Watt about an extended warming plateau?

I know that Sou over at HotWhopper has already covered some of this, so I won’t say much. Anthony Watts has a recent post on Watts Up With That (WUWT) called the warming plateau may extend back even further. The basic premise seems to be that if you remove various natural events (volcanoes, ENSO,…) the trend may end up being flat.

Here’s the very basic physicsy response to this idea. None of these events actually generate energy (even the volcano effect is not because it releases energy, but because it releases sunlight reflecting aerosols). All that these events do is influence how the energy is distributed.

So, if the global surface temperatures are higher now than they were in 1980, the ocean heat content greater than it was in 1980, and the polar ice volume less than it was in 1980, where did the extra energy come from? If someone can convince me that somehow these natural events lead to an increase in global energy, then maybe I’ll start to be convinced. Otherwise, all these natural events are doing is influencing the distribution of energy and something else must be causing the long-term increase in total energy. I’ll let the reader decide what I think that might be.

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19 Responses to Watt about an extended warming plateau?

  1. Wow that’s dumb. Scientists have already removed the noise properly, i.e. Foster & Rahmstorf, Lean & Rind, etc. and they find roughly a 0.17°C per decade surface warming trend results.
    http://www.skepticalscience.com/foster-and-rahmstorf-measure-global-warming-signal.html
    http://www.skepticalscience.com/lean-and-rind-estimate-man-made-and-natural-global-warming.html

    But of course they didn’t use Whitehouse’s patented eyeball method, so I’m sure he’s right and they’re wrong!

  2. Indeed. If I remember correctly, there was criticism of Foster & Rhamstorf et al. from the WUWT crowd because it was seen as fiddling with the data. But it’s okay for them to remove various wiggles and things when it suits them.

  3. indigo says:

    I think you will find that if you remove all the rising temperatures from the dataset, then it can be conclusively shown that temperatures have not risen at all over the last 30 years.

  4. Indeed, if we take out the trend then we find that there’s no trend.

  5. cRR Kampen says:

    ” If someone can convince me that somehow these natural events lead to an increase in global energy” AND show how CO2 is no GHG, then…

  6. climateprediction says:

    Foster and Rahmstorf selected (cherry-picked?) a starting point which is the end of the 1947-1977 flat temperature period. There is no way their conclusions could be true for the 1947-1977 period. Unless the principles of physics changes every 30 years or so, their results don’t pass the logic test. I don’t question that the natural events cited have a significant impact on temperatures. I do question that a sophisticated removal of these impacts will result in the rate of increase CO2 driven increase if the study is extended back to include the flat period.

    Here’s my estimate for the CO2 warming affect. If the temperatures were flat during the 1947-1977 period, then the natural effects totally offset the the CO2 effect. CO2 – natural = 0. Or CO2 = natural. If the natural effects are temporary then a reverse effect should be expected when they oscillate back. If there was a reverse effect during 1977-2007 then only one half of the warming was due to CO2. If this uptrend/downtrend continues, then we would see flat temperatures starting in 2007 for quite some time (30 years?). We are about 20% of the way there.

    I’ve seen several articles about the mysterious global temperature plateau. Maybe its not so mysterious after all. One thing I am sure of. Mother nature isn’t suddenly coming up with new physics equations.

  7. Indeed. Implicit in my statement was that one would need to explain how natural events alone are producing this warming 🙂

  8. I’m not sure that I completely understand what you’re getting at. What physics is giving you the that the supposed reverse effect would imply only half the warming was due to CO2.

    One thing I will say, and maybe I need to stress this a little more, is that global warming is not simply about increasing global surface temperatures. It’s about increasing energy (which was kind of the point of this post). We have satellite measurements that indicate an energy imbalance of between 0.5 – 1 Wm-2. This means an excess of between 2 and 4 x 1021J is entering the climate system. If it’s not increasing global surface temperatures what is it doing? Maybe the satellite measurements are wrong, but if so why? Alternatively, the energy is going somewhere else. Increasing ocean heat content and decreasing arctic ice volume seems consistent with this. Maybe one can question why it’s going there rather than heating the surface, but that doesn’t change that there is a measured energy imbalance and that the increase in ocean heat content and decrease in arctic ice volume is consistent with that imbalance. Given this, and my understanding of basic physics, it would seem much harder to explain how surface temperatures can remain flat for much longer.

  9. Foster and Rahmstorf began their analysis where the satellite temp record begins. There is simply no way to classify that as cherry picking. The mid-century flat temps were also most likely predominantly caused by anthropogenic aerosol emissions.

  10. Skeptikal says:

    If someone can convince me that somehow these natural events lead to an increase in global energy, then maybe I’ll start to be convinced.

    The planet went into the Little Ice Age and then came back out of the Little Ice Age all on its own. Natural variability is a lot more powerful than you give it credit for. That’s real historical evidence that the planet can lose and gain energy all on its own… unless you want to try to deny that the Little Ice Age really happened.

  11. Marco says:

    But we have a good grip on what that “natural variability” was, and we know it isn’t doing anything now. It involved a change in forcings.

  12. Marco’s hit the nail on the head here. We understand the different forcings that can lead to changes in the climate system and can explain a lot (or most) of what has happened in the past through changes in these forcings. Natural doesn’t mean unexplainable or unphysical.

    What I’m suggesting in my statement that you highlight above is not that natural variations can’t influence the climate, but that natural variations can’t increase the total energy in the climate system. Natural variations do not generate energy, they simply move energy around. If the total amount of energy in the climate system is increasing (as it is) you can’t simply claim that it is some kind of natural variation. You have to explain how these natural variations are retaining more of the solar energy today than they were in the past. That’s the problem with simply invoking “natural variations”.

  13. climateprediction says:

    The global temperatures were flat for 30 years during 1947-1977. 60 years prior to that global temperatures declined for a period of roughly 30 years. There was no CO2 growth to offset the decline during that period. And we are currently experiencing a flat period. If the flat or down periods could it extend for 30 years in other times, why not now? Have the physics changed?

    The aerosol theory was put forth to explain the 1947-1977 flat period but it doesn’t explain the drop 60 years before nor the current flat temperatures. There is actually no science to support the aerosol theory. The models just use plug factors to represent this guess because of the lack of science. James Hansen says “aerosol forcing is extremely uncertain” in his January 15th paper and he also notes that the aerosol forcings are just a “guess”.
    http://www.columbia.edu/~jeh1/mailings/2013/20130115_Temperature2012.pdf

    Dana, global temperature data is available before the satellite period. That’s not a good reason for limiting the Foster & Rahmstorf to a period of rapidly rising temperatures. Extending the study back 30 years obviously would change the conclusions. A tricky lot these climate scientists. That’s why it’s good to have a scientist like the host of this site looking over their shoulders, hopefully with a typical scientist’s skepticism.

  14. Pingback: The Climate Change Debate Thread - Page 2712

  15. climateprediction says:

    Let me try again to explain why I believe the observations show that CO2 accounts for less than half the warming attributed to it by the climate scientists without breaking any of the scientific principles you spell out above.

    A recent NY Times article said climate scientists are mystified by the current temperature plateau. They also are mystified by the flat temperatures during the 1947-1977 period. So they “guess” without any scientific support that it was somehow caused by aerosols. They have no explanation for an extended period of falling temperatures some 60 years before.

    Climate scientists also say that Ocean Currents do have significant impacts on global temperatures but they lack the information necessary to model them. That doesn’t mean they have no significant impact.

    Strong La Ninas cause global temperatures to drop a lot. That obviously doesn’t mean they are violating science principles. Strong El Ninos cause the reverse.
    From 2007 until now Multivariate ENSO (MVENSO) has an average reading of -0.3. Another Ocean Current measurement, the Pacific Decadal Oscillation (PDO) has also been in negative over this period averaging -0.7.

    Can these continue in their negative mode for a while longer? Let’s go back to 1947-1977. The MVENSO averaged -0.3 over the entire 30 year period. The PDO averaged -0.6 over the entire 30 year period. Has something changed which would mean this is no longer possible?

    Everyone agrees that Ocean Currents have significant impacts on the climate. Why doesn’t this explanation for the flat temperatures to make sense?

    And what about the intervening 30-year period between 1977 and 2007? Well the MVENSO and the PDO were strongly positive just as they were for the period 60 years prior. Although the MVENSO and PDO data from several decades ago may not be of the same quality as today,s numbers, the positive and negative periods tend to offset one another meaning there is no net energy change which needs to be accounted for.

    So let’s take this one step further. Let’s assume that all the net forcing not due to Ocean Currents is from GHG’s. Then, if temperatures are flat, the Ocean Current forcing equals GHG forcing but in the opposite direction. Then when the Ocean Currents “unwind” in the other direction to get back to the no net energy change position they would logically contribute the same amount of forcing as the GHG’s but in the same direction. The Ocean Currents have no net effect over their full cycle. But GHG’s only contribute half the forcing during the warm periods like 1977-2007 with Ocean Currents contributing the other half. And CO2 which makes up a significant portion of the GHG’s would contribute something little less than half.

    Lastly, let’s take a look at the rapid warming period, 1917-1947. (There are only 2 significant multidecadal periods of warming in the global temperature records, 1917-1947 and 1977-2007.) There was a lot of CO2 added but not as much percentage-wise as in 1977-2007. So if the Ocean Cycle added the same amount of positive forcing as in 1977-2007 but the GHG’s added a little less than the temperature growth rate for 1917-1947 would be expected to be a little lower. The least squares slope for 1977-2007 is 1.7C per 100 years, the comparable statistic for 1917-1947 is 1.4C per 100 years.

  16. I’ll have to give this some more thought, but I do have one quick comment. You refer to forcings from ocean currents. I believe that ocean currents cannot produce a forcing, at least not in the sense that I understand these to be interpreted. The forcings relate to things that can change the net energy flux at the top of the atmosphere. Let’s consider some point in the past when the earth was in equilibrium. Over time, things can change. The solar flux can change. The atmospheric composition can change. If one considers the typical IPCC calculations, what they present are the changes in forcings since 1750. The solar flux has increased by 0.25 Wm-2. Greenhouse gas forcings have increased by about 2.4 Wm-2. Clouds and aerosol forcings are uncertain. Ocean forcing doesn’t come into it.

    Why not? If an ocean current does act to heat the surface, that will increase the surface temperature. If, however, all else remains unchanged and the Earth were in equilibrium prior to the heating of the surface, the radiative flux from the surface would be higher than before; this energy would be lost and the temperature would return to what it was prior to the heating due to the ocean current. This could be seen as some kind of instantaneous forcing, but it’s not a forcing that persists for any length of time and isn’t a forcing that can change the equilibrium surface temperature. That’s essentially the point. The forcings that are of interest are those that can change the equilibrium surface temperature, not effects that can increase the surface temperature without influencing the equilibrium value. That’s why I don’t think ocean currents are particularly relevant to global warming.

  17. climateprediction says:

    I’m not sure whether you are saying that ocean currents cannot cause flat temperatures for 30 years or you are saying that even if they do that is not relevant to global warming if in the next 30 years they “unwind” and contribute the same energy to global warming.

  18. I don’t know if they can cause flat temperatures for 30 years or not. My gut feeling would be no, but I have no evidence for that. My point was more along the lines of the latter part of your comment. It is clear that ocean currents can release energy from the oceans that can heat the surface and hence cause a rise in surface temperatures. Firstly, this isn’t – strictly speaking – a forcing as it doesn’t influence the equilibrium surface temperature.

    Let me see if I can elaborate a little more. If we are undergoing global warming, then that means that we are receiving more energy from the Sun than we lose back into space. If this is true, then the global surface temperature of the Earth must be below the equilibrium value (i.e., the value at which we would be in radiative equilibrium). To reach radiative equilibrium the surface temperature has to rise to this equilibrium temperature. The current picture is that although the surface temperatures have been rising (since the mid 1800s), that we are continuing to release CO2 has meant that we still haven’t reached equilibrium (despite solar forcing only being marginally higher than it was in the late 1800s). Ocean currents could therefore (and probably do) play a role in heating the surface. However, this is just a mechanism through which some of the excess energy ends up heating the surface. It isn’t actually a forcing and – alone – doesn’t explain the rise in surface temperature. If we weren’t undergoing global warming then the influence of the ocean currents should simply be variations around a flat trend (i.e., ocean current would heat the surface to above the equilibrium temperature which would then cool back to equilibrium). That the influence of ocean currents appears to be variations on a rising trend would be what one would expect if we were undergoing global warming.

    Hope I’ve explained that reasonably clearly.

  19. Bernard Murphy says:

    Excellent discussion guy’s, and a pleasure to read. Thanks.

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