean temperatures?

    No. You did not understand the heat capacity comment that you made earlier. The same amount of energy going into the ocean will result in a smaller change in temperature than would be the case if that energy was going into the atmosphere. This is because of the ocean’s larger heat capacity – the greater mass means there are more molecules to divvy the heat up into. That’s why the absolute changes in ocean temperature are smaller than surface temperatures.

    An analogy: Two villages, but one village’s population is a thousand times larger than the other. Supplying the same amount of food to the larger village, that the small village typically consumes, will result in starvation. Supplying the same amount of food to the small village, that the larger village typically consumes, will result in oversupply and waste.

  42. 92
    Pete Dunkelberg says:

    Titus, you might be interested to know that possible heating of our environment from deep within the earth was one of the first things to be investigated when the question of how the earth gets its temperature was first scientifically studied.

    About T. Nagel and the matter of biology, consciousness and everything, a few notes. It’s very good to wrestle with these ideas, and to do so with enthusiasm. Nagel’s ideas are not the only ones though by a good ways.
    A couple of reviews by philosophers:
    http://www.bostonreview.net/BR37.6/elliott_sober_thomas_nagel_mind_cosmos.php
    http://www.thenation.com/article/170334/do-you-only-have-brain-thomas-nagel?page=full

    Reviews aside, there is much more to read and think about in areas that Nagel touches on. I’m thinking of studies of consciousness and biology and especially evolution. As Nagel admits, his science comes from reading popular works. It is a strong inference that he is influenced by creationism, especially the ID version. In fact he very favorably reviewed a book by a leading IDist named Meyer. The book has “signature” in the title. This puts Nagel in “Dunning-Kruger” territory regarding evoloution and related matters. If you are interested in evolution, study it! Learn the real thing before accepting criticisms from someone who doesn’t get it himself.

    For a couple helpful books on biology and consciousness:

    _Braintrust_ by Patricia Churchland
    well followed by … umm I forget the title but EO Wilson’s latest book – it’s on aspects of group selection but that’s not in the title as I recall. You will see though that group selection has much relevance to evolution of morality, a big topic of Nagel’s.
    I hope Nagel will just be the start of your explorations. As in in other aspects of life, your first love may not be your last but it is good to have one all the same.

  43. 93
    SecularAnimist says:

    Pete Dunkelberg wrote: “About T. Nagel and the matter of biology, consciousness and everything …”

    What I find interesting about such discussions is that in most cases, the word “consciousness” is never really defined.

    And oddly enough, the philosopher types seem to be more concerned with defining exactly what they mean by “consciousness” than do the scientist types.

    I’ve seen biologists go on and on making pronouncements about “consciousness” but when pressed to define that term, they can offer (at best) only vague and nebulous notions that they would never, EVER accept as the basis for serious discussion of questions in biology.

    The same applies to such terms as “mind” and “intelligence” which people often bandy about as though they knew exactly what they meant by them, which they don’t.

    I mean really, there are still scientists who question whether “consciousness”, “mind” and/or “intelligence” even exist in other primate species, let alone other vertebrate species, let alone other species further removed from us paradigmatically “conscious” human beings. (Is an ant colony “conscious”? After all, the individual ants communicate and coordinate their activities with complex chemical signals, not unlike the neurons in our brains, so why should that communication not give rise to “consciousness”?)

    Others question (more reasonably in my opinion) whether and how we might even be capable of recognizing these capacities in other species. Nagel’s famous 1974 essay, “What Is It Like To Be A Bat?” touched on this question, and Carl Sagan wrote an essay on what it might be like to be a tick.

    How can we possibly answer such questions? If we cannot answer them, then where do we get off making general statements about “consciousness”? And until we can at least approach those questions, we are a long, LONG way away from answering much more challenging questions about the nature, arising and role of “mind” or “consciousness” or “awareness” or “intelligence” in Nature.

  44. 94
    Steve Fitzpatrick says:

    #90 sidd,

    Yes, the rate of expansion per degree falls in seawater at lower temperature but does not reverse. The rate of expansion at 5C is only about 40% as large as at 25C. So warming at greater (colder) depth causes less expansion than the same degree of warming near the surface. (see: http://www-pord.ucsd.edu/~ltalley/sio210/DPO/TALLEY_9780750645522_chapter3.pdf pg40)

  45. 95
    Bob Loblaw says:

    Matthew L (April 30, 12:21) “What is the relationship between the temperature of the ocean surface and the temperature of the air above it? “

    Not sure that anyone has answered this to you satisfaction yet. There isn’t a simple answer in the sense of a single equation, but I can describe some of the principles,

    To begin, there are really three temperatures we need to think about – not two. Those three are air temperature, ocean temperature, and surface temperature. The distinction arises because the surface isn’t actually air or ocean – it is the boundary between the two. Also, neither air nor ocean temperature are uniform as you move away from the surface – each will have a gradient in temperature, dependent on the various fluxes of energy.

    Nonetheless, when we talk air temperature (the full term you will sometimes encounter is “surface air temperature) we are talking about a short distance above the surface (usually about 1.5m over land) – to distinguish it from air temperature at higher altitudes – and for ocean temperature (again, “ocean surface temperature” is the term), we are talking about the ocean close to the surface.

    At the surface, the ocean temperature and air temperature will match, and we have “surface temperature”. How this links to the temperatues above and below the surface is where life gets more complicated. One approach is called the “surface energy balance” approach, which is based on the idea that the surface has no thickness, so it has no mass, so it can’t store energy. Since it can’t store energy, the sum of all energy fluxes must cancel (conservation of energy). The major energy fluxes are:

    – input of solar radiation (down from the atmosphere)
    – input of IR radiation (down from the atmosphere)
    – reflection of solar radiation (up towards the atmosphere)
    – emission of IR radiation (up towards the atmosphere)
    (These four make up the net radiation input)

    – loss of thermal energy to the atmosphere
    – loss of water vapour to the atmosphere (the energy lost is the energy required to evaporate the water)
    (These two are convective/turbulent energy transfers related to atmospheric motion)

    – loss of thermal energy down into the ocean (also convective/turbulent mixing)

    I have ignored conduction (very small compared to turbulent mixing. Would be an issue on land where conduction into soil replaces convection), and the fact that solar radiation can penetrate some distance into water (not so much an issue on land). We also won’t worry about photosynthesis or other chemical reactions involving energy for now.

    So, to get back to your question, rephrased as “what is the relationship between ocean and air temperatures?”, the answer is “it depends”, and it depends on the current balance of the various energy terms. In particular, it can vary depending on the relative size of the terms that carry energy away from the surface to the atmosphere, versus the term that carries energy into the ocean. Solar radiation is always a net input, IR radiation is usually a net loss to the atmosphere, thermal and evaporative fluxes are usually a net loss to the atmosphere when net radiation is high, and thermal energy into the ocean is also usually a net input to the ocean when net radiation is high. At night, when solar input is zero, net IR is a loss, and both air and ocean will be moving energy towards the surface to make up for the IR loss.

    All this can be expressed mathematically, and the relationships quantified. To know longer-term averages, you really need to (in the absence of sufficiently-detailed direct measurements) run climate models. As a broad sweeping generalization, the atmosphere gets its heat primarily from the surface, where most of the solar energy is absorbed, and atmospheric temperature decreases with height. (There can easily be several degrees of difference between air temperature at 2cm, and 2m. Think hot sidewalk on a summer day. Then think cool grass, which has the same air temperature above it at 1.5m, but a very different surface temperature where your feet make contact.) Ocean temperatures, where sunlight penetrates to some depth and water is mixed thoroughly, will tend to be a bit more uniform to moderate depths (metres to tends of metres).

    Does this help? Does it lead to follow-up questions?

  46. 96

    #92–Thanks for linking my Fourier piece, Pete. I was going to mention Fourier in response to Titus, but you beat me to it.

    Essentially, Fourier laid out the broad outlines of a terrestrial heat budget, back in the 1820s. There were some things, like the ‘temperature of space’ about which he was pretty incorrect–quantitatively if not qualitatively. But his paper is definitely seminal, usually being credited as the first link in the chain of scholarship that led to the modern theory of climate and the greenhouse effect. As far as I know, that is definitely the case as far as theoretical groundwork goes.

    But my personal nominee for first “greenhouse” paper goes to William Charles Wells’ “On Dew,” which (in addition to achieving a very good analysis of its subject) provides a remarkable series of observations of what we now call “downwelling long wave radiation.” See:

    http://doc-snow.hubpages.com/hub/Global-Warming-Science-In-The-Age-Of-Washington-And-Jefferson-William-Charles-Wells

  47. 97
    Pete Dunkelberg says:

    SecularAnimist, be a bit cautious about demanding precise definitions or insisting that such are a necessary condition for much of anything. Do you think Newton, when developing calculus, had good definitions of “continuous function” or “real number?” Fourier, when developing advance mathematical techniques to analyze heat transfer much later, still got by without these. Indeed, can you define these terms off the top of your head? No? But you can do math anyway. And as the ultimate coup, recall that mathematicians finally decided to base it all on undefined terms!

    It is true that the use of the same term for different things without explanation may lead to confusion. See for instance What is the thermohaline circulation? (and somewhere I think there is an article on five definitions of heat found in scientific usage.)

    Often is is good to allow a concept, and so also a definition, to develop gradually over a long period of usage. Continuous function and real number are cases in point. Perhaps the THC is too. What about “number?” If you know the sort of constructs that the reals “are”, it is not unreasonable to ask if they are really numbers or something else. If you say yes they are numbers, then what about imaginary numbers? If you say yes again, then what of surreal numbers? It seems that the number concept is still not finished.

    What then of consciousness? You may think it is a state, but persons closer to brain studies are inclined to say it is a process. Some say that it develops through interactions, especially with other persons within a culture, and that an isolated human would lack it.

    What is a definition anyway? (By analogy with your comment SA, I shouldn’t talk about definitions without defining them ;) AFAIK the definition concept began to develop in the 6 to 5 hundreds BC. Somehow, people communicated long before. Regardless, a definition of a noun is in general a hybrid of two descriptions. First, it is a description of word usage. “When term T is used, it means this, or sometimes that, or ….” Second it is a description of a thing. “Granite is” – followed by describing certain minerals or even better pointing to same. Asking for an exact description of the second kind as a precondition for progress toward gaining that knowledge is not likely to help.

  48. 98
    Titus says:

    Pete Dunkelberg and SecularAnimist.

    Again my apology for taking this off topic. I appreciate your thoughtful comments. My interest is more basic than defining consciousness. Since my school days I have always had a niggling doubt about how a chemical reaction created a cell that could immediately self sustain and reproduce itself. Let alone evolve RNA for DNA and all that follows. Nagel’s book offers some thoughts on openings of thought processes. Only if you are brave and prepared to open yourself up.

    Back on topic: Thanks Eric for the confirmation of the low geothermal numbers. Interested if there is any development of thinking around the earth core energy taken up by driving the mechanical movements of the surface.

    Thanks

  49. 99
    Chuck Hughes says:

    So if we hit 450 ppm of CO2 in a few decades, what then?

    http://www.guardian.co.uk/environment/2013/apr/29/global-carbon-dioxide-levels

    “I wish it weren’t true but it looks like the world is going to blow through the 400ppm level without losing a beat. At this pace we’ll hit 450ppm within a few decades,” said Ralph Keeling, a geologist with the Scripps Institution of Oceanography which operates the Hawaiian observatory.

    The last time CO2 levels were so high was probably in the Pliocene epoch, between 3.2m and 5m years ago, when Earth’s climate was much warmer than today.

  50. 100
    Hank Roberts says:

    > created a cell that could immediately …

    That’s your problem: you describe events unlike what those studying the subject think: not “created” and not “a cell” and not “immediately able”

    As Chris Smither says, evolution is not something you believe in.
    It’s just something you know about. Or don’t.

    Starting from the research being published gets you started toward a clearer idea of the state of the science as it develops.

    Starting from what you imagined, you’re arguing with people who aren’t here.


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