Guest Post by Willis Eschenbach
There’s an old con game that has been played on the suckers for hundreds and hundreds of years. It is done in various forms, with various objects, under various names—three card monty, the shell game, Thimblerig, bottle caps, cups and ball, the game is the same in every one. The essence is, the con man puts a pea under a shell, then switches the shells around and asks which shell is hiding the pea.
Figure 1. The Conjuror, by Hieronymus Bosch, painted 1475-1480. The type of tricks the conjuror is doing are thought to be among the origins of the shell game.
I bring this up because our favorite conjuror, James Hansen, is up to his old tricks again. He has a new paper out, Paleoclimate Implications for Human-Made Climate Change, And as always, you have to figure out which shell is hiding the pea.
Here is his money graph, the one that is getting lots of play around the blogosphere. The main observation I’ve seen people making is that having been bitten by previous failed prognostications, Hansen is taking the well-tested Nostradamus route now, and is predicting sea level rise for when he’ll be 137 years old or so …
Figure 2. Hansen’s Figure 7: ORIGINAL CAPTION: “Five-meter sea level change in 21st century under assumption of linear change and exponential change (Hansen, 2007), the latter with a 10-year doubling time.”
Folks are saying that the bad news is, it looks like we won’t be able to tell until 2040 or so if Hansen’s claim is true. But that’s not the case at all. Those folks are not keeping close enough watch on the pea.
In the paper Hansen says:
Sea level change estimates for 21st century.
IPCC (2007) projected sea level rise by the end of this century of about 29 cm (midrange 20-43 cm, full range 18-59 cm). These projections did not include contributions from ice sheet dynamics, on the grounds that ice sheet physics is not understood well enough.
Rahmstorf (2007) made an important contribution to the sea level discussion by pointing out that even a linear relation between global temperature and the rate of sea level rise, calibrated with 20th century data, implies a 21st [century] sea level rise of about a meter, given expected global warming for BAU greenhouse gas emissions. …
… Hansen (2005, 2007) argues that amplifying feedbacks make ice sheet disintegration necessarily highly non-linear, and that IPCC’s BAU forcing is so huge that it is difficult to see how ice shelves would survive. As warming increases, the number of ice streams contributing to mass loss will increase, contributing to a nonlinear response that should be approximated better by an exponential than by a linear fit. Hansen (2007) suggested that a 10-year doubling time was plausible, and pointed out that such a doubling time, from a 1 mm per year ice sheet contribution to sea level in the decade 2005-2015, would lead to a cumulative 5 m sea level rise by 2095.
The short version of that is:
• The IPCC predicts sea level rise of about a foot (30 cm), but they don’t take ice into account.
• Rahmstorf says a linear projection gives about a metre (3.3 feet) of sea level rise.
• Hansen 2007 says there’s a missing exponential term in Rahmstorf’s work, because the ice will be melting faster and faster every year.
OK, so Hansen 2011 rests on the claims made in Hansen (2007), which turns out to be Scientific reticence and sea level rise. At the end of Section 4 Hansen says that Rahmstorf estimates a 1-metre sea level rise, but that a non-linear ice melting term should be added to the Rahmstorf rise.
Under BAU [“Business As Usual”] forcing in the 21st century, the sea level rise surely will be dominated by a third term: (3) ice sheet disintegration. This third term was small until the past few years, but it is has at least doubled in the past decade and is now close to 1 mm/year, based on the gravity satellite measurements discussed above. … As a quantitative example, let us say that the ice sheet contribution is 1 cm for the decade 2005–15 and that it doubles each decade until the West Antarctic ice sheet is largely depleted. That time constant yields a sea level rise of the order of 5 m this century.
So to get the final Hansen projection, we need to see what is happening in Rahmstorf, A Semi-Empirical Approach to Projecting Future Sea-Level Rise, paywalled, where we find the following graph of projected sea level rise.
Figure 3. The Rahmstorf estimate of sea level rise, to which Hansen says an exponentially growing ice term should be added.
ORIGINAL CAPTION: Past sea level and sea-level projections from 1990 to 2100 based on global mean temperature projections of the IPCC TAR. The gray uncertainty range spans the range of temperature rise of 1.4° to 5.8° C, having been combined with the best statistical fit shown in Fig. 2. The dashed gray lines show the added uncertainty due to the statistical error of the fit of Fig. 2. Colored dashed lines are the individual scenarios as shown in (1) [Ref. 1 is the IPCC TAR Bible, no page given]; the light blue line is the A1FI scenario, and the yellow line is the B1 scenario.
(In passing, let me again protest the use of the entire IPCC Third Annual Report, thousands of pages, as a reference without giving us chapter and verse in the way of page numbers. My high school science teacher would have slapped my hand for that, it’s a joke.)
The upper blue line is the one that gives us about a meter of sea level rise. So I took that as Rahmstorf’s 1 metre rise. To that I added, as Hansen claims we should, an amount that starts at 0.5 cm in 2000 and doubles every ten years. This is following Hansen’s claim that the non-linear ice disintegration is a separate term that starts small but will “come to dominate” the sea level rise over the century. The result is shown in Figure 4.
Figure 4. Rahmstorfs predicted rise (blue), Hansen’s projected additional rise from “non-linear ice disintegration” (dark red), and total sea level rise (green) predicted in H2011. I have included the last century’s rise of 16 cm, as calculated by Rahmstorf, in the lower right corner for comparison purposes. IMAGE SOURCE
OK, so what Hansen is actually predicting is the green line. However, his real forecast is actually much worse than that. Hansen again, emphasis mine:
The eventual sea level rise due to expected global warming under BAU GHG [greenhouse gas] scenarios is several tens of meters, as discussed at the beginning of this section.
I’m going with “several tens” to mean more than two, so he’s predicting a 30 metre sea level rise!!! … I guess he figured nobody paid any attention when Al Gore threatened us with a 20 metre sea level rise, so he’d better pull out all the stops and give us a real scare, something to make us shake in our panties.
There is a bit of good news, however. Both the Rahmstorf and the Hansen projections are already way above the reality. Since 1993, when the satellites started measuring sea level, we’ve gone up about 4.6 cm (1993-2011). Rahmstorf’s projection is 6.4 cm for that time period, about 40% too high already. Hansen’s larger projection is 7.2 centimetres rise over that time, or 55% too high.
The annual rise is also entertaining. According to the satellites, the trend 1993-2011 was 3.2 mm/yr, and has been declining recently. The change 2009-2010 was under a mm, at 0.9 mm/yr. And 2010-2011 was just about flat.
In 2010-2011, Rahmstorf’s projected rise is already 4.5 mm/yr, about fifty percent larger than the actual rate of the last 18 years. And Hansen’s annual rise is even worse, at 5.3 mm per year.
So both in terms of 1993-2011 rise, as well as current annual rise, both Rahmstorf and Hansen are already way above observations. But wait, there’s more.
Hansen’s rate of sea level rise is supposed to be accelerating, as is Rahmstorf’s rate. By 2020 Hansen says it should be rising at 6.3 mm per year, and everlastingly upwards after that. But in fact we’re already way under their supposed rates of annual increase, and the observed rate of rise is declining …
How does Hansen get these nonsensical numbers? Well, he noticed something in the observations.
This third term [melting ice] was small until the past few years, but it is has at least doubled in the past decade …
My high school science teacher, Mrs. Henniger, bless her, thought extending a linear trend into the future was a crime against nature, and I would hesitate to express her opinion on Hansen blithely extending a ~ 7% annual increase for a hundred years. That kind of compound interest turns a centimeter (3/8″) into 5 metres (16 feet). If Dr. Hansen had submitted this nonsense to her, you would not have been able to read it when it came back for the red pencil scribbles.
You can’t do that, folks. You can’t just observe that something has doubled in the last decade, and then extend that exponential growth out for a century. That’s beyond wishful thinking. That’s magical thinking.
Two final points. First, the pea under the walnut shells. Note carefully what Hansen has done. He has claimed that the sea level rise will be “several tens of metres”. This is at least thirty metres, or a hundred feet, of sea level rise.
He seems to be at least somewhat supporting this claim with his Figure 7 (my figure 2). But if you look at the caption, this is not a forecast, a projection, or a scenario of any kind. Instead, this is merely an “approximation” of what a linear sea level rise might look like and what an exponential rise might look like. You know, in case you didn’t understand “linear” and “exponential”. His actual forecast is under another walnut shell somewhere. We know his “Approximation” can’t be a real projection because it shows almost no rise occurring currently, or for some years.
Second, even this doesn’t begin to unravel the errors, deceptions, alarmism, and con games in Hansen’s work. Do you see the guy in the dark vest and the white pants and shirt at the left of Hieronymus’s painting at the top? See what he has in his hand while he’s looking all innocent at the sky? See who it’s chained to? Hansen’s not really the shell game conjurer, that guy’s a piker, he’s not making much money on the game.
Hansen’s the guy in the dark vest with his hand on your pocketbook …
w.
[UPDATE]
Joel Shore observed correctly that Hansen was basing his estimate of a huge sea level rise on paleoclimate date. Joel is right that Hansen claimed the paleoclimate data shows a rise of 20 metres for every 1°C temperature rise. Because of this, Hansen says that a 2°C future temperature rise will give a 40 metre sea level rise.
Let’s take a bit calmer look at what we know. We know that when there is an ice age, a lot of the water in the ocean behaves badly. It goes up on the land as mainly northern hemisphere ice and snow and glaciers. As a result, the sea level drops by a hundred metres or so. The glaciers stay there until the ice age ends, at which point they melt, and the sea level rises again. Since we’re in an interglacial, right now the glaciers are mostly melted.
So I would certainly not expect further warming to have much effect on melting or sea level. The easy ice is all melted, the giant miles-thick Northern Hemisphere glaciers are almost all melted back into the ocean. The rest are hiding mostly on north slopes in northern climes. So where is the meltwater going to come from?
And curiously, what I found out from Joel’s question is that if you know where to look, we can see that the graphs in Hansen’s own paper bear me out. They say the oceans won’t rise. I don’t particularly believe Hansen’s results, but presuming that they are correct for the sake of discussion, then let’s look at his graphs.
Look first at the sea level during the past four interglacial periods. I stuck a ruler on it so you can see what I mean.
As you can see, at the level of detail of their graph the sea level has never been higher than it than it is now.
Now look at their temperature observations and reconstruction:
According to Hansen, temperatures have been as much as 2.5°C higher than at present … but the sea level hasn’t ever been higher than at present.
If Hansen’s claim were true, that a 1°C temperature rise leads to a 20 m sea level rise, we should see sea levels forty metres or more above present levels in Hansen’s graph (b). Look at the scale on the left of graph (b), that’s off the top of the chart.
Instead, we see nothing of the sort. We see much warmer periods in the past, but the sea levels are indistinguishable from present levels. Hansen’s own graphs show that he is wrong. So it appears that Hansen is doing the same thing, he’s extrapolating a linear trend out well beyond the end.
He’s noticed that when warming temperatures were melting the huge glaciers over Chicago, the sea level rose quickly. Unfortunately, he has then extended that trend well past the time when there are no glaciers in Chicago left to melt …
w.
I have not looked at this but would not the starting point be to look at sea leves during the Holocene optimum and during the Minoan, the Roman and Medieval Warm Periods (although the later is all but denied as a global event).
Examination of geological data from these times would give a far better indication as to what sea levels would look like.
Just thinking of a more practical approach rather than always using models.
So, essentially, if there were a 40 meter rise in sea level, more people would live at the sea side, hence less people would drive to see the sea, ergo less emissions.
And that’s supposed to be bad. :p
A physicist says:
January 30, 2012 at 5:15 am
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Don’t forget that the North West Passage was navigated by Roald Amundsen in 1903–1906. There is a lot of evidence that it was open in the 1930s and 50s.
Melting glaciers, and I agree with Willis as to the cause, or what is left of them, drip down into the water table, replenishing it from the drought of the ice age. And there it is. Another oscillation. This one of the water table. In undeveloped valley areas, I would bet that the water table rises and falls with major epic ice ages. It rises during melt, and sinks during the ice age.
Now here is an area of human influence. The replenished water table, under the influence of wells, is sucked dry, leaving the area very vulnerable to water shortage when the table MUST fall during the drought of an ice age.
The sensationalism and shrill cries of impending doom make me and others like me suspicious of the true agenda of the screamers.
“In the space of one hundred and seventy-six years the Lower Mississippi has shortened itself two hundred and forty-two miles. Therefore … in the Old Oolitic Silurian Period the Lower Mississippi River was upward of one million three hundred thousand miles long… seven hundred and forty-two years from now the Lower Mississippi will be only a mile and three-quarters long… There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.”
Mark Twain
Richard, you are 100% right that no-one should forget Amundsen’s brave voyage in the Gjøa.
Just as no-one should forget that the Gjøa spent three winters frozen in the ice before making it through. Nowadays the Arctic ice is melting so fast (as was correctly predicted by Hansen and colleagues in 1981) that heroic voyages like the Gjøa’s will not happen again.
Uh… I thought sea levels were starting to fall,….
http://wattsupwiththat.com/2011/08/24/nasa-notes-sea-level-is-falling-in-press-release-but-calls-it-a-pothole-on-road-to-higher-seas/
And now this.
http://wattsupwiththat.com/2012/01/29/headlines-over-solar-cycle-25-and-potential-cooling/
The update by Willis says it all.
Add to this the current halt in global warming and possible future cooling and it will be all over for Hansen.
Hansen – FAIL, again.
You seriously have to wonder how these people get away with this sort of drivel. I see that one of the reviewers (Dana Royer) is named by Hansen in the acknowledgments.
I wonder if Dana has ever heard of Lavoisier, because basically Hansen has invented a new law here: H20=k.T2
Summary of Jimmy’s career . . .
First smart.
Then Sublime.
Then Ridiculous.
Now just plain ol’ Stuck on Stupid.
And to think he could have had a real legacy as a scientist and now all he will be remembered for is being the Poster Kiddie for the Great Global Warming Hysteria event.
Why does Hansen’s work always read like he has millions of Zimbabwean dollars that he has to transfer out of the country but must pay 50,000 dollars to transfer it to your account?
Any takers I have the number here?
Bill Marsh, you are 100% correct that Hansen’s 1981 predicted temperature rise for the years 1981-2011 (Hansen’s Figures 6-7), differs greatly from BEST’s observed temperature rise, for the same years 1981-2011 (BEST Figure 1).
How do they differ? The 2011 BEST global temperature rise is twice as large as Hansen’s 1981 prediction.
Ouch.
The point is that skeptics and nonskeptics alike can spin and dance and cherry-pick (and both sides do!), but neither side can change the predictions that they published back in the 1980s. And by that measure of scientific merit — which is public, open, unchangeable, and traditional — the 1981 predictions of Hansen and his nonskeptical colleagues have demonstrated outstanding scientific foresight.
Elevator Summary: Purely on the objective/public evidence, rational skepticism should regard James Hansen’s 1981 predictions as a conservative under-estimate of the likely effects of AGW.
Bill Illis says:
January 30, 2012 at 4:21 am
“If temperatures do rise about 3.0C, the Greenland glaciers will melt out but it will take 5,000 to 10,000 years.
The best example we have is the interglacial 400,000 years ago (see Willis’ chart) which was a long interglacial of over 20,000 years. This is like the current one which is expected to be the longest interglacial yet and it will be the longest interglacial yet if temperatures rise 3.0C.
In the interglacial 400,000 years ago, the southern third of Greenland melted out and small trees even grew in the southern interior. “
Temperatures in Greenland during the last interglacial was about 5 degrees centigrade warmer than at present for 10,000 years and the Greenland glaciers did not melt out.
The last sentence is an interesting example of a factoid, i. e. something that has been repeated so often that it is more or less universally accepted as a truth, though it is actually quite doubtful. It is ultimately based on a 2007 paper in Science by Willerslev et al.; “Ancient Biomolecules from Deep Ice Cores Reveal a forested South Greenland”
(available here: http://ff.org/centers/csspp/library/co2weekly/20070713/20070713_09.pdf)
In this paper four independent methods were used for dating the organic materials and they gave overlapping results in the 450-800,000 years range.
Since MIS 11, the interglacial Bill Illis is referring to occurred between 397 and 421 000 years ago, it is actually unlikely to have been the interglacial when the trees grew. Personally I would suggest MIS 13, which is known to have been a very warm and long interglacial in the northern hemisphere from paleontological and pedological data. However it shows up only weakly in the Antarctic ice-cores, so apparently it was quite cool in the southern hemisphere. Consequently it is not a Politically Correct interglacial, and is usually not mentioned in polite circles.
Given the uncertainty in dating the remains might even be from the exceptionally warm MIS 31/33 interglacial a million years ago (MIS 31/33 is within the range of three of the four dating methods, as against two for MIS 11).
Envisat sea level rise trend is at 0.789 mm/y. EOM
Unfortunately? I’m looking out my window in Lisle and I can’t wrap my head around the notion it’s unfortunate I’m not seeing a glacier!
A Physicist:
What children you must think we all are. Hansen boldly predicts that the “fabled” Northwest Passage will open and you trumpet his omniscience to intelligent adults. What’s next? Will you loudly proclaim Hansen’s genius when he predicts that the “fabled” Halley’s Comet will pass within visible distance of Earth?
I pray that you are not being paid to teach our children.
Alan Clark of Dirty Oil-berta says: A Physicist: … will you loudly proclaim Hansen’s genius when he predicts that the “fabled” Halley’s Comet will pass within visible distance of Earth?No.
But if sea-level rise does accelerate in the next two decades, then Hansen and his colleagues definitely will receive credit, for making (yet another) correct scientific prediction.
Because for nonskeptic and skeptic alike, correct long-term predictions are a public, open, unforgeable, traditional measure of scientific merit.
As measured by the predictions that Hansen and his colleagues made in 1980s, their present track record is pretty good.
That’s why rational skepticism has to conclude: “Maybe Hansen and his colleagues will be proved right yet again.”
“Maybe Hansen is right a third time.”
WOuld you please specify the first two?
Unless I’m gravely mistaken, they’ve *all* got to be wrong. I have serious doubts (as do PJB, Barski, Asmilwho and a few others, apparently).
An exponential function, on its own or in combination with a linear function, can’t continue forever. (Really, a linear would not be able to either, but let me focus on only Hansen’s current “Magical Mystery Tour.”)
The REAL curve must eventually flatten out again — perhaps abruptly — because the sea can only rise just so high; we only have just so much water on the Earth that can flow into the oceans… Perhaps a polynomial or some other function, but not certainly not a dominating exponential.
Also nice that Hansen has chosen the year 2000 as the starting point for his Figure 7 so that we mere mortals won’t possibly be confused by historical sea level rise. I imagine he did it so as to avoid being accused of splicing observational data and model projections.
A physicist says:
January 30, 2012 at 6:58 am
richard verney says: Don’t forget that the North West Passage was navigated by Roald Amundsen in 1903–1906. There is a lot of evidence that it was open in the 1930s and 50s.
Richard, you are 100% right that no-one should forget Amundsen’s brave voyage in the Gjøa.
Just as no-one should forget that the Gjøa spent three winters frozen in the ice before making it through. Nowadays the Arctic ice is melting so fast (as was correctly predicted by Hansen and colleagues in 1981) that heroic voyages like the Gjøa’s will not happen again.
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Is this a joke?
Mind you, having people like this defending Hansen is hardly helping his cause..
A physicist says:
January 30, 2012 at 7:46 am
BEST 1981 – 2011 shows 0.2°C of warming.
Hansen’s 1981 paper shows 0.4°C of warming at the low side for 1981 – 2011.
What sort of physics do you practise where ½ = 2?
Thanks for another great piece Willis! The update based on Joel’s input is priceless!
Peter Milford says:
January 30, 2012 at 4:19 am
It’s a family blog …
w.
“That’s why rational skepticism has to say “Maybe Hansen is right a third time.””
Third? He’s never been right before.
A Physicist said:
“…please let publicly acknowledge that my assertion was wrong, and that your outstanding post is 100% right-on-the-facts! ..”
A Physicist said:
“…Robert, you don’t mention where you got that information, but whoever/whatever the source was, definitely no skeptic should ever trust that source again! ”
A Physicist,
Just so I get this right…which source is it that you advise us to never trust again ? Thank you..