Harry Potter theory of Boating


Update: For those coming here expecting to read the latest Harry Potter news, this a blog about climate change. Harry Potter is mentioned only to refer to all kinds of magical thinking that people try to come up with to explain the recent global warming.  Please read on how it’s merely basic physics that rules our climate…

Consider a boat at sea. It has both a sail (being dependent on the wind – i.e. natural variation) and an engine (i.e. radiative forcing).

The skipper puts the engine on full blast and steers the boat from, say, Holland to England.

Would anyone wonder whether it’s just the wind that’s pushing the boat over the Canal?

That would be the Harry Potter theory of boating.

Harry Potter theory of climate, part I, starring Mark Serreze, stating:

Climate doesn’t change all by itself. It’s not like the Harry Potter theory of climate, where he flicks his magic wand and the climate suddenly changes. Climate only changes for a reason.

Harry Potter theory of climate, part II, starring Judith Curry, saying the following in response to Serreze’s comments (including the one cited above):

Ouch.  On previous Climate Etc. threads on attribution of 20th century climate change, we have pretty much debunked each of these arguments.

Ouch. Debunked. Who would have guessed? Harry?

Harry Potter theory of climate, part III, starring Susan “shewonk”. She seems to be pulling a Start Wars trick though, since she apparently wrote this story over a year ago:

How did this escape the notice of scientists? Millions of dragons flying around, warming the atmosphere?

Luckily, the radiation energy balance provides a powerful constraint for the global average temperature of the planet (Ramanathan and Feng, 2009).


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37 Responses to “Harry Potter theory of Boating”

  1. Dana Says:

    “On previous Climate Etc. threads on attribution of 20th century climate change, we have pretty much debunked each of these arguments.”

    That doesn’t speak well to the credibility of Climate Etc., since everything Serreze said was correct. But since Curry doesn’t provide any links to support her claims, I guess we’ll have to take her word for it. Who needs peer-reviewed literature when you’ve got your own blog?

    Clearly you’re not taking full advantage of your site here, Bart. You should be proving that the sun and galactic cosmic rays and natural cycles are all driving global warming, too!

  2. sharper00 Says:

    Would anyone wonder whether it’s just the wind that’s pushing the boat over the Canal?

    Ahh but what speed is it going at? How good is the data? What are the uncertainty bars? What about the drag from movement through the water? Can models reproduce that? How good or how fraudulent are they?

    What about the radiation pressure exerted by the sun and cosmic rays? Were they measured in that location at that time? How good is that data? What’s the uncertainty? Where can I download the last 20 years worth in Excel format?

    This is obviously a very wicked problem to solve. There are so many factors and so many complexities that it doesn’t seem like we can say with certainty there’s even enough speed to need your “catastrophic anthropogenic acceleration theory”.

    Besides how you attribute a cause to speed anyway? The motion of the boat at any particular instant might be purely natural so you can’t say there was any non-natural acceleration overall.

    Plus boats have always been accelerating long before there were engines. The Romans got around just fine!

    And that’s why I don’t have to pay my share of the fuel cost to get us here. You can’t prove it got us here.

  3. dhogaza Says:

    Remoras! Don’t forget the remoras attached to the ship, far more powerful than wind or screw …

  4. Eli Rabett Says:

    sharper wins the internets.

  5. willard Says:

    Speed does not exist.

  6. sharper00 Says:

    “Speed does not exist.”

    It’s all the book “Slaying The Water Dragon”. They show picture after picture of different boats and none of them are moving. It even comes with it’s own ruler so you can be a citizen scientist at home.

    You place the book down and measure the position of the boat in the picture one day, do the same the next and try to find the difference. There’s a $1m prize if you can find the speed. Naturally nobody has claimed the money and they would if it existed!

  7. RickA Says:


    Speed is the absolute value of velocity. (grin).

  8. willard Says:

    The idea of an absolute speed rate is nonsensical. Regardless of the fact that enough data exist to compute something analogous to a “global speed” for the boat, neither the level nor the trend in such a statistic would provide any meaningful information about the global velocity of boats.

  9. Bart Says:

    I guess a more complete analogy would be as follows:

    The boat has an engine and a sail. It’s going from the UK to the US at a variable speed. We know that both the wind and the engine can move the boat. The engine propels the boat in the direction of the US (but with an inaccurately known power). The windspeed and -direction are variable, sometime pushing the boat towards the US, sometimes back towards the UK. We have only a crude characterization of the wind, i.e. we know that it has episodes of a certain direction: A component of the wind changes direction every ~11 days; then there’s another component that can be quite strong for a day or two, changing direction a few days later. What we know of the wind is that over the time it takes to cross the Atlantic, it changes direction multiple times. It can be quite forceful for a while, but as far as we know there’s no clear sign in its direction over time (at least for the second half of the trip, where the boat went at its fastest). Therefore it’s hard to tell to what extent it has contributed, if at all, to the movement of the boat from the UK to the US. We know the direction of the engine however. The large uncertainties regarding the wind mean that we can’t say for sure that it had no influence on moving the boat from the UK to the US.

    Even more complete would involve having a second, though weaker engine at the other side of the boat, working against the first engine. The net effect of these two engines is still to propel the boat towards the US.

    Hmm, I guess I just killed the simplicity of my initial analogy…

  10. Roddy Campbell Says:

    And of course we have records of lots of previous boats crossing the Atlantic, in both directions, before engines were invented, detailed records of the (natural) variability of crossing time, and detailed records of wind-speed and direction.

    We can also say that crossing times have been generally speeding up since, ooh, the trough of the LIA, roughly!

  11. Eli Rabett Says:

    Ah but the difference between the minimum time for crossing and the maximum has stayed constant so the theory of decreasing transit times is falsified.

  12. MapleLeaf Says:

    Bart this is wicked, you actually made me laugh out loud, and that is before I read Sharper00’s beautiful post/s.

    Well done folks.

  13. MapleLeaf Says:

    Now can anyone work in the divergence problem? :)

  14. andrew adams Says:

    And of course we have records of lots of previous boats crossing the Atlantic, in both directions, before engines were invented, detailed records of the (natural) variability of crossing time, and detailed records of wind-speed and direction.

    Indeed – therefore we cannot claim that the engine was responsible for the movement of the boat unless we disprove the null hypothesis that it was due to natural causes.

  15. Lars Karlsson Says:

    Indeed, how did the Vikings manage to navigate to the lush meadows of Greenland before there were engines? It is all natural!

  16. TimG Says:


    Is this the R&F 2009 paper:

    Because it does not appear to offer any evidence to support your claim since it starts with the assumption that the IPCC sensitivity estimates are correct.

  17. Bart Says:


    No, that’s the more well known PNAS 2008 paper. I meant the 2009 AE paper:
    Air pollution, greenhouse gases and climate change: Global and regional perspectives
    page 38:

    So the process of the net incoming (downward solar energy minus the reflected) solar energy warming the system and the outgoing heat radiation from the warmer planet escaping to space goes on, until the two components of the energy are in balance. On an average sense, it is this radiation energy balance that provides a powerful constraint for the global average temperature of the planet.

  18. TimG Says:


    That paper still uses an assumed value for CO2 sensitivity. This means it provides no meaningful information if the reader disputes the CO2 sensitivity claims.

  19. Bart Says:


    My point for citing that paper in this post was that is clearly says that climate doesn’t change without a reason (a change in the energy balance). I.e. there is no Harry Potter theory of climate change because that would violate conservation of energy.

    You bring up something else. On that front, the paper shows when taking best estimates of the amount of warming so far, the energy imbalance, climate sensitivity and the net forcing, we obtain an internally consistent picture of what’s happening. It doesn’t “prove” the value of climate sensitivity (with some ill defined standard of proof). To show that it’s wrong, you’d have to come up with a quantitative explanation that does a better job of explaining what’s happening.

  20. toto Says:

    1- Some boats in a fishing village had their motors damaged recently for some reason, and can’t quite sail as fast as they did before (or as fast as other boats).

    2- A researcher interested in reconstructing the history of motor performance over time discovers this phenomenon.

    3- From archive logs, he reconstructs past sailing regimes and conclude that the recent damage is, well, recent. Accordingly, he decides to cut off his reconstruction of motor speed increases at the date where he estimates the damage occurred.

    4- Said researcher publishes his findings in a string of papers over about a decade (including a Nature article), each time painstakingly documenting and describing the apparent decline in motor speeds in his data.

    5- In a vulgarization article for non-scientists, another author wants to summarize the current opinion about the change of motor speed over time. He uses the reconstruction exactly as it should be used (ending it at the same date as the original author) and completes it with historical records of maximum motor speed. He explicitly mentions the use of historical records in the caption of said graph. (there seems to be much confusion about this point)

    6- A prominent curmudgeon selectively rearranges bits and pieces from pilfered correspondence to construct an alternate reality, in which the data was fraudulently altered to fit the Global Anthropogenic Motor Improvement agenda.

    7- Previously reputable scientists swallow it hook, line and sinker, complete with selectively quoted emails and incorrect attribution.

    8- Rest of world sighs, goes on with its business. Motors keep improving.

  21. TimG Says:


    Again, all I see in the paper is the assumption that any inbalance in radiation must be explained with antropogenic factors. It does not show that a portion of the inbalance cannot be due to natural shifts in climate.

  22. Bart Says:


    Can we look forward to you showing how another distribution of contributing factors can provide an even better quantitative description of what’s happening?

  23. Eli Rabett Says:

    So Tim, you do believe in majic. Just waving the wand and saying, it’s “natural factors” gets you nowhere. What natural factors? What evidence do you have that they have had the effect you postulate and, btw, why are the human driven forcings we know about not having the effects our best information says they are.

  24. RickA Says:


    You have placed the burden of proof in the wrong place. It is “natural factors” unless science can prove to the contrary.

    Now it is true that conventional wisdom is currently that the the warming experienced in the last 150 years is due to humans.

    However, this is merely an assumption and a theory – but not scientifically validated yet.

    A lot of evidence is consistent with this theory.
    Like physics (CO2 is a global warming gas and should retain heat).
    The average temperature has gone up by about .85C.

    However, a lot of evidence is not consistent with this theory.
    Like why has sea level rise decelerated?
    Why has the ocean cooled since 2003?
    Why are the models all overstating the temperature trend?

    There has been no conclusive proof either way (yet).

    This is because the increase in temperature has not yet passed beyond the historic natural variation experienced over the last few thousand years.

    So absent an extended period of time with a global temperature above historic natural variation – I would say the burden of proof is on science to prove the warming is not due to natural causes.

  25. Dana Says:

    Oooh RickA, nice Gish Gallop. That one would have made Monckton proud! We’ve debunked all those myths at Skeptical Science if you’re interested. Since the anthropogenic global warming theory is overwhelmingly supported by the scientific evidence, there is no longer any reason to assume the warming is ‘natural’ by default.


  26. sharper00 Says:

    “It is “natural factors” unless science can prove to the contrary.”

    To the “We ain’t paying no stinkin’ motorboat fuel cost” party of course. Once they decide scientists actually know science, which will coincide with someone coming up with a way of dividing the fuel bill in a way they don’t mind, then we get to accept reality.

  27. Eli Rabett Says:

    Yesterday, upon the stair,
    I met a man who wasn’t there
    He wasn’t there again today
    I wish, I wish he’d go away…

    When I came home last night at three
    The man was waiting there for me
    But when I looked around the hall
    I couldn’t see him there at all!
    Go away, go away, don’t you come back any more!
    Go away, go away, and please don’t slam the door… (slam!)

    Last night I saw upon the stair
    A little man who wasn’t there
    He wasn’t there again today
    Oh, how I wish he’d go away

    No one can find the natural causes ghost.

  28. Bart Says:


    The consilience of evidence points to substantial contribution of human activities to the warming. Therefore the burden of proof is on those who want to claim otherwise.

    You’re confusing “burden of proof” with “a logical place to start looking for explanation”: Climate has changed before by natural factors. It thus makes sense to inspect those natural factors and see to what extent they’re responsible. It turns out that that’s a relatively small extent compared to human factors.

  29. RickA Says:


    There is a lot of evidence which points to substantial human induced warming.

    However, there is a lot of evidence which isn’t consistent with this theory also.

    For example, CO2 levels were low (280 ppm or so) during the MWP – so what caused that?

    Recent research seems to show that the MWP was worldwide, or at least very widespread, not caused by CO2 and close to or even higher than the global temperature of today.

    So what caused the MWP?

    How do we know that whatever caused the MWP isn’t also playing a major role in the warming over the last 150 years?

    It is still possible that the recent warming could turn out to be caused by CO2, plus other factors, or even that CO2 is a minor player and the other factors major players.

    So I still think the null hypothesis is that the recent warming is natural, and the burden of proof is on those who disagree.

  30. Dana Says:

    RickA, you seem to have missed the entire point of this post. To extend the analogy, the fact that boats used to be wind-powered doesn’t mean that motors won’t also propel a boat. Or similarly, the fact that lightning strikes can cause a fire doesn’t mean that fires can’t be caused by arson.

    A lot of factors probably contributed to the MWP. Low volcanic activity, the sun, internal variability, etc. How do we know those aren’t causing current warming? Observational data and physics.


  31. Dana Says:

    To extend the analogy yet further, the boat is moving at a high speed. We have an anemometer which tells us the wind speed is almost zero. We can hear the motor running, and the gas gauge is dropping. In short, the data clearly show it’s not natural – the motor is what’s propelling the boat.

  32. sharper00 Says:

    “the motor is what’s propelling the boat.”

    Well you would say that since then I have to pay you money for the fuel. The reality you’re proposing costs me money therefore it’s wrong.

  33. Majorajam Says:

    “Well you would say that since then I have to pay you money for the fuel.”


    “You would say that which I so desperately don’t want to hear- something about drifting aimlessly around the ocean starving to death, blah blah whatever- because, notwithstanding you’d have to chip-in equally for fuel if it was so agreed, you are… uh… scamming us… err… I got it- because the fuel makers also send their kids to college where you teach. So yea. QED bitches.

    Besides, even if we excepted your clearly conflicted uncertainty obfuscating advice, the fuel’s not going to run out for at least a decade or so, and after you discount that exponentially at an appropriate market rate, I mean, what’s the present value of starvation in 10 years anyway? De minimis. Like I said, QED.”

  34. willard Says:

    Motors are so Aristotelian. Popper would say that they’re not falsifiable, Feynman would say that you’re not a scientist if you can’t publicly admit it, let alone a man. And what about Eisenhower!

  35. Marion Delgado Says:

    As Galileo before me, I declare that the reason speed does not exist is that, inside the moving boat, you cannot prove it exists. Simple. But I suspect that, like Galileo, I will be criticized – only proving my point.

  36. jyyh Says:

    Sorry, I didn’t read the whole thread.

    Isn’t it obvious that as there are the Artic High and ITCZ which is a low the boat went south? By the same reason the ice accretes on the equator, which is seen on the increasing height of the sunblocking cumulus-clouds @ tropics, thereby a decrease in the sunblock use is expected to begin soon, so the shares will decrease in value? You see, climate scence may have value prognosticating them market shares. Simple!

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