Kevin and his tricks!

Lucia over at The Blackboard has a couple of recent posts about Kevin Trenberth, called Trenberth’s missing trends and Trenberth’s Trick. These posts refer to a recent article by Kevin Trenberth called has global warming stalled?

So what does Lucia cricise about Kevin’s article? Well Kevin mentions that there are 3 periods in the last 30 years or so (1977-1986, 1987-1996, 2001-2012) where the trend has appeared to be flat and his article includes the following figure. The figure includes three horizontal lines covering the periods when the trend appears flat. What Kevin is trying to illustrate here is that although there are periods with no “warming”, the mean temperatures during these periods are still higher than mean temperatures prior to these periods. These aren’t trend lines, they’re simply horizontal lines representing the mean temperatures during these periods. Maybe Kevin could have made this clearer in his article, but that is still what they are (even Bob Tisdale acknowledges this in the comments to one of Lucia’s posts).

Kevin Trenberth's global temperature figure (credit : Kevin Trenberth)

Kevin Trenberth’s global temperature figure (credit : Kevin Trenberth)


So what is Lucia’s criticism? Well one seems to be that Kevin hasn’t really discussed these trends and hasn’t even pointed out that during 2001-2012 the trend was actually negative. Well, firstly the lines on his figure aren’t trend lines, so criticising him for not discussing them seems a little unfair. Secondly, even though the trend for 2001-2012 is indeed negative (-0.016oC per decade) the error is +-0.186oC per decade. Now it is clear that the trend is most likely almost flat during this period, but to claim that it is negative – given such a large error – is a bit of a stretch.

Another criticism seems to be that we can explain the previous two flat periods as being a consequence of volcanic eruptions that produced some cooling. That we can’t explain the most recent flat period in the same way somehow indicates that this newer period is different and maybe indicative of the start of some kind of cooling trend. Really? That seems a bit of an extrapolation to me. All Kevin was pointing out was that natural variations can indeed produce periods during which the trend will appear flat. Lucia seems to agree with that for the periods 1977-1986 and 1987-1996. Maybe not certain what has produced the apparent flat trend during 2001-2012, but there was certainly a large ENSO event in the late 1990s. Given that all Kevin was trying to illustrate was that the periods during which the trends appear flat are still warmer than previous periods, it seems a little disingenuous to criticise him for not discussing things that weren’t even really relevant to what he was trying to illustrate. Also, if you have criticised climate scientists for a lack of rigour, you can’t really eyeball a couple of volcanoes during previous “flat trend” periods and then claim that you’ve explained why some periods have flat trends.

So, why do I think that Kevin’s article is actually pretty good? Well, when he attempts to answer the question “has global warming stalled?” he says

The answer depends a lot on what one means by “global warming”.

Indeed, I think this is one of the main problems with discussions about global warming. As Kevin himself mentions, for some it is equated to the “global mean temperature”. In my opinion, those who equate global warming with changes to the global mean temperature are simply illustrating that they don’t actually understand the fundamentals. Kevin then goes on to say :

“Warming” really means heating, and so it can be manifested in many ways. Rising surface temperatures are just one manifestation. Melting Arctic sea ice is another. ……. However, most (over 90%) of the energy imbalance goes into the ocean.

To me this is the fundamental point. Global warming simply means an increase in the amount of energy going into the climate system, not necessarily an increase in global surface temperatures. What causes this global warming? Currently the scientific evidence suggests that the increase in greenhouse gases in our atmosphere is reducing the amount of energy that is able to escape from our atmosphere and hence increasing the amount of energy in our climate system (i.e., it increases the difference between the incoming radiative flux and the outgoing radiative flux).

Satellites have actually measured this energy imbalance, so it is not simply some theoretical prediction. Kevin discusses this energy imbalance in quite some detail and even points out that

from 2005 to 2010 the sun went into a quiet phase and the warming energy imbalance is estimated to have dropped by about 10 to 15%.

So, even when the Sun went into a quite phase, the energy imbalance only reduced by 10 to 15%. Kevin finishes the article by saying

So the current hiatus in surface warming is a transient and global warming has not gone away: there is a continuing radiative imbalance at the top of atmosphere. But the global warming is manifested in a number of ways.

That’s why I think this is a good article. Kevin is actually discussing the fundamentals of global warming in quite some detail and quite clearly. To criticise it for a simple illustration indicating that – even during periods when the trend was flat – the mean was higher than during earlier periods, rather misses the fundamental point of the article. If you’re going to criticise an article about global warming it would be best if you made it clear that you understand what the term global warming actually means.

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24 Responses to Kevin and his tricks!

  1. BBD says:

    That’s Lucia for you. That’s how she operates. And the spin amongst “sceptics” is that she is honest, unbiased, truly sceptical etc.

    Complete nonsense.

  2. BBD says:

    And as everybody knows to their weary cost, trying to explain to fake sceptics that variability in surface temperatures doesn’t “refute AGW” is a never-ending task.

    Teh Stupid doesn’t understand what is meant by “the climate system” as opposed to “the troposphere”. And Teh Stupid really doesn’t like OHC because it doesn’t do what Teh Stupid wants it to do. So Teh Stupid makes up lies about it, as every fan of WTFUWT knows all too well.

  3. Rachel says:

    The Trenberth article is really good.

    Myles Allen in an article for the Guardian in March – http://www.guardian.co.uk/environment/2013/mar/20/response-mail-on-sunday-great-green-con-climate-change – corrects David Rose when he talks about the lack of warming by writing, “more accurately, lack of surface warming”.

  4. Indeed. I’m never quite sure that I completely understand what is meant by a strawman argument but it does seem as though the skeptic argument that is made – quite strongly – with regards to variability, is just quite simply the wrong way around. It should be straightforward to explain that the evolution of the global surface temperature anomalies is entirely consistent with natural variability imposed on top of a rising trend and that it is very difficult to explain this without invoking global warming. Instead those who are skeptical keep stating that because you can explain the variability in the temperature anomalies through some kind of natural event this somehow makes it more difficult to invoke global warming – conveniently ignoring the underlying rising trend.

  5. Yes, I saw that article by Myles Allen. Also a good article. Slightly uncertain what to make of his later article that seemed to be suggesting that the only way forward was a pragmatic approach to how to respond to global warming – carbon capture being the only way forward.

  6. Rachel says:

    Yes, I saw that one too. I think it’s probably a good idea to encourage the carbon capture technology as much as possible because I think ultimately we may have to return the atmosphere to 350ppm but whether this means we go full steam ahead digging up every fossil fuel we have is another matter and I’m not so sure about that. There are other problems with fossil fuel use like pollution and also the fact it’s a natural resource that we are depleting at the expense of future generations. I prefer the plan towards a shift to renewables. I don’t have a problem with nuclear either especially next generation nuclear which utilizes the waste.

  7. Yes, I agree that it may well be worth developing the technology. However, like you I think, I see no reason why we shouldn’t also be moving – quickly – towards renewables and I don’t buy the argument that the only way that those in the developing world can progress is through the use of fossil fuels.

  8. Rachel says:

    I think it would be the worst thing to get the developing world dependent on fossil fuels as we are and the people who claim they need the fuels don’t really care about those people. I like to respond with something like, there’s only so much carbon we can emit, the only fair thing to do is to divide this equally among 7 billion people which means that most of the developed world must drastically cut their usage while the poorer countries get to increase their use substantially. Those who say they are concerned about people in the developing world don’t usually like this suggestion.

  9. Absolutely. The other issue is that as far as I can tell if you want to provide power to villages in the developing world, it would seem easier to develop cheaper and more efficient solar panel systems or wind turbines that can simply be taken directly to these villages, than convincing the governments of these countries to build big coal-fired/natural-gas power plants and then having to develop all the additional infrastructure (power lines etc). Clearly, the developing world will need large power systems too (for industry) but small wind turbines or solar panel systems could – it would seem to me – make a big difference to some of the poorest in the world.

  10. Rachel says:

    There is one possible bonus to the solution of carbon capture that Myles Allen suggests. If fossil fuel companies are required to capture every single molecule of CO2 that gets emitted as a result of their activities, it will significantly raise the cost of fossil fuels as an energy source and give a huge economic advantage to sources that don’t emit CO2. If carbon capture continues to remain excessively expensive and difficult then it will effectively wipe the industry out anyway.

  11. I hadn’t considered that but, indeed, it would certainly have the effect you suggest.

  12. Skeptikal says:

    In my opinion, those who equate global warming with changes to the global mean temperature are simply illustrating that they don’t actually understand the fundamentals.

    I suspect that it is you who doesn’t understand the fundamentals. The theory is that CO2 traps heat by returning radiated heat to the ‘surface’ from where it was radiated… not to 20,000 leagues under the sea. If the CO2 theory is true, then Global Mean Temperatures MUST rise by this warming effect. Even if heat is somehow being drawn down into the abyss, the surface temperature must still continue to rise as 30% of the surface is land… and not affected by the ocean’s miraculous ability to steal and hide heat. CO2 levels have continued to rise, so there is even more ‘heat trapping’ CO2 in the atmosphere now than there was a decade ago… yet the temperature record doesn’t reflect that increase at all. The surface warms the atmosphere, so if the atmosphere stops warming then that means there’s no extra heat at the surface to generate that warming…. hence, the missing heat.

  13. No, I think you are the one who is mistaken. Indeed CO2 acts to absorb and remit radiation so preventing some from reaching the top of the atmosphere. However, there is nothing in that process that says all of the energy that is “trapped” must act to heat the surface. Some of the energy is returned back to the surface, but 70% of the surface is water and some of the surface is ice.

    If CO2 theory is true, then it is indeed true that surface temperatures must rise, but this is not simply because of the energy trapped by CO2 in the atmosphere acts to heat the surface. The enhanced concentration of CO2 in the atmosphere produces an energy imbalance in which we receive more energy from the Sun than we lose back into space. To remove this imbalance, the surface temperature needs to rise. This process doesn’t have to happen smoothly and continuously. There’s nothing saying that energy can’t first go into the oceans and then later heat the surface (which indeed appears to happen). If anything, what we see in the temperature record is precisely what would be expected. An underlying warming trend overlayed with variations from various other processes.

    The missing heat refers to the difference between the measurements that tells us how much excess energy is entering the climate system and the measurements telling us where this energy has gone (increased surface temperatures, increased ocean heat content). Until quite recently some of this energy was unaccounted for (missing) until measurements of the deep ocean indicated that it may be absorbing 30% of the excess energy entering the system. It’s real missing energy, not energy missing from the models.

  14. BBD says:

    GAT is indeed rising. The rate of rise is apparently modulated by variability in the rate of ocean heat uptake (which modulates SSTs and so tropospheric warming). Negative aerosol forcing is the other important but poorly quantified variable.

    Land surface temperatures are indeed rising faster than global average temperatures, although atmospheric circulation means that they too are modulated by ocean heat uptake.

    I see no reason to suspect that the author of the OP doesn’t understand the fundamentals.

    You, on the other hand, are clearly shaky.

  15. BBD says:

    Wotts – we crossed.

  16. Well, we both seem to have responded in about the same way at least.

  17. BBD says:

    There’s hope yet.
    ;-)

  18. reasonablemadness says:

    “surface temperature must still continue to rise as 30% of the surface is land… and not affected by the ocean’s miraculous ability to steal and hide heat.”
    Oh my god…
    Every bit of land is affected hugely by the oceans. You should do your homework before lecturing us about fundamentals. It is easily recognizable that you don’t know what you are talking.
    If you would be right, oceanic events like El Nino/La Nina would have almost none or only very little effect on surface temperatures over land. But that is dead wrong. El Nino/La Nina for example have huge effects on land temperatures:

    El Nino Southern Oscillation (ENSO) vs Global Land Surface Air Temperatures

    As any sane person can see, El Nino/La Nina events in the Southern Pacific have a very strong influence even on *global* land temperatures. Many regions in the Americas and in Asia/Australia are strongly influenced in temperature as well as in precipitation by those things.

    So to claim, that oceans have no ability to “steal and hide heat” is clearly wrong on every level. Those events do exactly that: They release heat to the atmosphere or they take (“steal and hide”) heat from the atmosphere into the ocean. And such heat exchange between ocean and atmosphere happens not only at ENSO events, it happens all the time. It happens even in your refrigerator. If one body is warmer/colder than the other, than heat will flow from the warmer body to the colder body. That is why your milk gets cold in the refrigerator and why your glass of coke gets warm, when the surrounding air is warm.

    If you don’t get that, I can’t help you. But please stop lecturing anybody about basic physics.

  19. Can I check who you’re responding to here. I assume it’s Skeptical, but that’s not quite clear from your comment.

  20. Sorry, have worked it out. Was getting slightly confused by the thread there and thought you were responding to my post, rather than to Skeptical.

  21. reasonablemadness says:

    Yeah, I was responding to “Skeptical” (it is very sad that the good word “skeptical” gets dragged in the mud by all those deniers, who are anything, but skeptical). I thought it was clear because I quoted him right at the beginning of my post ;)

    BTW: I just stumbled over your blog and I immediately added it to my favorites ;)

  22. acckkii says:

    Reblogged this on acckkii.

  23. Indeed, it was quite clear – it was just me being tired and confused :-)

    Thanks for the rest of the comment.

  24. Pingback: Another Week of GW News, June 23, 2013 [A Few Things Ill Considered] | Blog Submit

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