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Why greenhouse gases heat the ocean

Filed under: — group @ 5 September 2006

Guest commentary by Peter Minnett (RSMAS)

Observations of ocean temperatures have revealed that the ocean heat content has been increasing significantly over recent decades (Willis et al, 2004; Levitus et al, 2005; Lyman et al, 2006). This is something that has been predicted by climate models (and confirmed notably by Hansen et al, 2005), and has therefore been described as a ‘smoking gun’ for human-caused greenhouse gases.

However, some have insisted that there is a paradox here – how can a forcing driven by longwave absorption and emission impact the ocean below since the infrared radiation does not penetrate more than a few micrometers into the ocean? Resolution of this conundrum is to be found in the recognition that the skin layer temperature gradient not only exists as a result of the ocean-atmosphere temperature difference, but also helps to control the ocean-atmosphere heat flux. (The ‘skin layer‘ is the very thin – up to 1 mm – layer at the top of ocean that is in direct contact with the atmosphere). Reducing the size of the temperature gradient through the skin layer reduces the flux. Thus, if the absorption of the infrared emission from atmospheric greenhouse gases reduces the gradient through the skin layer, the flow of heat from the ocean beneath will be reduced, leaving more of the heat introduced into the bulk of the upper oceanic layer by the absorption of sunlight to remain there to increase water temperature. Experimental evidence for this mechanism can be seen in at-sea measurements of the ocean skin and bulk temperatures.

During a recent cruise of the New Zealand research vessel Tangaroa, skin sea-surface temperatures were measured to high accuracy by the Marine-Atmospheric Emitted Radiance Interferometer (M-AERI), and contemporaneous measurements of the bulk temperature were measured at a depth of ~5cm close to the M-AERI foot print by a precision thermistor mounted in a surface-following float. The M-AERI is a Fourier Transform Infrared spectroradiometer that has very accurate, NIST-traceable, calibration. The skin temperature can be measured with absolute uncertainties of much less than 0.1ºK The thermometer in the surface following float is accurate to better than 0.01ºK. Both are calibrated using the same equipment at the University of Miami.

Clearly it is not possible to alter the concentration of greenhouse gases in a controlled experiment at sea to study the response of the skin-layer. Instead we use the natural variations in clouds to modulate the incident infrared radiation at the sea surface. When clouds are present, they emit more infrared energy towards the surface than does the clear sky. The incident infrared radiation was measures by a pyrgeometer mounted on the ship, and the emission from the sea surface was calculated from the Stefan-Boltzmann equation using the skin temperature measurements of the M-AERI. The difference between the two is the net infrared forcing of the skin layer. If we can establish a relationship between the temperature difference across the skin layer and the net infrared forcing, then we will have demonstrated the mechanisms for greenhouse gas heating the upper ocean. That is seen in the flow chart on the right.

The figure below shows just the signal we are seeking. There is a clear dependence of the skin temperature difference on the net infrared forcing. The net forcing is negative as the effective temperature of the clear and cloudy sky is less than the ocean skin temperature, and it approaches values closer to zero when the sky is cloudy. This corresponds to increased greenhouse gas emission reaching the sea surface.


Figure 2: The change in the skin temperature to bulk temperature difference as a function of the net longwave radiation.

There is an associated reduction in the difference between the 5 cm and the skin temperatures. The slope of the relationship is 0.002ºK (W/m2)-1. Of course the range of net infrared forcing caused by changing cloud conditions (~100W/m2) is much greater than that caused by increasing levels of greenhouse gases (e.g. doubling pre-industrial CO2 levels will increase the net forcing by ~4W/m2), but the objective of this exercise was to demonstrate a relationship.

To conclude, it is perfectly physically consistent to expect that increasing greenhouse gas driven warming will heat the oceans – as indeed is being observed.

Acknowledgements:
The need for such an analysis grew out of a series of discussions with S. Fred Singer. The M-AERI was developed with funding from the Earth Observing System program of NASA. Participation in the SAGE cruise was supported by a grant from the NSF (OCE 0327188). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author and do not necessarily reflect the views of the National Science Foundation.


94 Responses to “Why greenhouse gases heat the ocean”

  1. 51
    Yartrebo says:

    Those percent increases for coal and oil use are way out of line. Oil is growing more like 1% or 2% a year and is very well documented (ASPO has assembled some awfully detailed historical information on oil if you want to check – http://www.peakoil.ie/), and coal maybe 2% (good figures on this are hard to come by, since little coal is traded internationally). 7.5% growth would be a nightmare scenario, as emissions would double every ten years. It happened with oil between WWII and the first Oil Shock (1970 or so), but it’s unlikely to happen for oil, coal, or natural gas ever again because of geological constraints.

  2. 52
    John L. McCormick says:

    Yartrebo, I used British Petroleum’s energy statistics at:

    http://tinyurl.com/nyj5b

    Using the BP data and my hand-held calculator, the increase for coal, 2003-2004 is 6.8%, oil, 4.3% and natural gas 2.6%. Sorry to break the bad news to you. Check the data yourself. And, that was not the point of my retort to Mr. Turner. Please read his comments, then mine. I believe you will see MPOV.

  3. 53
    steve says:

    Thank you Bryan. I do hope that someone will clear this up for me. However, it looks like perhaps this thread is winding down and I came too late. It only occured to me today, after looking at threads in various places for about the past week that I have really not heard much about the stored potential energy from the sun. ( I haven’t had the guts to post before that first one, but maybe that will be easier now.) My question really hinges on what that balance is. For instance, if we are truly burning fossil fuels, then presumably (from my estimation, correct me if I am mistaken) that fuel we are currently using was at one time derived from solar energy and stored as coal and oil. If this is true, then it appears that during the time which that energy from the sun was stored on the planet, the radiative fluxes to space may have been less than the input from the sun. Another example may be that of hydroelectric power. There is quite a bit of energy stored behind a dam. I don’t know how much or if it is enough to be significant, but I believe based on my limited science background that much of that water was lifted from the oceans, using solar power, and deposited at high altitudes at various places on earth. This is work. The fact that we can derive power from this work tells me that potential energy has been stored on the planet, apparently solar energy. I do not pretend to know the magnitude of these various stored energies. Certainly geothermal is not solar in origin, and could not be included. I do not have the faintest idea what the energy balance is with respect to the sun. Is the earth’s potential energy increasing or decreasing? Maybe no one is sure at this time, or maybe someone does have an answer. I’m glad that you didn’t just toss the question aside, because I think it is a neat one. If the planet warms, causing more water to be transported to higher elevations (work, possibly resulting in stored potential energy, which may have originated in the kinetic energy deposited by the sun) does the additional work done take enough from the solar kinetic energy to allow for a balancing impetus to the expected temperature increase? I did not see this addressed, at least not explicitly on the “greenhouse effect” page of Wikipedia, my primary information source. I’m not even certain how to go about calculating the sums of possible potential energy stored per year of solar origin, but with all the folks working in the field, I’m sure someone has done the work. I suppose it would be more industrious of me to try and sort out the literature, but I was hoping to take the easy way out and have someone hand me the answer. Now I really want to know, and I don’t have enough background to understand this point. I have been thinking of the earth as a heat engine that absorbs from a hot source, deposits to a cold source, and does work, some of which is stored as potential energy, but I don’t know how much or if the rate at which we are currently releasing that stored potential by burning fossil fuels has radically changed that balance as well. It is possible that due to fuel burning, the potential currently being released, which was stored for a long time, is making the situation worse and, coupled with reduced radiative losses, is adding to the atmospheric heating. Also, perhaps increased CO2 and heat increase the rate of plant growth, and somewhat balance that effect. All I want to see is some kind of treatment of the earth’s potential energy of solar origin, or some reason (hopefully that I can understand) of why it is cancelled in one fashion or another and can be dismissed. Again, I only ask because my limited review, for the last week, of some of the internet discussions, heavily implies that one of the bases for the calculations of how much global warming to expect is the assumption of radiative equivalence between the energy coming from the sun and that leaving through the atmosphere, to allow the planet to maintain a more or less stable temperature, which is related to kinetic but not potential energy. I am curious if considerations such as the ones I have mentioned will in any way affect those calculations, or if they are already included.

  4. 54
    steve says:

    Sorry Graham,

    I didn’t see your reply until after I wrote the next one. I appreciate your response.

    Steve

  5. 55
    John L. McCormick says:

    RE # 50

    Bryan, my post at #48 was intended to respond to Mr. Turner’s post at

    the thread titled: How do we know that recent CO2 increases are due to human activities?

    He posted the following:

    [This is an attempt to make wishy/washy data look much more reliable than it really is.

    I do agree that global warming is taking place but it is my position that the level of CO2 in the atmosphere is growing BECAUSE of global warming. I have yet to see any reasonable argument that can challenge my proposition].

    My data, from the BP Energy Stats, refute his proposition. I know most RC contributors

    [comprehend and fully embrace Wein's Displacement Law and Stefan Boltzmann, but are not yet convinced they completely understand the whole process of how the dynamic earth/ocean/atmosphere climate system works.]

    I thought it was of some value to suggest to Mr. Turner that global warming is partly the cause of the increasing level of CO2 in the atmosphere, (positive feedback from warm oceans and land) but fossil fuel combustion is the primary reason in light of the fact that CO2 concentrations prior to the IR were essentially level (roughly 280 ppmv)going as far back as you choose.

  6. 56
    L. David Cooke says:

    RE: #53

    Hey steve;

    If I understand correctly, I think your question maybe more of, “Given the current energy input by Sol what is the energy balance?”. I believe what many have shared here is that there are large variations in these values. For your purposes I think this could be simplified with a short answer based with an approximation of the current observations. (Note: Not that I am an expert; however, I have recently enjoyed an educational opportunity that attempted to addressed this question.)

    In essence at the Top of the Atmosphere (TOA) the total incoming Solar energy is approximately 1368-1374 watts per meter^2, (it depends on which satellite and the time frame you are considering). At the surface the incoming value can range from between 15 and 850 watts per meter^2 depending on latitude, weather and the seasons. Generally, it appears that the incoming energy averages somewhere between 250 to 300 watts per meter^2 across the surface facing the sun. (A good source for radiative measurements can be found at http://www.arm.gov. A reasonable text might be “Energy, its Use and the Environment” by Hinrichs and Kleinbach.)

    Of the roughly 300 watts per meter^2 reaching the surface, it appears that over the long haul about 60 watts per meter^2 might become sequestered for some time period with a average current total radiative balance around positive 2 to 8 watts or an average of around 1.5 to 2 watts per meter^2. (Note: See Hansen et al (2005) (Reference NASA’s Goddard site at ( http://data.giss.nasa.gov/gistemp/2005/ or a slight discussion of planetary energy imbalance with references at http://www.earthinstitute.columbia.edu/news/2005/story11-04-05.html ), which suggests of the approxiamte incoming 300 watts around 0.85 watts are noted as an increase related to the current global warming phenomena.) Of the @ 60 watts of sequestered energy approximatly 60 watts per meter^2 per day might be sequestered for the long haul and be entombed in either methane hydrates or ionic compounds sequestered in the ocean floor. Based on the suggestions here in this post it looks like more then 90% of Sol’s energy locked up in hydrates or oxides are likely released in natural geologic activities on the order of millions of years. (This current apparent positive balance can easily be overcome by an ice age glaceriation effect and the release of the balance may be the only means of the ice age receeding.) This remains a point for discussion in many circles the least of all might be here. Does this help?

    Dave Cooke

  7. 57
    Ray Lopez says:

    I’ve read this thread and would like to point out a possible reason the oceans, which act the same way a capacitor acts in a RLC circuit, namely to store energy, might be the cause of global warming: ENSO events will alter weather patterns, release heat and CO2 into the air. Thus ENSO events, which statistically have increased in the last 25 years, are the cause, not the effect, of increased global warming. The analogy is discharge of a capacitor’s energy back into the RLC circuit when the capacitor is overloaded, or simply due to cyclical flucuation.

  8. 58
    Leonard Evens says:

    Cause of growth of CO_2 concentration.

    It is well established that CO_2 concentration is growing because of human activities. This is not today a matter of serious debate. While nothing in science is ever established beyond all possible doubt, some things are really not worth pursuing further without overwhelming evidence supporting the contrary opinon. I suggest that anyone who argues otherwise in this forum should be categorized as eccentric, at best.

  9. 59
    John L. McCormick says:

    Bryan, RE # 50

    You asked me to accept [beyond the fundamental laws however, there is a bunch more we are not as sure about.] Yes, lots we are not sure about.

    And, you suggested [Hopefully, we can all agree that we need to continue this wonderful research endeavor to better understand this fascinating and important portion of earth science.] Yes, the international science community, with public funding and support, must continue [this wonderful research endeavor to better understand this fascinating and important portion of earth science.] Earth science is fascinating for this layperson and I thank the RC contributors and the legion of gifted scientists providing us with insights into the workings of our marvelous planet.

    But, the more I learn the more anxious I become.

    I am interested in the most intricate and compound workings of the earth/ocean/atmosphere climate system but smelling the smoke is enough for me to call the fire department.

    I know the Arctic long-term sea ice is diminishing. High altitude ice in the Andes, Alps and Himalayan mountains is melting (locals say the melting is rapid). Western North American mountain snow pack is diminishing and melting earlier as stream flows indicate less water availability for the densely populated cities of the Southwest.

    And, I have a reasonable suspicion that US, China and Indian coal deposits are destined for synthetic oil and electric power stations. That **certain** increase of CO2 emissions will not be sequestered despite the irrational (self-serving) optimism of coal interests and despairing hopes of some environmentalists. That idea is a non-sequester.

    That leaves me and us with more research and less time to prepare for what is about to hit our children hard and fast.

    When will you be satisfied you have enough knowledge to separate your desire for more understanding from your demand for action (both mitigation and adaptation)? What is your convincing tipping point?

  10. 60
    steve says:

    Dave, RE #56

    Thank you. That does help. I appreciate the direction to other websites of interest that will shed more light on the issue.

    Thanks,
    Steve

  11. 61
    Steffen Christensen says:

    Re: steve’s #53. Estimates of the total power generated by the Earth (mostly from radiological heating, but also from settling, phase conversion, and primordial heat) run around 30 TW (terawatts) ( http://www.es.ucsc.edu/~afisher/CVpubs/pubs/VonHerzen2005_TectComment.pdf ). The Sun sends about 174 000 TW of power towards the Earth’s disk, a lot of which doesn’t make it to surface. The average power delivery, over all the seasons and the whole Earth (not just the part facing the Sun), is around 31 000 TW, as estimated from Earth’s mean temperature of 15 degrees Celsius and a Bond albedo of 0.29. So the Earth’s self heating is around 0.1% of the Solar heating.

  12. 62
    savegaia.de says:

    As life is common in space, enhanced civilizations will face the same planet global warming problems which ouccur by civs emission.

    So why is the planet climate so fast to un-balance?
    Is it to stop specific kind of lifeforms?
    Is it an big IQ test?

    It’s all about critical mass, so about the convincing tipping point of each single beeing will make desisions.
    The problematic is basicly lifeforms start to requognize global events rather late.
    So is this part of a test our species faces here, do we need a 100,00 years break of favourable life conditions – and even we not survive such a break?

    Mankind has the potential to counter earth fever, we are rightnow at the tipping point.

  13. 63
    Yartrebo says:

    Re 52: Don’t take a banner year (for the fossil fuel industry) and extrapolate out into the future. Also, don’t rely on only one source for your information, especially a biased industry source. Claiming that oil production is growing at a 5% rate and coal at 7.5% is a very far out claim. It might be so, but it’s such a high number that it needs to be backed up with some serious data and reasons to explain why in a world economy growing at a few percent a year, energy usage is growing by around 5% a year (coal and natural gas are about 20-25% of the world energy supply each, and oil is about 40%, which works out to a 5% weighted average using your numbers).

    Increases in fossil fuel usage almost always lag behind GDP growth (because of systematic underreporting of inflation?), and worldwide GDP growth is usually a few percent a year, including every year from 2000 to 2006. China might be racing ahead and chalking up 5-10% emissions increases and 10% GDP growth, but Europe has close to 0% emissions growth. For a worldwide average, 2% growth in energy usage is considered fairly rapid.

    If energy usage was indeed growing at 7.5% long term (with that kind of growth rate, coal would approach 100% of the energy supply in a few decades), then we would have to worry about a lot more than global warming – things such as oxygen depletion (only 20% or so of oxygen available) and carbon dioxide poisoning (over 5% is quite fatal) would become major issues as 2100 came along as coal usage would increase about 1,000-fold (doubling once every 10 years). CO2 levels would be around 1.5% and growing by about 0.2% a year. Obviously 7.5% is a ludicrous rate for long term fossil fuel usage.

    The rest of your argument is quite sound, but the energy numbers and extrapolation you posted are just really out of whack. Please check your numbers with various sources, including some non-industry and non-government sources (those two tend to be perennial optimists). I’ve done so, and you can find all sorts of contradicting information (after all, it’s economics and politics, two fields full of manipulation and lying). Often even basic definitions (ie., what is oil) are different from source to source, leading to very different numbers.

  14. 64
    L. David Cooke says:

    RE: #57

    Hey Ray;

    I have seen a clear indication in the Sept 2005 Duke study alluding to the capacitive coupling of heat content increase to the worlds warming. However, I have also observed that Sol’s output indicates an inductive character. If the cycles of source and the heating were in phase then as Sol was at maximum then the earth’s content would be at minimum. When Sol was at minimum then the earth’s content could be at maximum. To put the current GW character into your engineering perspective then if the phase has shifted such that the peaks matched could be a partial explanation for GW.

    How would this “phase” be changed would be the question to address. Has the sun’s energy cycle shifted or has the Earth’s heat cycle shifted? Based on all the data here it appears that the Earth’s heat content has not “discharged” sufficiently through the atmosphere into space. (As in a LCR circuit with a wave length of 11 or 22 or 41 odd years.)

    Given this it would appear that the additional Solar energy is going into increasing the ambient earth heat content. However, if the discharge path is simply at a higher resistance and not an open circuit then simply put the heat content will increase until either the capacitor or the resistor fails. (However, unlike normal engineering rather then the resistor failing open, in this case it should fail short circuited.)

    So what happens if the capacitor fails, it would be likely the heat content out is going to match the heat content in. Does this characteristic match any historical data? Unless the worlds oceans are a good conductor I would suggest this is unlikely. It would be more likely for evidence to the opposite, that the capacitor fails open rather then the normally expected short circuit.

    If the character of a failed capacitor is not observable then it must be the resistor that fails. Meaning that at some point the energy content rises to the point the resistor shorts out and the heat content is dropped suddenly. This characeristic would be very similar to what was observed in the 2005 hurricane season in the N. Atlantic, a sudden release of heat to the upper atmosphere where it can be transported to the Poles for emission into space. (Now if we simply had the means to observe a IR plume at the poles this effect should have been clearly observable.)

    Apparently, the ENSO and the PDO are likely natural phenomena that seems to be a sign that this “discharge” event has occurred. As of yet I have seen no other hypothesis that would explain these atmospheric characteristics. (If you have a better explanation of how these events occur I would be very interested in reading them.)

    Granted even my explanation is not a great model either; however, defining the devices and the circuit accurately can be important, if you want to accuratly explain long term weather or small term climate outlooks from a model. My concern when reading your post appeared to be the character you had alluded too did not match my understanding. Have you a better definition of how you see the components and the circuit schematic?

    Dave Cooke

  15. 65
    John L. McCormick says:

    RE #63

    Yartrebo, lets give it a rest, huh. If you cannot trust BP to use figures that did not come from a .org web page, then we have nothing to discuss.

  16. 66
    KC Truby says:

    So, we have conflicting reports in the SAME YEAR.

    Ocean Cooling Confounds Climate Models
    Climate Science, August 14, 2006
    A new study of ocean temperatures indicates significant cooling over the years 2003-2005. This unexpected result has implications for climate models. As Roger Pielke SR of Colorado State University says, “The explanation of this temporal change in the radiative imbalance of the Earthâ??s climate system is a challenge to the climate science community. It does indicate that we know less about natural- and human-climate forcings and feedbacks than concluded in the IPCC Reports.” Read more analysis from Professor Pielke here.

    The Competitive Enterprise

  17. 67
    Phil B. says:

    Peter Minnett, I enjoyed your writeup. I have a question. Using the basic conduction equation from my physics book and length of L=.05 m, thermal conductivity of k = .585 W/m-K, and a delta T of -.25 K, I get ~ -3 W/m^2. If I look on your chart for night time conditions you have about -88 W/m^2. A substantial difference. What am I missing here? Thanks Phil

  18. 68
    Yartrebo says:

    John, why do you have such faith in the BP numbers? They have the scientific rigor of a press release. That rate of growth (7.5% for coal, 5% for oil) gives a 2100 projection that’s more than 100-fold over the IPCC business-as-usual projection of CO2 emissions.

    When much simpler possible explanations exist such as tar sand production being reclassified as oil production (without backdating – a common error in the energy industry) and the admission of China that coal production was severely understated (again, without backdating), why go with the explanation that stretches believability (that we’ve entered a brave new world where energy usage races ahead and breaks all historical ties to GDP growth). I’m not saying those are the reasons, but they are two very large events that have happened in the last two years and could completely throw off (to the upside) any statistics that aren’t properly backdated.

    I cannot prove or disprove any of these allegations because BP keeps secret how it comes up with its numbers, but the onus should be on BP to prove that their numbers are accurate, and they have failed to do that.

    PS: Backdating means that if you change the definition of something (like now including bitumen as oil production), you revise the old data so that bitumen is also included in the old data. It’s so obvious that it’s generally taken for granted in science, but in the energy industry it’s often not done (probably for political purposes, since the revisions are almost always up and not down).

  19. 69
    Robin Johnson says:

    Uh… Yartrebo and John.

    John-
    I don’t think that you should extrapolate from two years data. Plus, fossil fuel production is not the same as fossil fuel consumption. Coal and oil are often stockpiled – oil and coal stocks often exceed many months of supply – and with Middle East tensions and expectations of increased prices – stockpiling would not be surprising. Additionally, there are plenty of good historical data sources available. Try some searches over at The US Department of Energy. The International Energy Review 2004 provides spreadsheet data (that’s quite interesting for stat heads). Additionally, according to The EIA, 2005 over 2004 was only a 1% increase (the 2004 4% increase over 2003 was slightly anomalous it would appear). (1997 over 1996 showed a similar anomaly of 3%).

    Yartrebo-

    On the other hand, the acceleration of energy consumption by India, China, Middle East and South America from increasing population and increasing consumer Western style consumption WILL drive energy usage up – India and China instead of leapfrogging into modern technologies are adopting inefficient but quick and cheap energy technologies. Oops. So I fully expect energy usage to balloon beyond the usual 1-2% increase with the recent population bulges in Southwest Asia, Africa and Latin America along with increased Westernization. As the oil runs low – coal gasification will become economical [double the CO2 increase per barrel] so things will definitely get worse from a CO2 perspective. So, to say that that fossil fuel consumption growth is going to stay at 1-2% per annum may not be true. Even 2% growth is ruinous – twenty years of 2% growth translates into a 50% increase. Cue the doom music…

  20. 70
    Robin Johnson says:

    And I should have added, according to the IEA – world coal usage grew 8% in 2003 and 7% in 2004. World natural gas usage grew 4% per year in 2002, 2003 and 2004.

  21. 71
    John L. McCormick says:

    RE # 68, 69, 70

    Folks, are we dancing on pinheads again?

    The fact I included one-year growth percentages of oil, coal gas, production (consumption????–what does that really matter- the fuel will be consumed) has absolutely nothing to do with my original response to Mr. Turner’s post at the thread titled:

    How do we know that recent CO2 increases are due to human activities?:
    22 DEC 2004

    PLEASE read his post on the other thread then my post at #48 here and try to see the salient point I was offering Mr. Turner to consider.

    There, I said increased fossil fuel production (and of course fossil fuels are produced for consumption even if they are stockpiled for a rainy day) emitted more CO2 than sinks can accommodate so the atmospheric CO2 concentration increased. Because of global warming? To the degree that warmer oceans and land presented positive feedbacks of CO2; YES.

    I say, be done with the discussion about Yartrebos interpreting my 2003-2005 growth percentage as a projection of future fossil fuel production. I DID NOT MAKE PROJECTIONS. Enough! PLEASE.

  22. 72
    Graham Dungworth says:

    There is an alternative way to check the growth of emissions. Firstly, look at a global polltion map from envisat that dates back to 2002. I’ve asked them to update it a year ago, to no vail yet
    GLOBAL POLLUTION>
    Secondly,the most up to date figure plots of the famous Keeling curve which shows the build up of CO2 in the atmosphere are available from NOAA. They were not available for a year prior to this January passed, a consequence of grant funding cancellation by the US administration. Many, complained bitterly, inc myself so they were reintroduced.
    KEELING CURVE>
    The CO2 graph opens for Mauna Loa in the central Pacific. Click for other locations. The saw tooth is a consequence of photosynthesis in the Northern Hemisphere starts in Spring and plants absorb CO2 so the amount of CO2 drops. At the end of the growing season plant life decays releasing excess CO2 into the atmosphere and the build up of CO2 occurs through to the following spring. Keeling noted that most productivity which is land based occurs in the Northern Hemisphere and dominates that for the southern hemisphere.
    If you toggle for isotope 13CO2 data another fascinating factor is explained as such.
    Firstly, From the pollution map it is evident that most fossil fuel combustion occurs in the Northern Hemisphere. If you toggle around for many other global stations it becomes evident that it takes between 6 months to 1 year for CO2 released to diffuse around the atmosphere.
    Secondly, a bit of detailed chemistry is relevant.
    Carbon is recycled geochemically by CO2 emissions from volcanoes, oceanic ridges, wethering of limestiones and calcareous shales etc. Biosynthesis by life, namely photosynthesis, preferentially selects the common isotope 12C(99% abundant) because the heavier stable isotope 13C(1% abundant)is kinetically slower, it doesn’t diffuse into leaf tissue or calls as quickly. The carbon in fossil fuels such as coal/oil is isotopically light, ie it is depleted in the heavier 13C isotope. By definition, limestone,CaCO3,is taken to have zero depletion ie. 0 on a parts per thousand(mil) scale. Coal/oil etc when analysed give values of ca. -30 per mil ie. the negative sign means they are depleted in the heavier isotope by 30 patrs per thousand relative to the defind 0 depletion or enrichment for limestone. Some biogenic gases eg methane are often even more depleted down to -50 per mil.
    When you look at the C isotope fractionation for CO2 in the atmosphere it is vastly different. It used to be ca. -7 per mil in agreement with volcanic emissions, igneous carbon and even diamonds. Currently, the value is below -8 per mil. The most depleted value is in Korea, I presume because of all the industrial emissions from China. For Mona Loa you can see a variable trend where recently CO2 in the atmosphere is getting isotopically lighter by 0.06 per mil annually.

    The CO2 isotope values can be used to do a mass balance on atmospheric fossil fuel emissions. The mass of the atmosphere is 5.12*10exp21g. If CO2 is 385 ppm(by volume) we can calculate the mass of CO2 knowing its atomic mass is 44 and that of the other components(N2 and O2 etc)average 30; so we have to multiply the volume mesure by 44/30 to get CO2 mass measure.
    It is claimed by the IPCC that ca. 5.7 gigatonne CO2(note carbon is atomic mass 12, to get gigatonne C we would multiply by 12/44 since CO2 is C plus 2*O(oxygen=atomic mass 16))is combusted annually.
    THAT fossil fuel combustion has an isotope C of -30per mil. It dilutes the heavier ca.-8 characteristivc of the atmosphere as a whole.
    From one year to the next the mass balance is
    Total Mass carbon(yr1)*fractionation factor1= Total Mass carbon(yr2)*fractionation factor2 + (X*-30)where
    X=gigatonne fossil CO2 generated from yr1 to yr2.

    Doing all of that, from Mona Loa data that I think is the best database, I got 5.78 Gigatonne CO2 from current fossil fuel released recently per annum.
    Hence, There is no justification for claiming that fossil fuel combustion rates are growing by that huge 7-8%.
    On errors- -30 I think is the value I think was used to corroborate former IPCC book values.There are accumulations of Russian biogenic gas that fractionate down to -70. This would reduce the apparent isotope determination of combusted fossil fuel. Nevertheless,
    if we see a marked increase in that downslope isotope gradient we will be aware of it within a time frame of months.
    Both the envisat polltion map, if updated annually? and the carbon isotope database will provide a valuable alternative method for checking on national and global emissions.

  23. 73
    Graham Dungworth says:

    Re# Apologies.
    For GLOBAL POLLUTION
    http://www.esa.int/esaEO/SEM340NKPZD_index_0.html

    For KEELING CURVE
    http://www.cmdl.noaa.gov/ccgg/iadv/index.php

  24. 74
    John L. McCormick says:

    Graham, thank you. A very interesting post.

    But, I believe the following is in need of adjustment.

    You said:

    [It is claimed by the IPCC that ca. 5.7 gigatonne CO2(note carbon is atomic mass 12, to get gigatonne C we would multiply by 12/44 since CO2 is C plus 2*O(oxygen=atomic mass 16))is combusted annually.]

    [5.7 gigatonne CO2] should read 5.7 gigatonne Carbon, which multiplied by 44/12 or 3.667 would yield 20.9 gigatonnes of CO2. I see this reversal often; C becomes CO2 and CO2 becomes C even among the pros.

    Do you agree?

  25. 75
    Graham Dungworth says:

    Re#74
    Greatly appreciate your comment John. You are absolutely correct. Also, the following paragraph reading “Doing all of that ..” should be corrected to read 5.78 Gigatonne C from current…
    For the mass balance we have 1971.2 Gigatonne CO2 in dry atmosphere; equivalent to 537.6 Gigatonne C in atmosphere; for which the observed isotope fractionation factor is -8.40 in yr1 and then -8.46 for yr2. The fossil fuel isotope fraction is assumed to be -30.

  26. 76
    Ray Lopez says:

    Re #64 L. David Cooke – I enjoyed your post. It brought back memories of solving second-order differential equations with constant coefficients. Of course the real world is not as simple but oftentimes a simple model will approximate reality to an astonishing extent. I particuarly liked this passage of yours: >>Apparently, the ENSO and the PDO are likely natural phenomena that seems to be a sign that this “discharge” event has occurred. As of yet I have seen no other hypothesis that would explain these atmospheric characteristics.< <

    This is the issue: if ENSO and PDO are signs of the "discharge", then does it lead or lag CO2 production? Recall it depends in an RLC circuit on the damping factor and/or time constant parameters (see - http://en.wikipedia.org/wiki/RLC_circuit). Even if C02 is a forcing function (see the section “Convolution Integral” in the Wiki article) the response of the earth would depend on the time constant/ damping of the circuit. I don’t know enough about modeling the earth to give an answer, but I doubt anybody has actually done this sort of calculation–most likely climate scientists simply do linear regression statistical analysis rather than trying to actually come up with a closed-form solution equation. A statistical analysis will never give a cause or effect answer, just correlation. But it is entirely possible that the ENSO/PDO events are “leading” GW rather than “lagging” (i.e., they are a “cause” of GW not an “effect”). One possible physical explanation: the heat trapped in the earth from 1000s of years of activity (human or otherwise) is slowly coming out of the system, even though there is not that much extra CO2 being produced to explain the jump in temperatures since 1981. Certainly perfecting such a model would explain the heretofore unexplained jump in ENSO/PDO that occured in the late 20th century, which apparently is the basis for the concern over global warming.

  27. 77
    Wacki says:

    “when clouds are present, they emit more infrared energy towards the surface than does the clear sky.”

    What? I thought clouds were a negative feedback. I thought the light color bounced radiation back into space. Is this not true? From your “lessons from venus”:

    Because of the cloud cover, the surface temperature of Venus would be a chilly -42C if were not for the greenhouse effect of its atmosphere.

    http://www.realclimate.org/index.php/archives/2006/04/lessons-from-venus/

    [Response: Clouds have multiple effects. They change the albedo (a cooling effect), but they also absorb and emit LW radiation (a warming (greenhouse) effect. The net effect of any one cloud is a complicated function of it's height, 'thickness', the temperature profile, ground conditions below etc. -gavin]

  28. 78
    L. David Cooke says:

    Hey Ray;

    It is too bad I would not be able to hold a serious conversation regarding second-order differential equations. I think we could have a fun discussion off line. However, all I am is a simple self taught Technical Specialist/Network & Systems Engineer who is trying to return to college after 30 years for a BA, possibly in Earth Science EDU.

    I did pursue your reference to the Convolution Intregral, it appears in the text to be related to impulse inputs, the problem is the inputs we are discussing are clearly Sinusoidal in nature. I even went so far as to look up the reference to the dirac delta tranform and the Cauchy distribution. The Cauchy distribuiton may be related though there does not appear to be a clear relationship, we acutally have a mean that has values on both sides of the reference; however, the mean is ever increasing and the values rarely ever return to the former levels in the early sample time period. (A true normal distribution would have outliers on both sides of the mean regardless of sample time.)

    This was the reason that Dr. Elsner’s study was so interesting. He actually applied the Granger Test very well. The problem for me was the “Tounge in Cheek”, treatment of a low density gas heating a high density liquid. As to the Layman et al, I see some interesting data; however, I don’t know that this is not a deviation rather then a trend or a sign of the new plateau.

    Following the Cauchy Distribution took me to the Hodgson’s Paradox. It almost seems appropriate to the discussion and maybe appropriate in regard to the current climate change discussions. I did find your thoughts on the ENSO/PDO to be an interesting viewpoint. I always thought the East-West ITCZ NH flow to be the normal movement and the West-East ITCZ NH flow to be the reaction that feed the heat content release into the Polar Easterlies. However, in your response I saw you indicting the case of “leading GW rather then lagging” and that brings up the question which is normal and which is the reaction…? During a cooling trend would these cycles reverse?

    Dave Cooke

  29. 79
    Mark UK says:

    With regard to the BP numbers… Unfortunately most of that data is at best “guestimates”. The private oil companies are accountable to some extent on their numbers, but the national oil companies in most cases either do not have accurate data on their production, consumption or reserves or choose not to release this information. There is no checking mechanism in place for national oil companies and they sit on by far the largest oil reserves. So, those BP numbers, don’t put to much confidence in them. They are simply collected from all sorts of sources without any rigorous study as to their validity…

  30. 80

    Okay, I have a denialist who also denies CFCs affect ozone. Her latest line is that the ozone hole should be over cities where CFCs are used, not the poles. I was almost ready to answer that and realized I didn’t know the answer. Why are the ozone holes at the poles?

    -Confused in Pittsburgh

  31. 81
    Jeffrey Davis says:

    Re: 80

    http://www.soest.hawaii.edu/GG/ASK/ozonehole.html

    (Google Query: Why are ozone holes at the poles?)

  32. 82
    Leonard Evens says:

    Barton, re 80:

    The link Jeffrey gave explains the polar vortex and why it leads to an ozone hole in the south over the antarctic and to a lesser extent in the north over the arctic. The other important point is that CFCs are well mixed in the atmosphere and by the time they get to the stratosphere they would certainly not be concentrated in any specific region. See

    http://www.faqs.org/faqs/ozone-depletion

    for an extensive discussion of all aspects of ozone depletion. It is a bit out of date, and I’m sure there have been some refinements, but it answers all the basic question and addresses all the points typically raised by denialists. It specifially addresses various misunderstandings based on not recognizing that the ozone depleting gases are well mixed and it explains the specific atmospheric characteristics at the poles which lead to the vortex and the ozone holes.

  33. 83
    Joseph O'Sullivan says:

    RealClimate had a post that had a short and easy to understand answer for why ozone depletion occcurs at the poles

    http://www.realclimate.org/index.php/archives/2005/04/ozone-depletion-and-global-warming/

    Here’s a more detailed paper about ozone depletion
    http://ozone.unep.org/index.asp
    In particular this:
    http://ozone.unep.org/Public_Information/4D_PublicInfo_FAQ.asp

  34. 84

    Many, myself included, found this post confusing.

    Observations of ocean temperatures have revealed that the ocean heat content has been increasing significantly over recent decades (Willis et al, 2004; Levitus et al, 2005; Lyman et al, 2006). This is something that has been predicted by climate models (and confirmed notably by Hansen et al, 2005), and has therefore been described as a ‘smoking gun’ for human-caused greenhouse gases.
    However, some have insisted that there is a paradox here – how can a forcing driven by longwave absorption and emission impact the ocean below since the infrared radiation does not penetrate more than a few micrometers into the ocean? Resolution of this conundrum is to be found in the recognition that the skin layer temperature gradient not only exists as a result of the ocean-atmosphere temperature difference, but also helps to control the ocean-atmosphere heat flux. (The ‘skin layer’ is the very thin – up to 1 mm – layer at the top of ocean that is in direct contact with the atmosphere). Reducing the size of the temperature gradient through the skin layer reduces the flux. Thus, if the absorption of the infrared emission from atmospheric greenhouse gases reduces the gradient through the skin layer, the flow of heat from the ocean beneath will be reduced, leaving more of the heat introduced into the bulk of the upper oceanic layer by the absorption of sunlight to remain there to increase water temperature.

    The post is confusing because it seems to imply that heating the skin layer decreases the ocean â?? atmosphere heat flux. It doesnâ??t â?? it increases it. What is decreased is the net flux from the ocean below to the skin layer. The basic principle is very simple â?? more heat incident on the ocean makes it warmer.

    The supposed paradox arises in the fact that there is no obvious way for the heat absorbed in the skin layer to be transported to the warmer ocean below. This idea demonstrates that a little microphysics can be a dangerous thing. What the warmer skin layer does is result in less net conduction to the surface (on account of the smaller gradient) and suppression of convection which would otherwise transport more of the colder skin layer water into the depths (likewise).

  35. 85
    Hank Roberts says:

    Are you drawing that from Pielke Sr.?
    http://climatesci.atmos.colostate.edu/?p=58

  36. 86

    Some odd characters inadvertently made their way into the previous comment. I was trying to say that sensible and latent heat flux from the skin layer to the atmosphere increased due to heating of the skin layer by longwave.

  37. 87
    Alan says:

    RE #59

    And, I have a reasonable suspicion that US, China and Indian coal deposits are destined for synthetic oil and electric power stations. That **certain** increase of CO2 emissions will not be sequestered despite the irrational (self-serving) optimism of coal interests and despairing hopes of some environmentalists. That idea is a non-sequester.

    Thanks for the laugh at the end of that paragraph. Just thought I would point out that we Aussies are also partners in that suspisious club, few countries can dig up large quantities of coal as efficiently we can.

  38. 88
    John L. McCormick says:

    RE # 87

    Alan, I could also describe carbon sequestration as a pipe dream.

    Consider this: US electric power generation stations, in 2005, emitted 2.44 bilion tons of CO2. In volumetric terms that is 1.12 trillion cubic meters of gas, or for US non-metric types, 268 cubic miles of carbon dioxide gas.

    Compare that to 2005 US natural gas shipments of 24 trillion cubic feet. That equates to 163 cubic miles of gas flowing through about 1.4 million miles of natural gas pipelines (American Gas Association).

    Bottom line: capturing, transporting and storing carbon dioxide from current US generating stations would require handling 1.6 times more volume than all US natural gas deliveries via pipelines at least one meter in diameter (consider the rolled steel demand for how many thousands of miles of pipe).

    It is worth repeating: that 1.12 trillion cubic meters of CO2 emissions will increase in volume as more coal plants are added to the US grid. Each year, more CO2 to fill underground caverns. One could imagine the US interior rising as the gas pushes up the land surface.

    Does CO2 sequestration sound like a pipe dream to you?

  39. 89
    Yartrebo says:

    Re #87 and #88:

    That’s not even the half of it. Carbon sequestration reduces the efficiency of the power plant by about 10% and increases the cost per kW*h by about 2 cents (~50% increase) – and the CO2 still has to be shipped and stuffed underground as you mentioned.

    Considering that coal competes on cost, large scale carbon sequestration truly is a pipe dream.

  40. 90

    Sorry for the late drop-by.

    I have two questions about this project:

    - I suppose that the IR waves reflected by clouds has more or less the same spectrum as was emitted by the surface. But is that the same for CO2 re-emitted IR waves (after absorption)?
    - While I am still learning about the behaviour of clouds, clouds are mostly water drops. This means that fine water drops reflect/transmit IR and don’t absorb (much) IR, or they should heat up and disappear. Isn’t that similar for the skin effect of the ocean’s surface?

  41. 91

    How and when will this skin phenomena be incorporated into the models? Since variation in solar forcing is strongly coupled to 10s of meters of the ocean surface, while the above result is proposing that variation in GHG forcing is coupled to the ocean by an intermittent skin effect, climate model sensitivitivities GHG and solar forcings should be different.

    “Independent observational” validations of climate model sensitivities based on paleo climate data have largely been based on the assumption that climate sensitivities to solar and GHG forcing changes will be the same. Given large differences in ocean coupling, I don’t see where the modelers are entitled to this null hypothesis, unless they can reproduce it with models incorporating this intermittent skin phenomena.

    I suspect that climate sensitivity to solar is significantly greater and thus will equilibrate over longer time scales than GHG forcings. Based on the observational studies, the models are probably in the right ball park in their sensitivity to solar forcing, and probably share correlated errors in their handling of GHG forcings that make the model sensitivities to GHG forcings similar to that of solar when their coupling with the ocean and thus the climate sensitivity is lower.

    How do the models handle GHG/ocean coupling currently?

  42. 92
    pete best says:

    So now we know why GHG heat the ocean but by how much and what is the latency relative to land heating?

    I have read around 1 deg C and about 30 years of latency

  43. 93
    Jerry Steffens says:

    Isn’t surface heating (by whatever means) effectively transported downward by wind-driven mixing? (Hence the term, “mixed layer”.)Why so much attention to the penetration depth of radiation?

  44. 94
    Harold D. Pierce, Jr. says:

    To what extent do undersea volcanoes and vents contribute to ocean warming? I did a Google search on “map of active undersea volcanoes and vents” and got zip. We know that there are a great many of these. Is there any estimate of the amount of energy released into the ocean from them and how long it takes the heat to come up to the surface? Since the oceans cover ca. 70% of the earth surface, I would be quite tempted to assume that a substantial contribution to climate change could come directly from undersea ocean heating. It would seem to me that until these data are obtained, we should reserve some judgement on the contribution of GHG to global warming.


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