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What ocean heating reveals about global warming

Filed under: — stefan @ 25 September 2013

The heat content of the oceans is growing and growing.  That means that the greenhouse effect has not taken a pause and the cold sun is not noticeably slowing global warming.

NOAA posts regularly updated measurements of the amount of heat stored in the bulk of the oceans.  For the upper 2000 m (deeper than that not much happens) it looks like this:


Change in the heat content in the upper 2000 m of the world’s oceans. Source: NOAA

The amount of heat stored in the oceans is one of the most important diagnostics for global warming, because about 90% of the additional heat is stored there (you can read more about this in the last IPCC report from 2007).  The atmosphere stores only about 2% because of its small heat capacity.  The surface (including the continental ice masses) can only absorb heat slowly because it is a poor heat conductor.  Thus, heat absorbed by the oceans accounts for almost all of the planet’s radiative imbalance.

If the oceans are warming up, this implies that the Earth must absorb more solar energy than it emits longwave radiation into space. This is the only possible heat source. That’s simply the first law of thermodynamics, conservation of energy. This conservation law is why physicists are so interested in looking at the energy balance of anything. Because we understand the energy balance of our Earth, we also know that global warming is caused by greenhouse gases – which have caused the largest imbalance in the radiative energy budget over the last century.

If the greenhouse effect (that checks the exit of longwave radiation from Earth into space) or the amount of absorbed sunlight diminished, one would see a slowing in the heat uptake of the oceans. The measurements show that this is not the case.

The increase in the amount of heat in the oceans amounts to 17 x 1022 Joules over the last 30 years.  That is so much energy it is equivalent to exploding a Hiroshima bomb every second in the ocean for thirty years.

The data in the graphs comes from the World Ocean Database.  Wikipedia has a fine overview of this database.  The data set includes nine million measured temperature profiles from all of the world’s oceans.  One of my personal heroes, the oceanographer Syd Levitus, has dedicated much of his life to making these oceanographic data freely available to everyone.  During the Cold war that even landed him in a Russian jail for espionage for a while, as he was visiting Russia on his quest for oceanographic data (he once told me of that adventure over breakfast in a Beijing hotel).

How to deny data

Ideologically motivated “climate skeptics” know that these data contradict their claims, and respond … by rejecting the measurements. Millions of stations are dismissed as “negligible” – the work of generations of oceanographers vanish with a journalist’s stroke of a pen because what should not exist, cannot be. “Climate skeptics’” web sites even claim that the measurement uncertainty in the average of 3000 Argo probes is the same as that from each individual one.  Thus not only are the results of climate research called into question, but even the elementary rules of uncertainty calculus that every science student learns in their first semester.  Anything goes when you have to deny global warming.  Even more bizarre is the Star Trek argument – but let me save that for later.

Slowdown in the upper ocean

Let us look at the upper ocean (for historic reasons defined as the upper 700 m):

Change in the heat content of the upper 700 m of the oceans.  Source: NOAA

And here is the direct comparison since 1980:

Changes in the heat content of the oceans.  Source:  Abraham et al., 2013.  The 2-sigma uncertainty for 1980 is 2 x 1022 J and for recent years 0.5 x 1022 J

We see two very interesting things.

First:  Roughly two thirds of the warming since 1980 occurred in the upper ocean.  The heat content of the upper layer has gone up twice as much as in the lower layer (700 – 2000 m).  The average temperature of the upper layer has increased more than three times as much as the lower (because the upper layer is only 700 m thick, and the lower one 1300 m).  That is not surprising, as after all the ocean is heated from above and it takes time for the heat to penetrate deeper.

Second:  In the last ten years the upper layer has warmed more slowly than before.  In spite of this the temperature still is changing as rapidly there as in the lower layer.  This recent slower warming in the upper ocean is closely related to the slower warming of the global surface temperature, because the temperature of the overlaying atmosphere is strongly coupled to the temperature of the ocean surface.

That the heat absorption of the ocean as a whole (at least to 2000 m) has not significantly slowed makes it clear that the reduced warming of the upper layer is not (at least not much) due to decreasing heating from above, but rather mostly due to greater heat loss to lower down:  through the 700 m level, from the upper to the lower layer.  (The transition from solar maximum to solar minimum probably also contributed a small part as planetary heat absorption decreased by about 15%, Abraham, et al., 2013).  It is difficult to establish the exact mechanism for this stronger heat flux to deeper water, given the diverse internal variability in the oceans.

Association with El Niño

Completely independently of this oceanographic data, a simple correlation analysis (Foster and Rahmstorf ERL 2011) showed that the flatter warming trend of the last 10 years was mostly a result of natural variability, namely the recently more frequent appearance of cold La Niña events in the tropical Pacific and a small contribution from decreasing solar activity.  The  effect of La Niña can be seen directly in the following figure, without any statistical analysis.  It shows the annual values of the global temperature with El Niño periods highlighted in red and La Niña periods in blue.  (Weekly updates on the current El Niño situation can be found here.)

Global surface temperature (average of the three series from NOAA, NASA and HadCRU).  Years influenced by El Niño are shown in red, La Niña influenced years in blue.  Source:  Climate Central, updated figure from the World Meteorological Organization (WMO) p. 15.

One finds that both the red El Niño years and the blue La Niña years are getting warmer, but given that we have lately experienced a cluster of La Niña years the overall warming trend over the last ten years is slower.  This can be thought of as the “noise” associated with natural variability, not a change in the “signal” of global warming (as discussed many times before here at RealClimate).

This is consistent with the finding that reduced warming is not mainly a result of a change in radiation balance but due to oceanic heat storage. During La Niña events (with cold ocean surface) the ocean absorbs additional heat that it releases during El Niño events (when the ocean surface is warm). The next El Niño event (whenever it comes – that is a stochastic process) is likely to produce a new global mean temperature record (as happened in 2010).

Kevin Trenberth, who has recently published a paper on this topic, explains the increased heat uptake in the deep ocean:

The reason for the change is a specific change in the winds, especially in the subtropical Pacific, where the trade winds have become noticeably stronger.  That altered ocean currents, strengthening the subtropical sea water circulation thus providing a mechanism to transport heat into the deeper ocean.  This is related to the decadal weather pattern in the Pacific associated with the La Niña phase of the El Niño phenomenon. 

New results from climate modelling

A study by Kosaka and Xie recently published in Nature confirms that the slowing rise in global temperatures during recent years has been a result of prevalent La Niña periods in the tropical Pacific.  The authors write in the abstract:

Our results show that the current hiatus is part of natural climate variability tied specifically to a La Niña like decadal cooling. 

They show this with an elegant experiment, in which they “force” their global climate model to follow the observed history of sea surface temperatures in the eastern tropical Pacific. With this trick the model is made to replay the actual sequence of El Niño and La Niña events found in the real world, rather than producing its own events by chance.  The result is that the model then also reproduces the observed global average temperature history with great accuracy.

There are then at least three independent lines of evidence that confirm we are not dealing with a slowdown in the global warming trend, but rather with progressive global warming with superimposed natural variability:

1.  Our correlation analysis between global temperature and the El Niño Index.

2.  The measurements of oceanic heat uptake.

3.  The new model calculation of Kosaka and Xie.

Beam me up Scotty!

Now to the most amusing attempt of “climate skeptics” to wish these scientific results away.  Their argument goes like this:  It is not possible that warming of the deep ocean accelerates at the same time as warming of the upper ocean slows down, because the heat must pass through the upper layer to reach the depths. A German journalist put it this way:

Winds can do a lot, but can they beam warm surface waters heated by carbon dioxide 700 meters further down? 

This argument reveals once again the shocking lack of understanding of basic physics in “climate skeptic” circles.  First the alleged problem is lacking any factual basis – after all, in the last decades the upper layer of the oceans has warmed faster than the deeper (even if recently not quite as fast as before).  What is the problem with the heat first warming the upper layer before it penetrates deeper? That is entirely as expected.

Second, physically there is absolutely no problem for wind changes to cool the upper ocean at the same time as they warm the deeper layers.  The following figure shows a simple example of how this can happen (there are also other possible mechanisms).

The ocean is known to be thermally stratified, with a warm layer, some hundreds of meters thick, lying on top of a cold deep ocean (a).  In the real world the transition is more gradual, not a sharp boundary as in the simplified diagram.  Panel (b) shows what happens if the wind is turned on. The surface layer (above the dashed depth level) becomes on average colder (less red), the deep layer warmer.  The average temperature changes are not the same (because of the different thickness of the layers), but the changes in heat content are – what the upper layer loses in heat, the lower gains. The First Law of Thermodynamics sends greetings.

Incidentally, that is the well-known mechanism of El Niño: (a) corresponds roughly to El Niño (with a warm eastern tropical Pacific) while (b) is like La Niña (cold eastern tropical Pacific). The winds are the trade winds.  The figure greatly exaggerates the slope of the layer interface, because in reality the ocean is paper thin.  Even a difference of 1000 m across the width of the Pacific (let’s say 10,000 km) leads to a slope of only 1:10,000 – which no one could distinguish from a perfectly horizontal line without massive vertical exaggeration.

Now if during the transition from (a) to (b) the upper layer is heated by the greenhouse effect, its temperature could remain constant while that of the lower one warmed. Simple classical physics without beaming.

Beam me up Scotty!  There is no intelligent life on this planet.


Tamino provides his usual detailed analysis of the new study by Kosaka and Xie.

Dana Nuccitelli in the Guardian on the same paper with some further interesting aspects that I have not talked about here.

Another important point that is often forgotten in the discussion:  The data hole in the Arctic that explains part of the reduced warming trend (maybe even more than previously thought).

And a reminder:  The warming trend of the 15-year period up to 2006 was almost twice as fast as expected (0.3°C per decade, see Fig. 4 here), and (rightly) nobody cared. We published a paper in Science in 2007 where we noted this large trend, and as the first explanation for it we named “intrinsic variability within the climate system”. Which it turned out to be.

Recent Literature:

Levitus et al. (Geophysical Research Letters 2012). Documentation of the heat increase in the world’s oceans since 1955.  Included are uncertainty analyses, maps of the measurement coverage and many illustrations of the regional and vertical distribution of the warming.

Balmaseda et al. (Geophysical Research Letters 2013) shows among other things that El Niño events are associated with a strong loss of heat from the oceans.  As discussed above, during an El Niño the ocean loses heat to the surface because the surface of the ocean (see Fig. (a) above) is unusually warm.  Further, during volcanic eruptions the ocean cools but for another reason: because volcanic aerosols shade the sun and thus the oceans are heated less than normal.

Guemas et al. (Nature Climate Change 2013) shows that the slower warming of the last ten years cannot be explained by a change in the radiative balance of our Earth, but rather by a change in the heat storage of the oceans, and that this can be at least partially reproduced by climate models, if one accounts for the natural fluctuations associated with El Niño in the initialization of the models.

Abraham et al. (Reviews of Geophysics 2013). Very recent, wide ranging review of temperature measurements in the oceans with a detailed discussion of the accuracy of the data, planetary energy balance and the effect of the warming on sea levels.

158 Responses to “What ocean heating reveals about global warming”

  1. 101
    Jim Larsen says:

    98 Hank R said, “otherwise you’re asking us to go find the review articles in the field and summarize them for you”

    I don’t think so. There are plenty of folks here who already know the answer (to whatever his question was). He’s asking for 30 seconds of help.

  2. 102
    Adam Gallon says:

    “No best estimate for equilibrium climate sensitivity can now be given because of a lack of agreement on values across assessed lines of evidence and studies.”
    Sorry? All previous IPCC reports have included this, why, after more years of work, can this not be done now?

  3. 103
    Hank Roberts says:

    > whatever his question was

    His question appears to sum up to:
    “If [heat is mixing into the] oceans, how precisely is it doing this…. Please be precise about the mechanisms, volumes and timescales …. Where … this change in wind driven interchange happening ….”

    The original post and references answer much of that, but “precisely … be precise”? Maybe not.

  4. 104
    Hank Roberts says:

    Seasonal sea surface cooling in the equatorial Pacific cold tongue controlled by ocean mixing

    James N. Moum, Alexander Perlin, Jonathan D. Nash & Michael J. McPhaden
    Nature 500, 64–67(01 August 2013)

    Here we show the existence of a distinctive seasonal cycle of subsurface cooling via mixing in the equatorial Pacific cold tongue, using multi-year measurements of turbulence in the ocean. In boreal spring, SST rises by 2 kelvin when heating of the upper ocean by the atmosphere exceeds cooling by mixing from below. In boreal summer, SST decreases because cooling from below exceeds heating from above. When the effects of lateral advection are considered, the magnitude of summer cooling via mixing (4 kelvin per month) is equivalent to that required to counter the heating terms. These results provide quantitative assessment of how mixing varies on timescales longer than a few weeks, clearly showing its controlling influence on seasonal cooling of SST in a critical oceanic regime.

  5. 105
    Paul Williams says:

    Church and White 2011 showed the forcing as accumulating compared to the accumulating ocean heat content and land/atmosphere/ice-melt energy accumulation.

  6. 106
    Jim Larsen says:

    103 Hank R says, ” but “precisely … be precise”?”

    LOL. So much depends on word choice. Back on topic, I’ve always been under the impression that a La Nina makes global warming worse as more energy gets stored in the system. Does that mean that the spike we’ll get when El Nino comes back will be a bit worse than without the recent La Ninas?

  7. 107
    Mal Adapted says:

    Hank @98, you may regret referring Mr. Millar to Eric S. Raymond. ESR’s advice to software hackers is excellent, but he apparently hasn’t applied it to his own understanding of climate science:

    I’ve written before about scientific error cascades and the pernicious things that happen when junk science becomes the focus or rationale of a political crusade.

    The worst example of this sort of thing in my lifetime, and arguably in the entire history of science, has been the AGW (anthropogenic global warming) panic. Now that the wheels are falling off that juggernaut, I’m starting to hear ordinary people around me wonder how I knew it was bullshit and hot air so much in advance…

    It seems that knowing how to ask questions doesn’t necessarily lead to enhanced apprehension of reality.

  8. 108
    Hank Roberts says:

    > ESR

    Doesn’t matter.
    Personality doesn’t matter.
    Science isn’t an admiration society.
    What matters is that the article gets cited.

    It’s a method for getting advice; it’s been cited, it’s instructive, worth reading and worth reading about.

  9. 109
    Icarus says:

    “Depends on exactly what is going on. The portion associated with ENSO won’t delay anything – you’d get back to the long term trend once we have a few El Niños. The portion associated with short term forcings (solar, unaccounted-for volcanic aerosols, undercounts of Chinese pollution) will depend on their long term evolution – if they stabilise, you’d get a delay. Any portion associated with a model over-sensitivity would imply a lower trend in the future. – gavin”

    Several studies in recent years have shown an acceleration in the rate of heat accumulation in the oceans. I believe sea level rise has also accelerated a little. I know you have to be cautious but isn’t this a strong indication that the lower rate of surface and lower troposphere warming in recent years is due to natural unforced variability rather than climate forcings? It indicates that there has been no decline at all in the rate of heat accumulation in the climate system as a whole… if I understand things correctly.

  10. 110
    Mal Adapted says:

    Heh. In the climate science context, Raymond’s best advice may be this:

    Don’t rush to claim that you have found a bug error in math or logic

    When you are having problems with a piece of software data analysis, don’t claim you have found a bug an error unless you are very, very sure of your ground. Hint: unless you can provide a source-code patch correct argument that fixes the problem, or a regression test against a previous version cite reliable evidence that demonstrates incorrect behavior clearly contradicts the analysis, you are probably not sure enough.

  11. 111
    Hank Roberts says:

    Isaac Held’s blog #41. The hiatus and drought in the U.S. mentions among other work

    Kosaka and Xie 2013, in which a climate model is manipulated by restoring temperatures to observations in the eastern equatorial Pacific.  I find the excellent fit obtained in that paper compelling, having no free parameters in the sense that this computation was not contemplated while the model, GFDL’s CM2.1, was under development, and the model was not modified from the form in which it was frozen back in 2005.   The explanation for the hiatus must, in appears, flow through the the equatorial Pacific. (I have commented on this paper further here.) These authors mention briefly an important  implication of this connection – the extended drought in the Southern US and the hiatus in global mean warming are related.
    Read the rest …

  12. 112
    James says:

    I have read the post twice but, as a non scientist, I am still struggling.

    Basic questions:

    1. What’s the margin of error on the .04 degree increase.

    2. Is the warming of the oceans only a modern phenomenon? If so, why?

  13. 113
    Anonymous Coward says:

    James (#112) asks:

    “1. What’s the margin of error on the .04 degree increase.”
    Following the link to the source of the article’s figures leads you to figures including error bars:
    Also, the article states: “The 2-sigma uncertainty for 1980 is 2*10^22J and for recent years 0.5*10^22J”
    And 10^22J~=0.004C (assuming the energy is spread over the whole of the oceans) according per Gavin Schmidt (#11 response). Of course the energy is not uniformly spread and neither is the uncertainty. But that’s the assumption that got you 0.04C in the first place…

    “2. Is the warming of the oceans only a modern phenomenon? If so, why?”
    Of course not.
    It stands to reason that the oceans haven’t been that warm in a while but since the average temperature of the whole mass of water is so dependent on circulation (it’s only the surface temperature that’s constrained by its interactions with the atmosphere and space), I suppose a plausible history of that particular value would be very hard to reconstruct. But maybe someone knows better…

  14. 114
    Rob Painting says:

    @112 – the current long-term ocean warming is a result of increased greenhouse gases in the atmosphere. See this Real Climate post: Why greenhouse gases heat the ocean. Of course an increase in output of solar radiation could also warm the surface ocean, however there has been a slight decrease over the last few decades, so that can be ruled out.

    You may now understand why global temperature, i.e. ocean heat content, shows such a strong correlation with atmospheric CO2 over the last 800,000 years – as shown in the ice core records.

    Short-term variations in ocean heat uptake, such as the anomalous deep ocean warming of late, are due to changes in the vertical & horizontal distribution of heat in the ocean – mostly the wind-driven ocean circulation. Much of this is likely natural, however changes in aerosol forcing (say increased sulfate pollution from China up until 2007 – Klimont [2013], and increased emissions from tropical volcanoes) would also be likely to affect the ocean circulation too.

  15. 115
    Hank Roberts says:

    Rate of change makes a difference; we’re causing change far faster than any natural event short of a supervolcano or asteroid impact, and we’re persisting at doing it. The changes include changes in wind patterns — so those are going to change how, where, and when and how much changes about how the upper ocean waves mix surface water. A quick glance for 2013 papers in Scholar:

    try skimming a few of the abstracts in the first few pages and remember you can refine the search as you figure out better words to look for or exclude.

  16. 116
    Dick Veldkamp says:

    #96 Lauri, Limit to Growth

    Unfortunately the hoped for decoupling of economic growth and use of materials seems an illusion:

    Part of the abstract:
    Metrics on resource productivity currently used by governments suggest that some developed countries have increased the use of natural resources at a slower rate than economic growth (relative decoupling) or have even managed to use fewer resources over time (absolute decoupling). Using the material footprint (MF), a consumption-based indicator of resource use, we find the contrary: Achievements in decoupling in advanced economies are smaller than reported or even nonexistent.

  17. 117
    Arne Melsom says:

    @59 (Rob Painting) My comment was regarding the equatorial Pacific, for which the second part of your post is relevant, not the first. As you will note from my initial post (@23), I speculated on what the effect would be if an aspect of climate change turns out to be a shift in the circulation with more frequent La Niñas and less frequent El Niños. But, as implied in my initial post, I really have no good reason to extrapolate the recent clustering of La Niñas into the future. So I absolutely consider your assumption that this clustering is unlikely to last to be much more likely than my thought experiment.

    Regarding the first part of your post, I’m well aware that dynamical forcing can shift the vertical position of isopycnals in the subtropical gyres. But in the absense of a global trend in the surface heat flux, wouldn’t this be a regional phenomenon that would be compensated by a lifting of the isopycnals in other regions? Alternatively, if a deepening of the subtropical gyres gives rise to an increase in the heat stored in this water mass, with a corresponding non-zero trend in the surface heat flux; then I should think that a restoration towards conditions of the past must somehow give rise to a delayed warming of the atmosphere (if the surplus is not somehow lost to space).

  18. 118

    Gail, if you are reading Motl, then there is no point responding to you.

    Good luck, you’ll need it.

  19. 119
    Rob Painting says:

    Arne@117 – Sorry, my bad. My previous comment wasn’t addressed at you, but comment @51.

  20. 120
    MARodger says:

    Gail @118.
    You certainly have linked to a blogger who makes a serious error in judgement. He is way out of his depth. He has problems even with the concept of “average depth of ocean,” which is a worry given he is happy to wield mathematics involving integral calculus. Luckily he doesn’t attempt to use such equations but his reliance on a chum tweeting him the answer he wants suggests his chum is also a bit challenged on the subject of Ocean Heat Content.
    In truth, you don’t have to look very far on the web to stumble upon the answer the blogger was trying to obtain all ready completed for you. If you look, your will note there the bloggers second error (that is before he dissolves into incoherence). He calculates the warming over just the oceans and not the full globe. He is also oblivious to his comparison of a forcing (3.7 W/m^2) with an energy imbalance averaged over many decades. Indeed, he is oblivious to what a fool he makes of himself.

    The value that is perhaps more relevant than that addressed by your innumerate blogger is the present rate of increase in humanity’s positive climate forcing which was running at 0.43W/m^2 per decade to 2010. Comparing such an accumulative rate of increase with the 3.7W/m^2 for a doubling of CO2 – that is worth contemplating.

  21. 121

    Here’s another number for consideration. Ice mass loss in Greenland 2003-2009 as measured by GRACE amounts to 223 +/- 29 Gt/yr. If I did my latent heat calculations right, that’s 10^19 J per year just to melt that much ice. If I did my sums right, that’s about 100 Hiroshimas per second.

    Maybe we should just stick to nuking each other. Can we do a whole lot more harm?

  22. 122
    Hank Roberts says:

    Gail, if you average everything out, you get the average.

    Point is, with ocean heating, when the warm layer not disturbed so much by the wind, that layer stays on top, heat transfers to the atmosphere; when the warm layer is being mixed in more by the wind, less stays in the atmosphere.

    Motls seems to be describing something that doesn’t happen and saying that wouldn’t be a problem.

  23. 123
    John T says:

    As I understand it the ARGO float program kicked off in 1999, only started to give meaningful ocean wide data by 2003 and was completed to planned 3000 ocean wide floats by 2007. My question relates to where ocean temperature data came from pre 2003? And what is its standard deviation? As we are talking about tiny hundredths of a degree measurements I am finding it very difficult to place any significance on pre 2003 data. If someone could please cover this off and explain how pre 2003 data was sourced I’d much appreciate it.

  24. 124
    Hank Roberts says:

    for John T.: Revisiting Historical Ocean Surface Temperatures

    (I put your question in the Google search box and it led me to the RealClimate discussion about that, among other links)

  25. 125

    I have a pair of questions and comments.

    I understood the mechanism related to the change in winds in the
    subtropical Pacific as driver for larger heat storage in the deep ocean
    vs. the upper layers described in the post; in Balmaseda et al. paper
    (doi:10.1002/grl.50382); and discussed several times along the comments
    of this post. -By the way, very interesting summary, as usually here.-
    What worries me is whether this mechanism also works during previous
    hiatus decades (as the 1960s) or not. In Balmaseda et al. paper, they
    show very nicely the changes in the ocean heat content (OHC) since the
    late 1950s and how during the last decade the OHC has substantially
    increased in the deep ocean while in the first 300 and 700 meters it has
    stalled. They relate the current hiatus period at the surface and a
    deeper penetration of the warming into the ocean with changes in the
    trade winds on the subtropical Pacific (intensification). However, these
    changes in the trade winds are only shown from 1970s onwards. Does
    someone known if a similar intensification of the trade winds took place
    during the 1960s explaining then that hiatus period too? And another
    question, why is the hiatus period during the 1960s not reflected in a
    larger heat storage in the deep ocean? Meehl et al., 2011
    (doi:10.1038/NCLIMATE1229) show that with a similar radiative imbalance,
    hiatus periods and non-hiatus periods can occur, and that in the first
    case larger heat storage in the deep ocean takes place. Unfortunately,
    the paper goes into future decades and not into previous decades. I have
    tried to find some radiative forcing time-series to check if during the
    1960s the radiation was balanced, but I haven’t found anything.

    These are my questions, and now just a comment. I agree with
    KrishnaAchutaRao that is inaccurate to say that “deeper than 2000 m not
    much happens”. It’s true that there are less observations and that they
    have received less attention. However, significant warming is being
    observed now not only in the Southern Ocean (Purkey & Johnson 2010), but
    also in the North Atlantic (Kouketsu et al., 2011 (doi:
    10.1029/2010JC006464); ICES Report on Ocean Climate 2011) and in the
    Arctic region (doi: 10.1002/grl.50775).

  26. 126
    Anonymous Coward says:

    Raquel wrote: “What worries me is whether this mechanism also works during previous hiatus decades (as the 1960s) or not.”
    You shouldn’t generalize. Volcanism is thought to have made a comeback in the early 60s after 60 years of relative inactivity (at least as far as the volcanic forcing is concerned).
    Figure 9.17 of the AR5 draft doesn’t show much modelled OHC change in the 60s. Some models have a small increase, others a decrease.

    “I have tried to find some radiative forcing time-series to check if during the 1960s the radiation was balanced”
    Such a time-series would have to be a reconstruction.
    If you mean radiative disequilibrium, I guess this is would be highly model-dependent (like the OHC change).
    If you’re talking about the forcing compared to a preindustrial baseline, you might have a negative forcing during and shortly after the Agung eruption but the decade as a whole of course had a significant positive forcing compared to such a baseline due to the much higher GHG levels.
    There’s a difference because of preindustrial and 1960s temperatures were different.

  27. 127
    Doug Bostrom says:

    John T., see the XBT Network.

    Not to sound nasty but I’m in the same boat with you; my expertise doesn’t permit me to conclude that there is no significance to pre-2003 data. Same basic deal as if my radiologist says that tiny little black spot in the x-ray is something significant. I’m going to disagree? How? Way more importantly, why?

  28. 128
    Wayne says:

    There is one denialist argument that I hear but is not discussed in this post and that is “Only solar energy can warm the oceans.” Perhaps it’s so silly it’s not worth bothering with but it does point to holes in my knowledge. I’ve read the guest post from Peter Minnet but as far as I know the experimental data, while interesting, is not yet part of a peer reviewed study.So I’m not aware of solid evidence that CO2 directly warms the ocean.
    Can someone confirm or correct some things for me? It seems to me that a period where solar energy was entering and then quickly circulated into the depths would leave less IR radiation entering the atmosphere. That would mean less surface warming. Would the lack of cooling be evidence for the additional influence of CO2 et al?
    But as the sun has been been flat in the long term and cooling slightly recently how could it cause a consistent rise in temp if it does act alone? Are there other ways energy can enter the oceans? I’ve seen people say because of the energy imbalance it is obvious GHGs are causing the warming but I still don’t understand how.
    I appreciate any insight that can be provided. Thanks

    [Response: This whole issue is a complete red herring. Energy fluxes into the ocean are a combination of radiative (LW + SW), sensible and latent (and a bunch of small terms associated with rivers, icebergs, sea ice etc.). CO2 changes the LW fluxes directly and the other fluxes indirectly – and the net effect is to increase surface air temperatures over the ocean over what they would have been. That leads to a net heat flux into the surface ocean where it anomalously heats the mixed layer (and circulation slowly diffuses and advects that heat into the deeper ocean). It has almost nothing to do with any ‘direct’ heating of the oceans by CO2 directly, but rather follows from basic conservation of energy once the surface fluxes are modified by the higher CO2. – gavin]

  29. 129

    @126 (Anonymous Coward) Many thanks for your answer. I had some problems uploading my comment (125) to this post, and by the time you saw and answered my comment I had also already found the information that you provide me concerning the radiative forcing. Good to see that I am not missing anything important.

  30. 130
    Wayne says:

    @response to 128
    Thanks Gavin. Much appreciated.

  31. 131
    Radical Rodent says:

    Could someone please offer an accepted definition of the term CAGW?

    [Response: An imaginary concept that is brought forth as an incantation whenever there is a need to ward off the possibility of serious discussion. – gavin]

  32. 132
    Ray Ladbury says:

    Radical Rodent

    CAGW–the last refuge of the lukewarmer after they have exhausted all delusions that the planet isn’t warming or that it is due to anything but CO2. This is when they download the recording from the mothership that says: “Yes we are warming the planet, but it will all be good. La-la-la-la-la…”

  33. 133
    SecularAnimist says:

    As I understand it, CAGW is an acronym for catastrophic anthropogenic global warming.

    Given that multiple catastrophes driven partly if not entirely by anthropogenic global warming have already occurred, I don’t see what is “imaginary” about it.

    Of course, ANY idea about what may happen in the future is, by definition, “imaginary”.

    But given that we have every reason to expect AGW-driven catastrophes to esacalate in both severity and frequency, it doesn’t take much “imagination” to expect that to occur, particularly if business-as-usual consumption of fossil fuels continues for many more years. Indeed, it would take a very active and determined “imagination” to come up with scenarios in which that will NOT occur.

    And if someone insists that the word “catastrophic” in that acronym can only properly refer to GLOBAL catastrophe, not “merely” a multitude of local, national or regional catastrophes, well, there are a number of readily “imaginable” scenarios for AGW-driven global ecological collapse and the mass extinction of most life on Earth that are well within the bounds of scientific plausibility.

  34. 134
    Hank Roberts says:

    > readily “imaginable” scenarios

    Imagination is a wonderful thing.
    It’s gotten us where we are now.

  35. 135
    Patrick 027 says:

    … the “Earth 2100” movie seemed CAGW enough to me (and plausible) – OTOH, if one is thinking of turning Earth into Venus, they’ll have to wait through some serious geologic time before that kind of C becomes likely, so far as I know (see Chris Colose’s info on that) (though I’d really still prefer it to be even later than that, frankly).

  36. 136
    SecularAnimist says:

    Hank Roberts wrote: “Imagination is a wonderful thing. It’s gotten us where we are now.”

    And it’s the only thing that has any hope of getting us out of the mess we are in now.

    I reject the idea that it is somehow inappropriate to acknowledge that catastrophic anthropogenic global warming is not only possible but plausible if we continue with anything close to business as usual consumption of fossil fuels and the other activities that are contributing to ever-increasing GHG emissions.

    And I also reject the notion that “it ain’t catastrophic” unless we are talking about some kind of “Venus effect”. The collapse of human civilization, the agonizing die-off of a large majority of the human population, and even the mass extinction of most life on Earth, are all quite plausible outcomes, and plenty catastrophic enough.

  37. 137
    Hank Roberts says:

    SA illustrates why the PR folks love the word “catastrophe” — when you use it to describe events covering the span from bad weather to extinction, it’s a rather broad brush claim

    > multiple catastrophes … have already occurred
    > …
    > The collapse of human civilization,
    > the agonizing die-off of a large majority …
    > the mass extinction of most life on Earth,
    > are … catastrophic enough.

    The deniers _love_ this language, because their target — selfish shortsighted readers — will think “Hey, we’ve seen a catastrophe and I feel fine — if that was catastrophe, what, me worry?” and they label people as alarmists.

    Bad weather a climate catastrophe, extinction a catastrophe: used that way, the word loses its significance.

    I’m reminded of earthquake magnitudes.

    So far we’ve seen magnitude 2.0 climate consequences.
    Those can’t be distinguished from natural weather extremes.
    Attribution takes hard scientific work.

    Just you wait.

    9.0 and above — Causes complete devastation and large-scale loss of life.
    8.0 — Very few buildings stay up. Bridges fall down. Underground pipes burst. Railroad rails bend. Large rocks move. Smaller objects are tossed into the air. Some objects are swallowed up by the earth.
    7.0 — It is hard to keep your balance. The ground cracks. Roads shake. Weak buildings fall down. Other buildings are badly damaged.
    6.0 — Pictures can fall off walls. Furniture moves. In some buildings, walls may crack.
    5.0 — If you are in a car, it may rock. Glasses and dishes may rattle. Windows may break.
    4.0 — Buildings shake a little. It feels like a truck is passing by your house.
    3.0 — You may notice this quake if you are sitting still, or upstairs in a house. A hanging object, like a model airplane, may swing.
    2.0 — Trees sway. Small ponds ripple. Doors swing slowly. But you can’t tell that an earthquake is to blame.

  38. 138
    Hank Roberts says:

    But I digress. My apology, Gavin, I’ll try to stay on topic.
    Mmmm, herring …

  39. 139
    Radge Havers says:

    Back to CAGW, which isn’t about science or policy so much as it’s about language manipulation. It’s a cynical conflation of what the science says (AGW) with policy implications ( C ) implying that the science is driven by a political agenda. It’s a term of dog whistle art usually presented with sneering stridency so that there’s no missing the all the implied stock associations (ridiculous dirty hippy, chicken little, elitist, blah blah blah) and their pejorative, supposedly self-evident, intent.

  40. 140
    John West says:

    Radical Rodent says:
    ”Could someone please offer an accepted definition of the term CAGW?”

    CAGW or Catastrophic Anthropogenic Global Warming is the acronym used (mostly by those that don’t support taking immediate action on climate change) for the theory (or collection of hypotheses) that attribute most of the observed modern warming to human activities and warn that continuing similar activities (mostly emitting CO2) could result in warming that is dangerous to both civilization and a number of ecosystems. Those that don’t support immediate action on climate change are attempting to get the point across that it’s the “Catastrophic” part that supports the need for “immediate action”. After all, who’s going to expend a large amount of time and effort to curb IAGW (Inconvenient Anthropogenic Global Warming) or BAGW (Beneficial Anthropogenic Global Warming)?

    Personally, I don’t consider the use of the word “catastrophic” as an unfair characterization of the science as communicated by many reputable organizations such as NASA GISS:

    Research Finds That Earth’s Climate is Approaching ‘Dangerous’ Point

    “Based on climate model studies and the history of the Earth the authors conclude that additional global warming of about 1°C (1.8°F) or more, above global temperature in 2000, is likely to be dangerous.”

    However, there is no universal or a scientific criterion that I know of that specifically defines what would constitute a global catastrophe. Certainly most everyone would probably agree that a mass extinction would be a global catastrophe, but what % increase in weather/climate related disasters would constitute a global catastrophe? The answer to that question is probably considerably different among people of differing points of view.

  41. 141
    John West says:

    Wayne says:
    “There is one denialist argument that I hear but is not discussed in this post and that is “Only solar energy can warm the oceans.”

    That’s like saying only the furnace can warm the interior of my home. But adding insulation also increases the temperature inside my home even with the same furnace input. Akin to adding insulation to a home, enhancing the GHE is about retaining more heat in the system not adding more heat input.

  42. 142
    Hank Roberts says:

    > there is no universal or a scientific
    > criterion that I know of that
    > specifically defines what would
    > constitute a global catastrophe.

    Flood stories. Every culture has at least one great one, sometimes more than one.

    Pacific Northwest for example.

  43. 143
    Doug Bostrom says:

    I was going to say that “CAGW” is the squeaking sound emitted by somebody as they are dropped down the bore hole but others handled the question better.

  44. 144
    Michael says:

    In response to John in 140, it seems to me that it may not necessarily be easy to answer the question as posed because of the preponderance of systems driven to conditions of self-organised criticality (SOC). SOC, particularly across interconnected systems, is perhaps not sufficiently addressed in many analyses, even though such phenomena (e.g. avalanche-type phenomena) are ubiquitous. There could, for example, be SOC events reflected in ice sheet dynamics, as oceanic heat transfer destabilises the Antarctic circulation, leading to acelerated ice sheet destabilisation. It would be interesting if those using climate models could clarify if they do observe SOC effects in their simulations, and particularly in simulations in which climate-ocean-ice sheet systems are integrated (if such are available today). This would help clarify (e.g. for policy makers) the degree to which coastal infrastructure (e.g. sewerage systems, petro refineries, nuclear fleet), all of which in themselves could give rise to serious issues under compromise conditions, may require SOC-informed protection strategies. The existence of SOC events in ecological systems, e.g. the ‘avalanche’ spread of wheat fungus (now affecting wheat crops), tree diseases, bat fungus (affecting the insect control services they provide), forest fires, etc, speak to the inherent nonlinear nature of the systems around us, and whose stability and resilience most of us take for granted.

    What is the degree to which SOC is addressed and/or revealed by the extensive, but often thematically-siloed, studies being carried out? Is there a chunk of the climate-change-radar-screen (concerned with nonlinear systems and their interconnections and coupled responses) missing?

  45. 145
    Hank Roberts says:

    By the way, John West’s hammering on the vagueness of ‘catastrophe’ gives an excellent example of someone in difficulty with the meaning of the word — just the kind of thing I was describing at 22 Oct 2013 at 10:39 AM. Thank you for that.

  46. 146
    SecularAnimist says:

    So I take it that the consensus view is that according to our best current scientific understanding, there is no possibility whatsoever of any catastrophic consequences of anthropogenic global warming; therefore to use the word “catastrophic” is irresponsible alarmism;, and therefore the deniers are actually quite right to accuse anyone who suggests that such outcomes are possible of being an irresponsible alarmist.

  47. 147
    Radge Havers says:

    SA, no.

    ‘Catastrophic’ is not scientifically defined in this context, so it’s not a science word. Either you’re missing the resonance in the way this language is used and misused, or you’re making it more difficult than it needs to be. I’m not sure which.

    To put it into perspective for you, contrary to what you may imagine, I think it’s quite possible that the gauge on my internal catastrophe meter has a higher percentage of area marked as a red zone than yours, and that my indicator needle moves up faster and in bigger increments.

    There are no manufacturers’ specs for this, and no reputable climatologist is going to waste good grant money on monitoring my personal catastrophe meter in order to understand the physics of ice shelf collapse, for example.

  48. 148
    Ray Ladbury says:

    Actually, catastrophe does have a mathematical meaning

  49. 149
    Radge Havers says:



    Come to think of it, since you brought it up, it seems a fair question to ask: How integral to current understanding of climate is catastrophe theory?

  50. 150
    Hank Roberts says:

    > So I take it that

    Only if you limit your choice to between black and white.

    You can do that, in many languages — pick two extremes, limit the words used to one from each end, and you’ve got it.

    In German: it’s either gemütlich or Götterdämmerung.

    In English, it’s either copacetic or catastrophic.

    But language is _so_ variegated.

    You could really do better, I think, with a scale at least as expressive as Richter’s.

    The real point is that the damage to the world isn’t just around a 1 or a 2 and it’s going up to 10 (or 11!)

    The point is that the damage to the world is beginning to be detectable — and it’s going up by orders of magnitude, not simple additive steps.

    Catastrophe, catastrophe, catastrophe, catastrophe …

    Inconvenience, life-threatening, massively damaging, catastrophic. There’s four steps for you. Find a few more.

    Words. They are more useful, the more you use (within reason)

    If you get the right words, people may begin to understand.

    Don’t misunderstand me.
    That would be rhetoric.

    We have real problems to deal with. And none of us are likely to live to see the worse half of the consequences we’re helping produce; we’ve barely had hints yet. Inconvenient, troublesome, nasty hints, so far.