Forecasting the Earth’s Temperature
by David Whitehouse via Benny Peiser’s CCnet
The recent spate of scientific papers that are attempting to predict what the earth’s temperature might be in the coming decades, and also explain the current global temperature standstill, are very interesting because of the methods used to analyse temperature variations, and because they illustrate the limitations of our knowledge.
Recall that only one or two annual data points ago many scientists, as well as the most vocal ‘campaigners,’ dismissed the very idea that the world’s average annual temperature had not changed in the past decade. Today it is an observational fact that can no longer be ignored. We should also not forget that nobody anticipated it. Now, post facto, scientists are looking for an explanation, and in doing so we are seeing AGW in a new light.
The main conclusion, and perhaps it’s no surprise, to be drawn about what will happen to global temperatures is that nobody knows.
The other conclusion to be drawn is that without exception the papers assume a constantly increasing AGW in line with the increase of CO2. This means that any forecast will ultimately lead to rising temperatures as AGW is forever upward and natural variations have their limits. But there is another way of looking at the data. Instead of assuming an increasing AGW why not look for evidence of it in the actual data. In other words let the data have primacy over the theory.
Lean and Ride try to isolate and analyse the various factors that affect decadal changes in the temperature record; El Nino, volcanic aerosols, solar irradiance and AGW. Their formula that links these factors together into a time series is quite simple (indeed there is nothing complicated about any of the papers looking at future temperature trends) though in the actual research paper there is not enough information to follow through their calculations completely.
El Nino typically produces 0.2 deg C warming, volcanic aerosols 0.3 deg C cooling on short timescales, solar irradiance 0.1 deg C (I will come back to this figure in a subsequent post) and the IPCC estimate of AGW is 0.1 deg C per decade.
It should also be noted that natural forces are able to produce a 0.5 deg C increase, although over a longer period. The 0.5 deg C warming observed between say 1850 and 1940 is not due to AGW.
The temperature increase since 1980 is in fact smaller than the rise seen between 1850 – 1940, approx 0.4 deg C. This took place in less than two decades and was followed by the current standstill. A fact often overlooked is that this recent temperature increase was much greater than that due to the postulated AGW effect (0.1 deg C per decade). It must have included natural increases of a greater magnitude.
This is curious. If the recent temperature standstill, 2002-2008, is due to natural factors counteracting AGW, and AGW was only a minor component of the 1980 -1998 temperature rise, then one could logically take the viewpoint that the increase could be due to a conspiracy of natural factors forcing the temperature up rather than keeping the temperature down post 2002. One cannot have one rule for the period 2002 – 2008 and another for 1980 -1998!
Lean and Rind estimate that 73% of the temperature variability observed in recent decades is natural. However, looking at the observed range of natural variants, and their uncertainties, one could make a case that the AGW component, which has only possibly shown itself between 1980 – 98, is not a required part of the dataset. Indeed, if one did not have in the back of one’s mind the rising CO2 concentration and the physics of the greenhouse effect, one could make out a good case for reproducing the post 1980 temperature dataset with no AGW!
Natural variations dominate any supposed AGW component over timescales of 3 – 4 decades. If that is so then how should be regard 18 years of warming and decades of standstills or cooling in an AGW context? At what point do we question the hypothesis of CO2 induced warming?
Lean and Rind (2009) look at the various factors known to cause variability in the earths temperature over decadal timescales. They come to the conclusion that between 2009-14 global temperatures will rise quickly by 0.15 deg C – faster than the 0.1 deg C per decade deduced as AGW by the IPCC. Then, in the period 2014-19, there will be only a 0.03 deg C increase. They believe this will be chiefly because of the effect of solar irradiance changes over the solar cycle. Lean and Rind see the 2014-19 period as being similar to the 2002-8 temperature standstill which they say has been caused by a decline in solar irradiance counteracting AGW.
This should case some of the more strident commentators to reflect. Many papers have been published dismissing the sun as a significant factor in AGW. The gist of them is that solar effects dominated up to 1950, but recently it has been swamped by AGW. Now however, we see that the previously dismissed tiny solar effect is able to hold AGW in check for well over a decade – in fact forcing a temperature standstill of duration comparable to the recent warming spell.
At least the predictions from the various papers are testable. Lean and Rind (2009) predict rapid warming. Looking at the other forecasts for near-future temperature changes we have Smith et al (2007) predicting warming, and Keenlyside et al (2008) predicting cooling.
At this point I am reminded that James Hansen ‘raised the alarm’ about global warming in 1988 when he had less than a decade of noisy global warming data on which to base his concern. The amount of warming he observed between 1980 and 1988 was far smaller than known natural variations and far larger than the IPCC would go on to say was due to AGW during that period. So whatever the eventual outcome of the AGW debate, logically Hansen had no scientific case.
There are considerable uncertainties in our understanding of natural factors that affect the earth’s temperature record. Given the IPCC’s estimate of the strength of the postulated AGW warming, it is clear that those uncertainties are larger than the AGW effect that may have been observed.
References:
Lean and Rind 2009, Geophys Res Lett 36, L15708
Smith et al Science 2007, 317, 796 – 799
Keenlyside et al 2008, Nature 453, 84 – 88
Tom P,
Here’s my wager: No one will be able to falsify the theory that global warming/cooling will go outside of its natural historical parameters. We can make the wager for however long you like, up to, say, ten years [I’m in my 60’s and can’t make the wager as long as I’d like].
I’m willing to put up $10,000 cash. Right now.
Anthony can hold the money; winner’s charity gets the loser’s $$$$$ +interest. Winner gets to claim the charitable tax deduction.
What say you, trouserboy?
Agreed?
Tom P (14:45:16) : “If you think the world is warming . . .”
I believe you have subtly shifted what I said. It is not that I think the world is warming, but that I believe that the world has warmed in the past 200+ years, and I do not know if that trend has runned its course or will continue.
Some could quibble with the word “recovered,” but to the extent that the concept of GMT has meaning, it is always in some sort of trend. I have not read the Science article that you referenced, so although I have several questions related to your attached graph, I will forego those until I have a handle on that data splice.
———————–
RW (13:48:22) : “You’ve probably misunderstood what this “RW” character has said. You, and other posters, seem to be under the impression that climate change over any period can be ascribed to one single variable.”
There has been no suggestion or evidence that I misunderstood this “RW” character, and much the contrary, I am the one in those conversations who has emphasized the multitude of variables. And I believe that most posters on this blog have an appreciation for the possible role of many variables. It is the IPCC in AR4 report (and in other places) who have said that the anthropogenic sources that have had overwhelming influence — tossing out natural variables. As I have said before, I do not know whether the set of variables that caused the recovery from the LIA has run its course or whether other variables have emerged to cause a trend in the opposite direction. As a scientist, I have studied more than a dozen proposed key variables in what has caused trends in the past, and CO2 emissions rank toward the bottom of variables that apparently have had a major influence.
Tom P (16:11:41) :
Ron de Haan
It must feel a little demeaning to be scrabbling around with US city data rather than making a global inference.
As you’re talking but not taking, can I infer you’re not willing to put your money where your mouth is?
Tom,
I posted my opinion about Lean and Rind (2009) here: Ron de Haan (10:22:58) :
The link to the icecap.us publication was extra, but interesting.
If the global data is handled like they did with the local data, there would be no AGW Hoax. Read it and you will understand why.
Smokey,
“No one will be able to falsify the theory that global warming/cooling will go outside of its natural historical parameters.”
Are you sure you mean this? This would appear to state that no one will be able to falsify future AGW! In any event, without some quantification of “natural historical parameters” there is no way to determine who might have won a bet based on this statement.
Please try again.
An Inquirer,
“I have not read the Science article that you referenced, so although I have several questions related to your attached graph, I will forego those until I have a handle on that data splice.”
You’ll get a better handle if you first understand that the plot is an overlay of two different independently determined temperature records, not a “data splice”.
Here’s the abstract of the Science article:
Extracting a Climate Signal from 169 Glacier Records
J. Oerlemans
I constructed a temperature history for different parts of the world from 169 glacier length records. Using a first-order theory of glacier dynamics, I related changes in glacier length to changes in temperature. The derived temperature histories are fully independent of proxy and instrumental data used in earlier reconstructions. Moderate global warming started in the middle of the 19th century. The reconstructed warming in the first half of the 20th century is 0.5 kelvin. This warming was notably coherent over the globe. The warming signals from glaciers at low and high elevations appear to be very similar.
[snip]
Ron de Haan,
You certainly appeared to make your intentions clear earlier:
“I don’t know what the future will bring but if I am aloud to gamble, I say we will continue to cool.”
Why the loss of nerve? At least you’re not alone – not one person who has claimed here that the world is cooling has so far been willing to bet on it.
You claim “If the global data is handled like they did with the local data, there would be no AGW Hoax” with reference to:
http://www.crh.noaa.gov/news/display_cmsstory.php?wfo=mkx&storyid=31040&source=0
No, such data would be meaningless. How do you calculate globally “Days with minimum temperatures at or above 70F”? Such a parameter is a local determination and indeed even as such is a useless metric for a good proportion of the globe which never experiences such a high minimum temperature.
I bet. Stop crowing that no one would.
You bet because you believe the odds are in your favor, that there is an unnatural forcing driving up temperatures.
I believe no such thing. But I’m not a Sun worshiper either.
I’d say we have a constrained random walk with a side of Milankovitch. But that is simply my opinion, not some massive logical deduction.
I bet because I think it’s a coin flip, but don’t mind the risk.
So while I haven’t been screaming “It’s cooling”. I clearly disagree with your model and am willing to bet on it.
Leif
“So nobody is really interested in a solution F0 for the Earth (the global average temperature) because it is unphysical e.g doesn’t represent even approximately the physics of the Earth.
Of course it does. Just like it makes a lot of sense to say that the average family has 2 1/3 children. Nothing unphysical about it. The problem comes when you try to make rhetoric out of it.”
.
You still don’t get it do you ?
Or you don’t read what people write ?
In both cases it is a wrong attitude .
So AGAIN :
.
1) There is an infinity of partitions of a surface having the same spatial average temperature .
2) But there is only one partition that solves for the laws of physics .
3) A constant (the average) does NOT solve the laws of physics .
4) A function that violates the laws of physics is unphysical by definition . If you persist to call it physical then it is you who is trying meaningless rhetorics .
5) The only property of the constant is that its integral gives the power . But that is again only a useless tautology because it has been DEFINED that way .
6) The Earth is neither isothermal nor isotropic . A global spatial average can’t have any relevant property for its dynamics even approximately .
See 3) . It has nothing to do with statistics . Have a look at Navier Stokes and live with it .
Charles,
“I bet. Stop crowing that no one would.”
You bet because you are a good sport – full credit to you! But what I actually said was that nobody who had clearly stated they believe the world’s cooling is willing to put their money where their mouth is.
Has there been a sudden conversion to Puritan values by some regular posters to this site?
TomVonk (02:26:22): It has nothing to do with statistics . Have a look at Navier Stokes and live with it.
We know Navier Stokes very well. A mathematician would probably state that strictly speaking there is no such thing as the average temperature for the oceans. Still, if you associate swimming with feeling cold in winter time the reason is that the average temperature is lower in winter time. It has to do with the integration of the partial differential equations over volumes which we physicist call bulk volumes. We then get bulk temperatures,
http://en.wikipedia.org/wiki/Bulk_temperature
Bulk temperatures are real even if the spatial and temporal temperature is not the same all over the bulk. Such bulk temperatures are used in commercial software applications to calculate the transient transport of petroleum fluids in pipelines that are more than 100 kilometers long. The deviation between the simulated and the measured transient fluid temperature after transport through the line is often less than 0,5 degrees Celsius.
While mathematicians cannot live with imprecise definitions like bulk and ocean temperature, these are most useful for physicist and in particular engineers. I suspect that the origin of the problem is that mathematicians are not so trained to do valid approximations based on experimental experience and intuition as physicists and engineers.
Jimmy Haigh (07:45:47) :
“Here’s one for you though, and all you other AGW guys out there. And also to Barrack Obama, Gordon Brown, Angela Merkel, et al.. Why don’t we have a voluntary tax that you pay if you believe AGW is real and you don’t pay if you believe that AGW is a total crock? Seems simple enough to me…”
There already is such a voluntary tax. Some airlines offer the opportunity to buy carbon credits when buying airline tickets. I know of only one person who has ever done this. I understand on good authority that the take up of carbon credits in one airline is tiny. But of course this sample only covers people who do fly and excludes believers such as Mr Gore who presumably don’t……………
TomVonk (02:26:22) :
2) But there is only one partition that solves for the laws of physics .
I don’t know what this statement means. Please explain [and that one only].
Tom P (10:27:13) :
if in 1900 Arrhenius, after he first published the theory that CO2 was warming the atmosphere, had made an identical bet with one of Charles’ ancestors, he would have lost in the first four years but ended up more than $25,000 by the time of his death.
He’d still have been wrong about co2 though. 😉
I already have a $1000 dollar bet running otherwise I’d be tempted. Good luck to you and Charles, but I hope Charles luck is better, both for the sake of his bet and mine.
tallbloke,
I’m curious as to the basis of your existing bet.
It’s a pity you’re unwilling to increase your exposure on this one – the thinking behind my bet is that random fluctuations are damped out when integrated over time, and the stakes increase correspondingly. Hence luck will play a decreasing role as the bet proceeds.
If you’re right the world is cooling there’s every chance to make a sum comparable to what Arrhenius might have won.
Are you sure you’re not tempted?
Tom P: “…nobody who had clearly stated they believe the world’s cooling is willing to put their money where their mouth is.”
It’s interesting that Tom P has re-framed the AGW conjecture to buttress his wager. The actual debate centers on the alarmist contention that runaway global warming will result from added CO2. Global cooling only became an issue when the planet didn’t cooperate with the alarmists’ predictions. With the climate flat to cooling over most of the past decade, the goal posts have been moved again and the new mantra is “global cooling is caused by global warming.” The real response [which they can not face] is: “We were wrong.”
As I’ve pointed out before, TP has set up a stacked deck in his favor by not handicapping the natural global warming trend line. [He also tried to stack the deck by trying to cherry-pick the starting year.] The wager as it stands is close to a 50/50 proposition in the first year. But as time goes on, the wager leans more and more heavily in TP’s favor. He says that anyone declining to play with his stacked deck has no trousers. Could TP be any more insufferable?
I’d be willing to bet that within the next ten years we will never reach the UN/IPCC’s AR-4 projections. But Tom won’t take that bet, because he can’t stack the deck. I’d also be willing to bet the planet will not be 3° C warmer in the next ten years, but of course Tom will come up with various reasons why he won’t fade me. The real reason is the same: he can’t stack the deck.
Trouserboy can offer his wagers and turn down similar wagers from others, there’s no harm in that. But constantly disparaging and ridiculing anyone who doesn’t take his bet, when he has his thumb on the scale all the while, is at best juvenile and it typifies the corruption at the heart of the climate alarmists’ failed conjecture. They have made it personal. And they run and hide from any honest, neutral public debate for the same reason: they can’t stack the deck in their favor.
Alarmists are all pretty much like Tom P, and vice versa. If they can’t win fair and square, they move the goal posts until the odds are in their favor. As the old saying goes, by hook or by crook. Anything to win, right?
Tom P (05:56:43) :
tallbloke,
I’m curious as to the basis of your existing bet.
If you’re right the world is cooling there’s every chance to make a sum comparable to what Arrhenius might have won.
Are you sure you’re not tempted?
It’s a very simple bet. It is that the average temperature for 2015 will be lower than for 2005 as measured by the average of all four major indices.
Looking pretty good at the moment
http://www.woodfortrees.org/plot/wti/from:2005/trend
Temperature is around 0.2C down from 2005 at the moment. 😉
I don’t think that by taking you up on your bet I would gain as much as Fred Bloggs might have in your hypothetical scenario, because I think the game will be up for the AGW hypothesis very soon and you would pull out.
If the negative phases of natural factors can overcome the co2 effect so easily, how much of the late C20th warming was due to the positive phases of those same factors?
tallbloke, Looking at the last 40 year cycle in my posting above, you have a excellent chance of collecting.
Smokey,
There’s no cherry picking of the year. I initially selected 2008 as the starting point early this year simply because it’s the last year we have data for. Coincidentally, the UAH temperature anomaly for 2008, at 0.048 C, is extremely close to the long-term anomaly baseline. Hence, whether you think there is a short term or long term trend in temperatures my starting point is quite reasonable.
Of course the bet is not going to be attractive to anyone who thinks the world is indeed warming. If you have never said the world is cooling, there’s no question of my saying “put up or shut up”. But others certainly have made such a claim. Ron de Haan earlier in this thread indicated he was willing to bet on it. All I did was take such a challenge at face value. The goal posts were well planted before I strode on to the pitch.
As for the other bets subsequently offered, there’s only one that has come up with a clear definition, your 3 degrees increase in the next ten years. We won’t see warming on anything like that scale. Offering a joke bet so as you can claim I’m ducking out reflects rather more poorly on you than me.
I’m all for open and honest debate. But it’s a little difficult to keep this up when as we were last discussing the science you turned rather quiet. Just to remind you what we were looking at:
http://img9.imageshack.us/img9/1994/glaciervsinstrumental.png
A couple of days ago I wrote:
“Hence, unless there is some reason to think the analysis has been fudged – and I have come across no suggestions to that effect – temperature is indeed the main driver for the movement of glaciers. The conclusion is therefore that the overall retreat seen over the last 150 years is due to the global increase in temperature. If you choose to dispute this, please tell me your grounds. If not we can move on.”
I’ve heard nothing back from you. As you have chosen not to dispute this, let’s indeed move on. Maybe you could suggest an explanation for the plot’s shape?
tallbloke,
Here’s the full dataset of temperatures, with the total trend and the trend for 2005 marked out to indicate the starting point:
http://www.woodfortrees.org/plot/wti/from:1978/plot/wti/from:2005/to:2006/trend/plot/wti/from:1978/trend
If I knew nothing about the source of the data, I’d say it was white noise on a rising trend, apart from a couple of excursions. The first of these is an extended below-trend period from 1993 to 1996. The second is a big peak in 1998 to 1999.
In fact we know that the first excursion is the global cooling due to the ash from Mount Pinatubo and the second is the end-of-the-millenium Super El Niño [why do contributors rant on about how global temperature averages are meaningless and don’t reflect the physics of the planet when these features are quite clearly associated with known physical processes?].
Apart from that I can’t really see any other natural factors appearing above the noise, and indeed we are currently above trend.
2005 was a good choice for a starting point – for you! Unlike Smokey I’m not going to fling around baseless accusations of cherrypicking – I’m sure the starting point was chosen as simply as mine. It would have been quite close to the linear trend at the time.
If, again, I was blind to the data source, my best estimate for 2015 would simply be a linear extrapolation – there’s too much noise on this time series to justify a more sophisticated approach. On that basis 2015 should turn out warmer than 2005, though it’s quite close and less than one standard deviation in the noise. Perhaps 60/40 against you.
Obviously I’m no poker player, tipping my hand before making the bet. But if you’re nevertheless willing to increase your exposure I’ll bet against you. As my wager proposal is more impervious to noise than yours, I already have some hedge against random variations in the data.
And Smokey, you owe me quite an apology, as well as a response to my earlier post.
TomP and Smokey
BBC radio 4 at 1.30pm today, Vicky Pope of the Met office reluctantly admits the climate has been cooling against their expectations and models
http://news.bbc.co.uk/1/hi/programmes/more_or_less/8248922.stm#email
tonyb
TonyB,
Just listened to it. She admits nothing like what you said. She states quite clearly that natural variability overlies the long term warming trend that the Met Office model predicts. As a case in point she cites the 1998 El Niño: 1998 was indeed warmer than 2008.
Your hearing was obviously impaired. Were you listening to the programme in the car?
And do you think the world is actually cooling?
TomP
I do not know if this is a transcript of the interview with her, which was a vox pop that fitted into the rest of the programme. She definitely 100% said-very hesistantly in response to the interviewers questioning-that the world had cooled.
You ask me Is the world cooling? Temperatures have been at best flatlining for some years but its much too early to think of it as a trend. I do think ‘global’ temperatures are a nonsense anyway and do not believe we have a reliable measure. This year was the 91st warmest in the CET record. It makes you think…
Personally, if history repeats itself, I would have expected a good more few years of natural warming. I certainly wouldn’t bet on it though and think that sceptics are making themselves hostages to fortune by relying too much on a few years data
By the way the BBC often repeat their programmes (sorry, they give us ‘another chance to hear’) so I will listen out for it.
tonyb
Tom P (10:10:42) :
tallbloke,
Here’s the full dataset of temperatures, with the total trend and the trend for 2005 marked out to indicate the starting point:
2005 was a good choice for a starting point – for you! Unlike Smokey I’m not going to fling around baseless accusations of cherrypicking – I’m sure the starting point was chosen as simply as mine. It would have been quite close to the linear trend at the time.
If, again, I was blind to the data source, my best estimate for 2015 would simply be a linear extrapolation – there’s too much noise on this time series to justify a more sophisticated approach. On that basis 2015 should turn out warmer than 2005, though it’s quite close and less than one standard deviation in the noise. Perhaps 60/40 against you.
Obviously I’m no poker player, tipping my hand before making the bet. But if you’re nevertheless willing to increase your exposure I’ll bet against you. As my wager proposal is more impervious to noise than yours, I already have some hedge against random variations in the data.
Tom, I revisited the terms of my bet, my memory is atrocious at times (Big bike crash 3 years ago). It’s that the trend from 2005-2015 will be down not up. You’d probably say that lowers my chances of winning, but I’m still pretty confident. The guy I bet against has been pretty quiet anyway, which was part of my aim in accepting his bet! 😉
I don’t really want to take on another bet at the moment though, so I’ll decline, sorry.
It’s all good fun though, and by the time the bet matures, the stake will probably buy me and my opponent a rice beer each in some Chinese bar in Europe. All us high rollers should have a get together and a laugh over the whole shenanigans further down the line.
TomP
Sorry Tom, perhaps it was you listening in a car. I just listened again and in response to the inteviewers prompting about the possibility of future ten year cooling periods she says;
‘we’ve just had one’ (a 10 year cooling)
‘yes.’
It is right towards the end of the first item about climate change. Perhaps you fell asleep-the first guy’s voice was very monotonous.
I thought it was a good intelligent programme. I remain to be convinced that the current cooling will turn into a real trend (the MWP lasted 400 years after all) but we have just experienced an extended cooling period which has caused the modellers to come up with new models.
tonyb
TonyB,
Quite correct that there was an admission of a drop. But not that it was against models and expectations – rather that natural variability can occasionally cause such dips.
I agree, though, there’s little cooling trend to be discerned from the data – hence my offer of a bet with tallbloke. But I can’t agree global temperatures are a nonsense – how does the record pick up Pinatubo and El Niño so clearly?
tallbloke,
That’s just as I understood the bet. Shame you’re unwilling to extend, and apologies accepted. I’m just a little miffed though by others who are adamant the world is cooling but are now keeping their mouths shut while their trousers are still round their ankles.
I’ll be on for a beer in 2015 – should I say a warm one?
Smokey,
You’re also keeping very quiet. And it’s you who wrote “they run and hide from any honest, neutral public debate…”