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Ocean heat content: latest numbers

Filed under: — gavin @ 16 August 2006

Net ocean heat content changes are very closely tied to the net radiative imbalance of the planet since the ocean component of the climate system has by far the biggest heat capacity. Thus we have often made the point that diagnosing this imbalance through measurements of temperature in the ocean is a key metric in evaluating the response of the system to changes in CO2 and the other radiative forcings (see here).
In a paper I co-authored last year (Hansen et al, 2005), we compared model results with the trends over the 1993 to 2003 period and showed that they matched quite well (here). Given their importance in evaluating climate models, new reports on the ocean heat content numbers are anticipated quite closely.

Recently, a new preprint with the latest observations (2003 to 2005) has appeared (Lyman et al, hat tip to Climate Science) which shows a decrease in the ocean heat content over those two years, decreasing the magnitude of the long-term trend that had been shown from 1993 to 2003 in previous work (Willis et al, 2004) – from 0.6 W/m2 to about 0.33 W/m2. This has generated a lot of commentary in some circles, but in many cases the full context has not been appreciated.

With any new data sets there are a number of questions that must always be asked: Are the measurements really representing what is claimed? (in particular, are there sampling or definitional problems?). Do related data provide some support for the results? If correct, what are the potential causes? and, most importantly, what part of the changes are related to predictable deterministic effects? This last question brings up the issue of model evaluation, because of course, the models can only be expected to reproduce the deterministic long-term component.

Given some of the ongoing discussion, it obviously still needs to be pointed out that year-to-year fluctuations in any of the key metrics of planet’s climate are mostly a function of the weather and cannot be expected to be captured in climate models, whose ‘weather’ is uncorrelated with that in the real world. So claims that two years worth of extra data of any quantity somehow prove or disprove climate models are simply erroneous. Clearly, life would be simpler without weather ‘noise’ cluttering up the system, but this is something that just needs to be dealt with. Dealing with it means paying more attention to long term changes than to short term fluctuations and making sure that enough ensemble simulations are made with the models to isolate the signal from the noise.

Going back to the data, are there any potential problems? Well, as addressed by the authors, this time frame is the period when the ARGO floating profilers really start to be important in improving the coverage of data (look at the difference in coverage in their figure 8 between 2002 and 2005). The profilers have clearly been the best thing to happen to ocean observations in decades. Not using the profilers gives a smaller recent change – but with increased error bars because of the deterioration of the sampling. Additionally, some parts of the ocean, particularly the Arctic are still not being sampled sufficiently. These effects may yet prove to be part of the story.

What about any supporting data? One problem is that if the ocean has lost heat at the suggested rate, then the thermal exapansion part of recent sea level rise should have decreased (i.e. sea level should have dropped). Overall, sea level however has continued to rise unabated according to the altimeter satellites. The only way to reconcile the results would be to have had a sharp compensating increase in freshwater from the ice sheets adding to sea level (from 0.7 mm/yr to 2.9 mm/yr). This is conceivable (though unlikely), but clearly would not be good news!

If however, we assume that the data are reasonably accurate, what could be going on? Some of the changes are clearly due to ocean circulation changes – an increased advection of warm water from the sub-tropical Atlantic to the North for instance, but the biggest contribution are the changes seen in the sub-tropical South Pacific. The heat can either have been subducted below the 700m level (the bottom depth for this analysis), advected sideways (no real evidence for that though), or lost through the surface (either to the atmosphere, or directly out to space). The third possibility is thought the most likely.

This in turn can have had a number of possible causes: ‘natural’ tropical variability – for instance, the winter (DJF) tropical Pacific cooled over these two years, possibly as part of larger-scale ENSO variability. Alternatively, it may be due to a change in the forcings. Possible candidates are an as-yet-unquantified increase in aerosol forcings from Asian sources. These haven’t been included in simulations since the data on emissions aren’t yet in.

On a larger point, the radiative imbalance in the AR4 models is a function of how effectively the oceans sequester heat (more mixing down implies a greater imbalance) as well as what the forcings are. Therefore, there is a variation in that modelled value across the models – some of which are smaller than our reported figure (all are significantly positive though).

A slightly more subtle (and slightly more valid) criticism is that the reported magnitude of decadal variability in the OHC numbers is larger than is seen in most coupled models. Some recent work has shown that sampling may play a role here, but it wouldn’t necessarily be surprising if this was so. Even in our paper last year we stated that earlier reported decadal variations were not well simulated. There is obviously much that remains to be understood about annual to decadal variability, however, it must be remembered that it is only on the longer time scales that we expect the forced signal to dominate over the internal ‘noise’. On this basis the ocean heat content changes remain a good validation of the climate model simulations.


107 Responses to “Ocean heat content: latest numbers”

  1. 51
    Steve Sadlov says:

    RE: #50 – Of course, I must make mention of the seeming paleo correlation between ice ages and expanded arid regions. Not sure which is in the driver’s seat. Consider dust. Does dust, in concert with other factors, trigger ice advances? Fast forward to today. Consider impacts of the “Chinese dust mennace” on the big picture.

  2. 52

    If the loss of heat by the oceans is caused by a change in radiation balance, the primary source of the change should be a change in (mainly tropical) cloud cover.

    There is a strong negative correlation between the solar cycle and (low) cloud cover, but the resulting change in cloud cover from the current solar minimum may not be strong enough to explain the fast change in ocean heat content. Neither is there much change in (cooling aerosol) SO2 emissions in the past years around the equator (China, India), compared to the previous period.

    There were indications of a longer-term decrease in (sub)tropical cloud cover (1985-2000), leading to increased insolation (2-3 W/m2) in that period. This may be reversed in recent years. The earthshine project expects such a stabilisation/reverse since ~2000. But what do cloud measurements indicate for the ocean regions with most cooling?

  3. 53
    L. David Cooke says:

    In reference to 18, 20, 24 and others,

    in regards to hurricane transport of of surface through approximately 80 meters of solar insolation may be supportable by a number of sources. First, the NCDC 250mb NH analysis does indicate an increased aberration of the Northern Jet Stream. Second, the indication of the changes of the Walker ITCZ circulation may be an associative indication of a strong northward movement of the normal ITCZ hydrologic cycle and the saturated adiabatic latent heat release of the tropical water vapor in the higher latitudes. Third, the recent NASA articles indicating the increased high altitude (20-26km) air temperatures above the polar regions. In any case, if there is an indication of polar terrestrial IR emissions into space they should be evident as IR flares near the polar regions and observable using the IRAS or GEOS satellite system.

    Regarding the oceanic change whether this is related to fresh water infusion, satellite orbital aberration, or even an average global air pressure or gravitational aberration remains for further review. I would be much more inclined to believe it is a measurement error when dealing with such fine changes. With longer term measures hopefully more of these issues can be clarified.

    Dave Cooke

  4. 54
    Joel Widenor says:

    RE #43 & #50:

    As an agricultural meteorologist, I wanted to provide some clarification on the linked news story from China. The mention in the story of the city of Chongqing not receiving rain for the past 70 days is inaccurate. This weather station has actually received 4 inches of rain since the beginning of July (~40% of normal). In fact, rains were near normal during May/June, with better than 12 inches of rain falling. It is also worth noting that the mentioned area is on the far western edge of major Chinese growing areas. The main growing areas in the North China Plain and Manchuria have had a very good growing season. There certainly are very dry areas at the moment in growing areas of Australia, Argentina, West Africa, and Russia, while much of the Central U.S. & Europe are starting to see a significant reversal this month of earlier dryness. The scattered problem areas have certainly led to a downturn in global production for some crops, but most are still at relatively high levels versus historical norms.

  5. 55
    Rhampton says:

    RE: #52

    Ferdinand, are you referring to Shaviv’s work on Cosmic Ray Flux and global temperature variance? As I understand it, Knud Jahnke of the Astrophysikalisches Institut Potsdam found major flaws in the analysis.

  6. 56
    L. David Cooke says:

    RE: 52, 55

    I suggest it may not be cloud cover alone. Though in my estimation they play a very large role.

    The condition that Ferdinand mentioned may be more likely related to very small aerosols. I would suggest these small aerosols have a large effect on the saturated adiabatic cooling and heating cycles and the transport of water vapor latent heat poleward. The problems with the clouds is not only the altitude; but also the time of day for various cloud classes. Reflectiveity versus the insolative mid-tropospheric heating that can result versus the tendency to reduce terrestrial IR re-emission into space seem to be the three primary characteristics of clouds in relation to surface and atmospheric temperatures. We also have the issue with the class cloud and the time of day and duration that a class of cloud may be overhead.

    We also have the condition regarding air pressure and the character of the cloud cover during certain cyclonic or anti-cyclonic conditions. In another post Ferdinand suggested that there also is the issue of atmospheric saturation and the temperature in the air column. It appears that there are possibly many contributors related to the variation in SSTs and the 20 Deg. C isotherm depth that have yet to be examined before including the variations beyond basic meterologic issues.

    Dave Cooke

  7. 57

    Re: Rhampton #55, In the past Ferdinand has intended the work of Kristjansson not Shaviv that he cites in this post:

    http://www.realclimate.org/wp-comments-popup.php?p=324&c=1#comment-15797

  8. 58
    Rhampton says:

    Re: 52 “But what do cloud measurements indicate for the ocean regions with most cooling?”

    Geophysical Fluid Dynamics Laboratory general circulation model investigation of the indirect radiative effects of anthropogenic sulfate aerosol
    Journal of Geophysical Resarach, 2005

    …This study uses the GFDL GCM in conjunction with monthly mean sulfate climatology from the MOZART chemistry-transport model and relates cloud droplet number concentrations to sulfate mass concentrations using an empirical relationship [Boucher and Lohmann, 1995]. It predicts an annual global mean first indirect forcing of -1.5 W m-2 from an anthropogenic sulfate burden of 0.59 Tg S. Most of the cooling occurs in norhtern hemisphere (NH), where most anthropogenic sources of aerosol are located. Owing to long-range aerosol transport, higher cloud frequency and susceptibility, the cooling over ocean is stronger than over land, resulting in an ocean-to-land ratio of 1.3. Some of the strongest forcing is located off the coasts of east Asia, Europe, and northeast United States. As a result of persistent marine stratocumulus, the oceanic regions off the west coasts of Africa and North America are responsible for the rest.

  9. 59

    Re #55-57,

    Catched by the speed of the blogosphere…

    Indeed I was referring to Kristjansson (thanks Martin), who indicated a good reverse correlation between low cloud cover and (TOA) solar radiation (but worse for GCR – galactic cosmic rays).

    In the longer term, there was (1985-2000) a decrease of high (cirrus) cloud cover over the (sub)tropics, caused by faster Hadley/Walker cell circulation, leading to more insolation (2-3 W/m2) and more escape of heat to space (~5 W/m2). See the works of Wielicki, 2002 and Chen, 2002. This was expanded by J. Norris, 2005 in time, back to 1952 for sea level clouds and 1971 for land based clouds, and in latitude by surface based cloud observations.

    The change in radiation balance is more heating of the oceans at one side (specifically high in the subtropics, as expected), but more heat released at higher altitudes, thus somewhere acting as a net negative feedback to higher sea surface temperatures.

    Further, the change in radiation balance is huge, some order of magnitude larger than what can be calculated from the theoretical increase in LW reradiation by the increase of GHGs in the same time frame. Even with water vapor feedback, this can not be explained.

    Now we (probably) see some reversal of the previous warming of the oceans. So my first thought was clouds, as these can give huge changes in radiation balance in a short time.

    Regarding fine aerosols, as suggested by David, there are huge increases in industrial activity in SE Asia since 1975, but that is a rather linear expansion, where SO2 emissions are in lockstep with more dirtier aerosols. As far as I know, the rate of increase of the emissions didn’t change much in last years, therefore I don’t think that man-made aerosols are responsible. And I have not read of extreme conditions for natural aerosols (Mongolean desert…) either. But I have to admit that I didn’t digest yet all the links about aerosols that David send to another list (UKweatherworld)…

    The solar-cloud connection is quite real (after two satellite measured sun cycles), but can’t explain the rather fast and huge changes in radiation balance over the previous period. There may be self sustaining internal oscillations which feed the changes in SST / air circulation / cloud cover / radiation balance, back and forth (AMO?). But this needs to be resolved.

  10. 60
    Steve Sadlov says:

    “Some of the strongest forcing is located off the coasts of east Asia, Europe, and northeast United States. ”

    In the case of Asia, one must consider both the Chinese dust storms as well as the many power plants and other industrial facilities burning high sulfur coal with no stack scrubbing whatever.

  11. 61

    Re #58,

    Unfortunately, GCM’s don’t provide data.

    Based on the decrease in SO2 emissions in Europa, there should be a huge difference in temperature increase between less polluted areas and more polluted areas, downwind from the main sources. But that is not measurable, see here.

    Based on the increase of aerosols in SE Asia, one should expect less warming in the NH Indian Ocean than in the SH. But that doesn’t fit reality, see here
    And aerosols off the Chinese coast should induce more reflecting, longer lasting clouds, but there was a decrease of cloud cover in the 30N-30S band with increasing aerosol releases (I have no specific figures for the Eastern Pacific).

    And last but not least: ocean heating is larger for the NH part (if corrected for area), while most anthropogenic aerosols are released in the NH (and most stay there until raining out).

  12. 62
    John L. McCormick says:

    China’s coal-fired electric generation stations emitted 26 million tons of sulfur dioxide in 2005. Prior to the 1990 US acid rain program implementation, American generating stations emitted 24 million tons of SO2 and current emissions are about 10.5 million tons.

  13. 63
    david morgan says:

    Here is what we must assume:

    1.) Conservation of volume (aka sea-level) during energy loss.
    2.) Heat transfer to space without massive heat transfer to intermediate atmosphere.
    3.) Heat transfer to space directly by water vapor. (Seriously?)
    4.) Release of massive amounts of water vapor that then somehow does not behave as a greenhouse gas.

    Or, we could look again at the map on page 11. It is very hard to miss the blue line from the tip of africa to tasmania. This is part of the MOC. In fact, you’ll see the rest of the MOC outlined in red and blue.

    What could cause this? The MOC streams could be diverging and resistance to it increasing as it diverges. As it diverges it mixes with the surrounding water.

    Here is Josh Willis (one of the authors) on the issue:

    “… it is true that transport of heat to deeper layers my be a part of the signal(MOC shutdown), but in my opinion, the magnitude and speed of the cooling are too large to be entirely explained this way. The upper 750 m of the ocean cooled by about 3 x 10^22 J in 2 years. This is equivalent to a heat flux of about 0.48 pW, or a circulation change of 116 Sverdrup * degrees C. The difference in mean temperature above and below 750 m is about 7.7 degree C. That means that in order to achieve a sufficient downward heat flux, the circulation would have to change by 15 Sv, more or less instantaneously, and remain that way for 2+ years. 15 Sv is the same order as the mean magnitude of the overturning circulation itelf. That
    would mean that the entire MOC would have had to have shut down instantaneously in 2003 and remained shut down for the past two years. This conflicts with Harry Bryden’s estimate of the MOC that he published in Nature last year, which he computed to be about 15 Sv. from his hydographic cruise in March of 2004.”

    Sure, but the requirements are much less if you use the much cooler temperature of the deep MOC currents, and not just the “below 750 m” temps.

    Michael Winton has also suggested another possibility. He postulated that upward thermal buoyancy flux induced by surface cooling could become insufficient to overcome the stratifying effect of surface freshening, creating a thermal inversion in the oceans. Visually, it would probably have an effect like the north atlantic as pictured on page 11.

  14. 64

    In addition to the clouds item, J. Norris has a paper in preparation about cloud trends vs. climate change.

    On page 58, there is a calculation of cloud feedback, assuming that the change in cloud cover is solely a response to increased forcing. The net response is -0.8, which is a very strong negative feedback…

    Of course this is the response, if nothing else is influencing cloud properties/cover, but important enough for further investigation.

    The paper in preparation gives a very detailed overview of cloud properties and influence and observed SSTs over time. Of interest are pages 62 and 63, where cloud cover changes roughly coincidence with SST changes.

  15. 65
    ike solem says:

    Okay – back to ‘radiative imbalance’. The only way the Earth can lose heat to space is via radiation, but the redistribution of heat within the oceans, atmosphere and ice sheets can occur via conduction, convetion and radiation. Under steady-state conditions, the total radiation absorbed by the Earth must match the total radiation emitted by the Earth; that’s what radiative balance or imbalance means in the climate literature. This is a very different notion than that of a model of radiative absorption and emission in the atmophere, which is a very specific physical process. See the discussion of the microwave satellite temp. measurements (a major discussion that was initiated by climate skeptics who claimed that the satellite record showed tropospheric cooling), at Realclimate: http://www.realclimate.org/index.php/archives/2005/08/et-tu-lt/

    The internal heat transfer beween the oceans, atmosphere and ice sheets can be modelled far easier than it can be measured, but models need real data for comparison. To account for their results, the authors (Lyman et. al) suggest radiative loss to space, but they also include references relating to warming bottom water, deepening tropical gyre warm bowls, and increased mass loss from the Antarctic and Geenland ice sheets. They acknowledge that the altimetry data seems to contradict the notion of radiative heat loss to space.

    Looking at their global map, it seems that the majority of the cooling was from fairly isolated regions centered around 30N and 30S. One thing I would have liked to see in the paper is a quantitative side-by-side comparison of sea-surface temperatures and upper ocean heat content; all the paper says is that only “a small amount of cooling is observed at the surface, although much less than the cooling at depth” though they do report that it is consistent with 2-yr cooling SST trend – but again, no actual data analysis of the SST trend is reported. This seems sloppy to me, since the SST dataset is far more reliable than the upper ocean heat content dataset, and as far as I can tell the Arctic is underrepresented in the data. The global ice-free ocean seems to exclude the Artic and Antarctic ocean regions, since ARGO floaters wouldn’t be likely to survive the sea ice – which is why remote bottom-moored data collection systems are a good idea, esp. for the Arctic. I’d like to see a global map of SST next to their global map of OHC; that might reveal patterns of interest.

    Limited data from the Arctic and Antarctic (the regions that are expected to warm the fastest and the earliest) means that warming in these regions could have offset the rest of the reported trend. The fact that the cooling trend is reduced when the ARGO data is excluded seems to support this notion.

    Incidentally, I just found that the Reynolds SST weekly report has been removed from the NOAA website: here is the old location: http://www.cdc.noaa.gov/Datasets/reynolds_sst/ I’ve been looking at that on a weekly basis for years, and now it’s suddenly gone? There is something odd going on at NOAA and NWS, as far as I can tell – perhaps the climate denialists have found a new home in the federal government. I’d very much like to know why that page has been removed!

    So, the loss of heat from the upper ocean could be an artifact of undersampling in polar regions. I also don’t understand why the authors didn’t separate out SST’s and apply their statistical method to that dataset as well as to their complete ocean heat dataset. How have SST’s changed in polar regions? Furthermore, their globally averaged depth profile (something I’ve never seen before) of ocean heat content is remarkably devoid of any practical information; a latitudinal display at every 10 degrees would be more useful.

    In general, these datasets are supposed to be made available for analysis by other researchers, and there was no mention in the paper of access to the actual data used. It would be nice to see a global map of data density next to the OHC global data map. While restricting access to raw data is common practice in pharmaceutical industry research, this should definitely not become the standard for climate research.

    Even assuming that the dataset is comprehensive: Considering that the upper-ocean cooling is seen mainly at 30N and 30S, another explanation for this cooling is increased ocean – to – atmosphere heat transfer in these regions (possibly aided by hurricane-mixing of the upper ocean layer, and advection of deeper cold water as a result). If so, then it could be that the heat was lost to space, but given the rapid redistribution of heat in the atmosphere via convection, isn’t it also possible that the heat was transferred to the ice sheets, resulting in increased freshwater runoff to the oceans? What makes this scenario unlikely?

    [Response: One minor point. As far as I understand it, hurricanes actually warm the deeper layers (though they do temporarily cool the surface which adjusts through air-sea exchange very quickly after the storm has passed). This is because even the cooled surface waters that are mixed down are still much warmer than the thermocline waters. - gavin]

  16. 66
    L. David Cooke says:

    Ref #59

    Ferdinand;

    My apologies for stepping in earlier; I was trying to bring into the discussion your earlier comment regarding the effect of lack of saturation in the Arctic regions from UKweatherworld. And to share that I am seeing aerosols as a significant participant; however, not the SO2s as much as the SiO.

    In the period of 2001 through 2004 I had observed a very interesting trend in the character of aerosol precipitants along the Eastern Divide of the Appalachian Ridge. A very fine aerosol that appeared to be almost like talc was faily widespread throughout Western NC. At first I thought it was simply dust due to development work in the area. I hung several tape strips across a wide area of NW N Carolina and got some interesting data not only was the aerosol very fine; but, about 1/2 of the aerosols appeard to have a spherical character to them. As I did not have an outlet to share this information I had simply reserved it as a personal observation.

    It was not until the NASA study regarding the Sahara Dust in Florida that I thought about it again. (I wish I still had those samples.) It made me curious if there might not have been a relationship to the volcanic activity in the Caribbean in the late 90′s and the possible character of the hydrologic cycle in the early 90′s. That most aerosols precipitate out in only a few years was clear; but, what happens to the aerosols that reach the Tropopause and lower Stratosphere if they are very fine? The question became; Is it possible that these very fine aerosols were responsible for the change in the hydrologic cycle in that the state change and the normal saturated adiabatic/adaibatic cycle could be interrupted? And that was the balance of the links I had shared with you in reference to the effects of areosols.

    When you and Ike began discussing the the Energy Imbalance and you mentioned the “missing heat”, it brought back the question of what if there is an interruption to normal water vapor latent heat transfer and it is not corrected in the models? As you are pretty busy I had not thought to pursue this with you earlier; but, here there be an opportunity. Has anyone seen anything that would seem to support my observations?

    (*Note, I had not seen that the Walker circulation had increased, I had seen a study that in the N. Pacific it had decreased about 3%. Later I have seen what appears to be an indication of an increase of northern movement of the air mass what was dominated by the Walker circulation. Coupling this effect with the increasing Arctic Easterlies, the warmish high altitude Polar temperatures, the NH 250mb isotherm analysis indicating an abnormal increased deviation of the Northern Jet Stream (http://nomads.ncdc.noaa.gov:9091/ncep/NCEP ) and the “broken” hydroligic changes all seem to point to a similar process.)

    Dave Cooke

  17. 67
    L. David Cooke says:

    Ref #65

    Ike;

    I have not seen a 30 N/S source for 20 Deg. C content, isothermic and SSTs. However, I have a source for around +/- 8 Deg.: http://tao.noaa.gov/tao/jsdisplay/sel_time_series_ndbc.shtml

    In the Eastern N. Pacific the isotherms are getting shallower and the 20 Deg. C depth apppears to be getting shallower over the last 3 years at a number of buoys. However, it is not universal and depending on latitude can be more or less pronounced. (It appears to be a shallower observation closer to the equator and the further east you measure.)

    Dave Cooke

  18. 68
    llewelly says:

    Incidentally, I just found that the Reynolds SST weekly report has been removed from the NOAA website: here is the old location: http://www.cdc.noaa.gov/Datasets/reynolds_sst/ I’ve been looking at that on a weekly basis for years, and now it’s suddenly gone? There is something odd going on at NOAA and NWS, as far as I can tell

    Ike, I think the Reynolds SST weekly report is still available here . NOAA’s web pages appear to be undergoing extensive re-disorganization. So far, everything I thought was gone, I was able to find in a different place by dropping the right keywords into google, followed by ‘site:noaa.gov’ .

  19. 69
    Steve Bloom says:

    RE #65: The GRACE data makes that unlikely. The total for Antarctica and Greenland is only about 1 mm/yr, still a considerable increase from just a few yesrs ago. Josh Willis thought that other contributions might bring it to 2 mm/yr total.

  20. 70
    Eachran says:

    I find that this particular thread is very interesting – thanks to all.

    A question please.

    I understand that ocean circulation is complicated but I have been trying to find out how much is known about the flows of underground rivers and where they enter the ocean. Significant flows of fresh water are involved : for example, one single source with its outlet in the deep Mediterranean is reputed to have sufficient fresh water to supply the needs of Marseilles. The technology for supply is like capping an oil well – at least that is the way I prefer to look at it.

    It occurred to me that there must be similar flows into all the oceans of the world and particularly from melting ice-caps where temperature changes may have exposed previously blocked outlets. Are there any maps of the flows of this fresh water or any other information on this subject which is readable and reliable please, for a non-expert like me. I can persist with the idea of run-off from land, acting as an umbrella as it were, but it doesnt seem correct to me.

    Help!

  21. 71
    L. David Cooke says:

    Rey Eachran;

    I am actually more familiar with the Florida submarine springs; however, the last link I provided below indicate a number in the Med. as well. I did not find any in the Indian Ocean though there are several references to arabian coastal sources. I would be inclined to expect a large amount in SE Asia; however, I have no references.

    Overall I would not expect these to be a profound effect. Though there is a large volume, most can easily be compared to a large stream or small river. Total ground water including the known major rivers that empty into a saline body is likely less then 3-5% of the total volume that evaporates daily whether from land or oceanic sources. I hope this can assist you in your endevors.

    http://sofia.usgs.gov/publications/ofr/00-158/
    http://fulltext10.fcla.edu/cgi/t/text/text-idx?c=fhp&idno=SF00000190&format=pdf
    http://fga.freac.fsu.edu/gaw/2000/resources/waterpdf/springs.pdf
    http://www.flmnh.ufl.edu/springs_of_florida/submarine.html
    http://water.usgs.gov/ogw/karst/kigconference/pws_submarine.htm
    http://www.jhu.edu/~scor/wg112_article.htm

    Dave Cooke

  22. 72
    Eachran says:

    You are a good man Dave Cooke thanks. I understand your point about evaporation but I was also thinking of the impact on undersea currents, temperature and salinity. I shall read your links and continue. Thanks again.

    Anyone else out there with info all gratefully received.

  23. 73

    This link to the US Geological survey site gives you information about ground water dischare. There is twice as much ground water as there is fresh water. http://ga.water.usgs.gov/edu/watercyclegwdischarge.html In fact all rocks, except for a small section above the water table are saturated. Since water is heavier than oil, when an oil resevoir is penetrated, the water forces the oil out of the ground causing a gusher.

    I think most of the groundwater enters the oceans through seeps driven by osmosis. The salty water draws the fresher water out of the rocks, due to the same process that your skin wrinkles in the bath. The salty fluids in the skin soak up the fresh bath water. See http://www.loc.gov/wiseguide/jun05/toes.html

    I think you will find that salinity near the coasts is lower than that at the same depth further from shore, even at great depth.

  24. 74
    Gary Rondeau says:

    Do the oceans offer an engineering oppertunity?
    “Since the ocean component of the climate system has by far the biggest heat capacity” , I’ve been wondering if the cool waters of the deep ocean could be used to mitigate the effects of global warming for a few centuries until we have really depleated our carbon reserves and the system can begin to recover on its own. As repugnant as it is to suggest engineering solutions for mans’s folly – this is one I haven’t heard bantied about – so please shoot it down! IF cool deep sea water were mixed relentlessly with surface water by some engineering method – (e.g. lots of wave operated pumps and 800m pipes) could that enouromous cool reservoir of water a) mitigate the thermal expansion of the oceans because of the differential in thermal expansion of cold and warm water, and b) cool the atmosphere enough to reduce the other wise expected effects of global warming? My back of the envelope calculation suggests that we should be able to do this for several centuries without warming the deep waters very much while maintaining constant surface water temps. (you need about 100 liters/s/km^2 to cool present forcings)- during which time we kick the carbon habit. Besides all of the horrible unknowns, the biggest problem is pumping that much water up and down.

  25. 75
    Hank Roberts says:

    Gary, prior discussion around here has some numbers on the idea:
    http://www.realclimate.org/index.php/archives/2006/06/geo-engineering-in-vogue/#comment-15112

  26. 76
    Yartrebo says:

    Regarding comment 74: That would be a horrible idea to attempt, even if it is feasible (and using OTEC it might be, since that will actually generate a little usable energy in the process), for at least three very big reasons:

    1 – The colder surface water would mean that far less energy is being lost to space, making the energy imbalance even worse.

    2 – Cold water at the bottom of the ocean holds a lot of dissolved carbon and bringing it to the surface will both acidify surface waters and emit carbon into the atmosphere. The amounts of carbon would be vast, on a scale comparable to current human emissions.

    3 – It would involve messing with the environment on an unprecedented scale, and such things generally cause a lot of other effects which we didn’t even imagine could happen.

  27. 77
    John Stiff says:

    Gentle Scientists,

    Google and my brother brought me to this page. I believe you all have explained the heat loss from the surface of the world’s oceans. Ideas that I thought of (solar cycle now at solar minimum, transfer of heat from the oceans to the atmosphere via recent active hurricane seasons, and ice melt runoff) were all taken.

    One point that was not fully considered was the contribution of the melting of the artic ice sheet. It is not only smaller in area, but thinner as well. This, when added to the contributions of the Antarctic, continental glacier, and Greenland melting should account for the discrepancy.

    It goes without saying that melting ice cools the water.

  28. 78
    Rod Gill says:

    With climate and Greenhouse Gas thoeries of Global warming, it appears to me that of most interest is the interface between the Earth’s atmosphere and space and the flow of radiated heat from the sun, what’s reflected back from Earth’s surface and the consequences of any change in that balance.

    So what do the Astrophysicists suggest? The most compelling arguments to me are from the variablility of the earth’s orbit around the sun and the Sun’s variable output of radiated energy. Based on this, energy of all sorts from the sun is predicted to decrease from now until 2030 when it will slowly increase again.

    Since the oceans are massive heat sinks, they cause delays (around a decade or more) in observed temperature changes from changes in radiated energy from the sun. The slight drop in net ocean heat from 2003-2005 fits what the Astrophysicists predicted some years ago. Some of them have also successfully predicted El Nino phases and some of the recent droughts. This tends to lend a certain amount of credibility from my view point as no other branch of science appears to be able to!

    It would be very interesting, to say nothing of it being potentially very useful if Astrophysicists and Climate Scientists got together for a brain storming session. Is this doable?

    Two links regarding variability of sun’s energy and Earth’s changing orbit:
    http://mitosyfraudes.8k.com/Calen/Landscheidt-1.html
    http://www.ngdc.noaa.gov/stp/SOLAR/solarda3.html

  29. 79

    Re #78 and [[The most compelling arguments to me are from the variablility of the earth's orbit around the sun and the Sun's variable output of radiated energy.]]

    I explained in another thread why the Sun can’t be doing it. To summarize, the Sun simply has not grown enough in luminosity to account for the global warming. Let me know if you want to see the math.

  30. 80

    Re #79,

    Barton, may I disagree? There are two points in this: the sun is since ~1940 higher in intensity than ever in the previous +/- 400 years and probably 8,000 years. This anyway may explain most of the warming in the 1900-1940 period. Second: solar intensity on short term is inversely correlated with low cloud cover (see the reference here), which intensifies the variation and probably the long-term trend too. If the same happens for GHGs remains to be seen (but the trend over the last decades is the other way out for cirrus clouds).

    And even if there is little trend of solar in the past decades (there still is some discussion about an upswing in minimum solar strength), the impact of the higher-than-past level of solar intensity is delayed by the oceans and only now may come into equilibrium…

  31. 81
    Hank Roberts says:

    Ferdinand, have you an explanation in your theory for why none of the other factors act as forcings during the same time period? It sounds like your theory is that somehow only the sun, and nothing else, contributes to the observed change.

    Do you have a way to show that the rest — such as aerosols +co2 +AGHG — somehow sum to zero?

  32. 82
    Hank Roberts says:

    P.S. — I have read http://www.realclimate.org/index.php/archives/category/climate-science/sun-earth-connections/
    and would hope that gets reopened at some point for more discussion.

  33. 83

    Re #81,

    Hank, I never said that CO2 has no influence at all. But I have doubts about the height of the influence, as currently implemented in climate models.

    As already said in previous discussions:
    - the theoretical influence of doubling CO2 is rather well known, based on radiation absorption bands. But that gives less than 1 C warming without feedbacks.
    - the influence of aerosols is highly uncertain and IMHO overestimated. If this is the case, then the influence of GHGs (including feedbacks) is also overestimated, or it is impossible to fit the 1945-1975 temperature trend.
    - the influence of water vapor feedback itself is positive, but clouds seems to act as a strong negative feedback (while current climate models see clouds as a neutral to positive feedback!).
    - the influence of solar variations IMHO is underestimated, as these are accompanied with a positive cloud feedback (and specific influences in the stratosphere).

    This has implications for future scenario’s, as a lower sensitivity for CO2 (and a higher for solar) means that there will be less warming for the same CO2 emissions (assuming no large excursions of solar).
    With halve the sensitivity for CO2 (~1.5 C for 2xCO2, including feedbacks), reduced influence of aerosols (1/4th) and increased solar sensitivity (~1.5 times), one can fit the temperature trend of the last century…

    Based on what I have read about aerosols, cloud behaviour and solar, in my opinion the real response to 2xCO2 may be at (or even below) the low-end scenario of the IPCC…

  34. 84

    Re the Sun — I’ll repeat my calculations here. Please let me know if I made a mistake or mistakes.

    The emission temperature of a planet, the temperature as measured from some distance away, can be found with this equation:

    Te = (S (1 – A) / (4 sigma)) ^ 0.25

    where Te is in kelvins, S is the Solar constant, A the Earth’s bolometric Bond albedo, and sigma the Stefan-Boltzmann constant. S at Earth’s orbit averages 1367.6 Watts per square meter, the Earth’s albedo is about 0.3 (assume this is exact for the moment), and sigma has the value 5.6704 x 10^-8 in the SI, which gives an emission temperature for Earth of 254.9 K.

    Global warming since 1880 or so has been about 0.6 K. How much would the Solar constant have to have risen to provide that much of an increase? Solving for S, we have

    S = 4 sigma Te^4 / (1 – A)

    Plugging our results for Te back into this equation, it gives S = 1367.9 (which shows the problems of using significant digits). If we take Te = 254.9 – 0.6 = 254.3, we get S = 1355.1. In other words, the Solar constant would have to have increased by 12.8 Watts per square meter to get the observed warming. The Solar constant has, in fact, risen by about 1 Watt per square meter over this time period. Solar can’t do it alone without violating conservation of energy.

    Now, there may be some feedback in the Earth system that “multiplies” changes in the Solar constant. But until the Solar freaks identify what that feedback is, their theory fails on basic scientific grounds.

    -BPL

  35. 85

    Re #84,

    Barton,

    What you did forget is to include the greenhouse effect. Of the 1370 W/m2 solar radiation, some 240 W/m2 is reaching the surface. There must be an equilibrium at the TOA, but part of the outgoing radiation from the surface is retained by GHGs, including water vapor. That lowers the ratio between TOA solar radiation and what reaches the surface as solar SW + LW + greenhouse LW.
    This is far better explained by Dr. Scafetta in this RC discussion

    And please reread the solar-cloud connection of fig.1 of Kristjansson, where over a solar cycle (+/- 0.5 W/m2 TOA), the observed change in low cloud cover is within +/- 2%. I have no figures yet what this means in radiation budget (expect some answers in a few weeks). But a change of -1.7% in (high level) clouds over 1 decade caused a change of 1.2 W/m2 in reflected SW and ~3 W/m2 more IR radiation to space over the 30N/S band. Or a pretty significant change in radiation budget…

  36. 86
    Ian Wilson says:

    Has anyone considered the possibility that the Earth’s heat balance is externally driven by a phenomenon related to solar activity.

    Most climatologists limit the solar interaction with climate models to changes in solar insolation. This is understandable, since it is the only form of interaction that is easy to understand and quantify.

    However, it may be possible that slight changes in solar input (eg. UV radiation levels in the stratosphere or cosmic ray influences on low level cloud formation) may be amplified by natural resonance matching to the overall climate system. This may lead to long term heating and warming cycles in the oceans that are the result of upwheling of cool water from deep within the oceans.

    Indeed, historical data shows that about every 30 – 60 years the Nothern Pacific ocean undergoes sustained periods of cooling which by their scale and magnitude must influnece the overall heat balance of the planet.

    Though it still considered very controversial, evidence is emerging that regime changes in the Pacific ocean (the last of which was in 1977) may be caused by small variations in the rotation rate of the Earth that are forced by changes in the level of solar activity.

    [Response: The answer to your first question is, yes, of course. The conclusions from those studies do not support the idea that solar activity (which has been roughly stable since the 1950s) has anything to do with the ongoing rise in temperatures. We are among those climatologists who have explored the intereactions of UV forcing as a mechanism to enhance the solar impact and that is a valid idea (we have some new results which I'm sure you'll find interesting under review at the moment). However, the lack of solar activity trend in recent decades makes it very difficult for any solar mechanism (even unknown ones) to account for the recent climate changes. As to your last point, the idea that Pacific climate is affected by tiny changes in the Earth's rotation is ridiculous (and not controversial at all). The causality is the other way around if there is any connection at all. -gavin]

  37. 87

    Re #85 — well then, please provide a quantitative estimate that refutes my estimate, and explain why it does so. Show your work.

  38. 88
    daCascadian says:

    Ian Wilson >”Has anyone considered the possibility that the Earth’s heat balance is externally driven by a phenomenon related to solar activity…”

    Electromagnetic interactions are certainly a candidate and the contribution of resonances is almost always “underinvestigated”

    “I do not feel obliged to believe that the same God who has endowed us with sense, reason, and intellect has intended us to forgo their use.” – Galileo Galilei

  39. 89
    Enric Palle says:

    Dear all,

    I don’t usually write on internet forums, and neither I like to call attention upon myself. But when talking about the recent cooling of the Earth’s ocean, one of the physical reasons that should immediately pop on our minds are changes in the earth’s reflectance. And there are indeed some indications that the Earth’s albedo has changed in the recent times, in ways consistent with the ocean’s behavior. This is depending on which albedo dataset you are using of course, as they not all agree.

    I would humbly recommend to those interested reading the related discussion on the climate science Pielke’s weblog, and the realclimate thread entitled A cloudy outlook for albedo.

    While the contents on both neither prove nor disprove anything they are certainly food for thought.

  40. 90
    Steve Sadlov says:

    RE: #89 – Ping to the Pielke blog. Indeed, I strongly recommend reading the above linked article.

  41. 91
    Mark A. York says:

    “It sounds like your theory is that somehow only the sun, and nothing else, contributes to the observed change.”

    I’ve been hearing a lot of this lately, but it sounds to me like an either/or fallacy. For some reason some folks want to discount our emissions and inflate some natural megacause. I don’t get it.

  42. 92
    Steve Sadlov says:

    RE: #91 – some of us simply want to understand and account for all components of the energy equations, no agenda aforethought. To allude to an oft overused quote, that which cannot be measured cannot be improved.

  43. 93
    CobblyWorlds says:

    I’ve been following the discussion both here and at Pielke’s Climate Science. Little attention seems to have been paid to the geographical distribution of the changes in figure 2 of Lyman(I think – not got the paper on me). Apologies if this has been answered here – but if it is I’ve somehow missed it (been doing loads of reading to get up to speed on it).

    I assume therefore that we’d expect to see the cooling manifest itself on the Western regions of the Atlantic and Pacific basins, also in a ring around the Antarctic.

    Can someone tell me why this would be expected and would not be a diagnostic?

    Thanks,

    Chris aka Cobblyworlds.

  44. 94
    Hank Roberts says:

    Has anyone read the full text of this recent article from GRL? All I can see is the abstract, and can’t understand it as a nonspecialist. I wondered if it relates to the ocean heat content change described.

    GEOPHYSICAL RESEARCH LETTERS, VOL. 33, L17604, doi:10.1029/2006GL026826, 2006

    Relaxation of central Arctic Ocean hydrography to pre-1990s climatology
    ….
    Abstract:
    _Upper ocean hydrography in the central Arctic Ocean has relaxed since 2000 to near-climatological conditions that pertained before the dramatic changes of the 1990s. The behavior of the anomalies of temperature and salinity in the central Arctic Ocean follow a first-order linear response to the AO with time constant of 5 years and a delay of 3 years._

  45. 95

    Re #87,

    Barton, sorry for the delay (had no Internet access the whole past week)…

    If we accept the figures of Scafetta and West, the practical (observed in different ways) influence of solar changes within the 11 year cycle is ~0.11 K/W/m2 (the W/m2 at the TOA, the K at the surface) and for changes within the 22 year cycle, that increases to ~0.17 K/W/m2. For longer cycles (or non-cyclic trends) this must be substantially higher, as there is no relaxation due to opposite trends in a cycle. Anyway over 0.2 and maybe over 0.5 K/W/m2. Or the increase of 0.6 K over the past century may have been caused for at least for 33% by solar up to maybe over 80%, if one assumes a 1 W/m2 TOA solar energy increase over the past century. But the latter is quite uncertain, as that is based on proxies. We only have real measurements for one 22 year solar cycle…

    That is based on practical evidence, including all feedbacks (thus including cloud feedback). Clouds are such a strong factor in the whole equation, that any theoretical calculation fails if the real feedback of clouds is not included…

  46. 96
    old jim hardy says:

    RE #7 and 18: the missing 10^22 joules — Hurricanes could do that…

    Dad was a hurricane forecaster in Grady Norton’s day. He instilled in me a respect for their order of magnitude.

    Given that a hurricane removes something like 5*10^19 joules per day from the ocean (http://www.aoml.noaa.gov/hrd/tcfaq/D7.html), I too am curious as to hurricanes’ purpose in Mother Nature’s scheme of things. 200 hurricane days in three years is not much of a stretch and it’s all the energy you’re missing. Ten a year at a week apiece…. Have I mis-read that noaa page?

    Looks to me like hurricanes are Mother Nature’s safety valve that blows excess heat right around the insulating layer of GHG, exhausting to the troposphere. From there I assume it’s an easy hop to space.

    I’m an old boiler guy, so the safety valve analogy is natural to me. Others might prefer the analogy of fire sprinklers.

  47. 97
    John L. McCormick says:

    RE #96

    Old Jim Hardy, an interesting post and thanks for the link; helpful facts.

    I like the safety vavle analogy. Makes me think Dr. Lovelock has a keen sense of perception. I am not a Gaia guy, but one can think of the planet using the hurricane, cyclone safety valve to dump excess heat. But, it appears to be limited in its capacity to cool things down.

    As a boiler man, you know the safety valve will keep whistling a bit as the pressure diminishes. If pressure rises again, the safety valve might again come into play. Too much extra heat might overpower the safety valve and chaos ensues. One could say too much extra heat at the earth surface will greatly excite the hurricane safety valve (maybe too much, too often) but not enough heat will be jettisoned to the troposhere and will remain to melt glaciers, warm air currents, disrupt preciptation patterns and, in general, muck up the system

  48. 98
    L. David Cooke says:

    RE: 96

    Dear Mr. Hardy;

    I wanted to thank you for your post. I have been playing here for only a few weeks and there seems to be a loss of familiarity in the data that has been discussed. It was almost a matter of dumbfoundedness after what I had learned in my youth, (From a Miami NHC Eyewall Flight Specialist).

    I reviewed your reference and was amazed to see the logic of old return. Dr. Landsea clearly demonstrated in the FAQ what I thought was apparently news here. (I did not see your reference to the 200 hurricane days in your link; however, what you demonstrated is reasonable.)

    It is kind of amazing that this “new” generation appears to have to start all over again. (See: http://namma.msfc.nasa.gov/index.html ) to learn what the “Gray Heads” have known for decades. I cannot wait to see the new data that they have gathered on this junket.

    Dave Cooke

  49. 99
    Pat Neuman says:

    Dear Old Jim Hardy,

    Under most conditions, the stratosphere puts a lid on heat exhaust from hurricanes in the troposphere making it to outer space. Unlike the troposphere, temperature in the stratosphere increases with height – similar to warm air aloft in the troposphere putting a cap on cloud formation.

  50. 100
    L. David Cooke says:

    RE: #99

    Hey Mr. Newman;

    However, it is quite possible that the Hadley Cell could transport the latent heat to the Ferell cell for exhaust at the Poles. If you look at some of the recent posts on NASA’s Goddard site regarding the upper altitude (@700mb) polar air temperatures and the NCEP NESDIS Jet Stream/Barometric data the transport appears to be possible. It just may be that the transport is occurring at the tropopause or an intermediate layer of around 6-7 Km, based on some recent data coming out of the NAMMA research. (I would possibly keep my eyes on data regarding the Calipso/CloudSat data as well. Just because vertical movement may be limited, a horizontal transport may be available instead. Or put another way, “Just because the door is closed does not mean that an open window is not available.”)

    Dave Cooke


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