Guest Post by Willis Eschenbach
I came across this beautiful example of chartsmanship today in a Chris Mooney post of raw, pure, visceral alarmism, it’s a gem. It’s from the Mother Jones website and comes with the lovely headline “Humans Have Already Set in Motion 69 Feet of Sea Level Rise”. I do love the claims that something is “set in motion”, it’s scientific cowardice to make that claim, it’s totally impossible to falsify. I could claim that Vladimir Putin has “already set in motion” the next financial meltdown … could you falsify my claim? In any case, Mooney’s post shows the terribly worrying loss of ice from Greenland, from a study by Jason Box
Figure 1. Cumulative loss of ice area in Greenland. As you can see, Greenland is toast … it’s losing well over a hundred square kilometres of ice per year, and the chart shows it heading to the cellar, looks like a total meltdown coming up.
So … what actually is happening with Greenland? To figure that out, we need another chart, the real chart—the chart of the post 2000 ice loss, and what might happen over say the next century if it continues losing over a hundred cubic kilometres of ice per year.
To do that, we have to start by finding out the area of the ice sheet that covers Greenland. As usual, there are various estimates. The Physics Hypertextbook is great for this kind of thing because it gives a variety of estimates from various authors. They range from a low end of 1.7 million square kilometres to a high of 2.2 million square km. I’ll take an average of 1.9 million square km.
So … here is the effect on the Greenland ice cap that a continued loss of -131.5 km2 per year every year until 2100 would have:
Figure 2. Effect of -131.5 km2/yr ice loss on the ≈ two million square kilometres of the Greenland ice cap.
Pretty scary, huh? By the year 2100, if it continues losing ice at the rate Jason Box claims above, -131.5 km2 per year, the total ice area of Greenland will have gone from 1.90 million square km all the way down to … well, to two decimals of accuracy, by the year 2100 the ice will be down to 1.90 million square kilometres …
Gotta love those charts … in any case, let us consider the headline, “Humans Have Already Set in Motion 69 Feet of Sea Level Rise”. I suppose it is true IF we are the cause and IF the decline continues, both of which seem doubtful. Assuming all that were true, at the current rate of -131.5 km2 of ice loss per year, Greenland will be ice-free fairly soon, in only … well … 1,900,000 km2 ice area / 131.5 km2 per year annual loss ≈ 14,500 years from now …
Rats … I guess it’s a bit early to be looking for a nice piece of land for my Greenland vineyard …
w.
[UPDATE] Well, it is inevitably true that what I think is clear actually isn’t … no surprise there. From the comments:
Kasuha says:
February 7, 2013 at 8:28 am
Um, you know… “Greenland marine-terminating glacier area changes” and “cumulative loss of ice area in Greenland” are two a bit different things. Or rather, very different things.
Maybe you should take one more look at what exactly are you doing here.
I completely agree with the conclusion that the alarmism is unsubstantiated in this case. But the way you used to get there is not valid.
I agree with you, Kasuha, that “Greenland marine-terminating glacier area changes” and “cumulative loss of ice area in Greenland” are two very different things. That’s the problem. Mooney is using a chart of the changes in the area of the discharge of the Greenland ice into the ocean as the screaming visual for a claim that we’ve set in motion a 69 foot sea level rise … and the two have absolutely nothing to do with each other.
I didn’t know how to best discuss that kind of lunacy, so I took the path of saying well, suppose Boxes’ results were correct and it actually made a difference regarding the ice area, what difference would it make? I was not attempting to model the entire ice loss of Greenland, as I’ve been through that question in some detail already …
Perhaps there are better ways to get the point across, as you point out … that’s the one I picked.
Thanks,
w.
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>In 1942 a USAF P-38 crash landed on the Greeland Ice Sheet.
They dug her up 50 years later under 268 feet of ice.
So much for Greenlands ice melt.
To look it up, just type in “Glacier Girl” on your search engine.
————————-
Not only that. In the 1990’s they left some equipment on the ice and came back a few yrs later and had to dig down through 20 ft of new ice to retrieve it.
Mooney, Lewandowsky, Gleick, and the other quakademics are best represented by this worthy AGW spokesman:
Shades of the “low-information voter”.
Mark H.
Am I mistaken or is he confusing surface area with volume?
This reminded me of Mark Twain’s observations on the Mississippi delta:
In the space of one hundred and seventy-six years the Lower Mississippi has shortened itself two hundred and forty-two miles. That is an average of a trifle over one mile and a third per year. Therefore, any calm person, who is not blind or idiotic, can see that in the Old Oolitic Silurian Period, just a million years ago next November, the Lower Mississippi River was upwards of one million three hundred thousand miles long, and stuck out over the Gulf of Mexico like a fishing-rod. And by the same token any person can see that seven hundred and forty-two years from now the Lower Mississippi will be only a mile and three-quarters long, and Cairo and New Orleans will have joined their streets together, and be plodding comfortably along under a single mayor and a mutual board of aldermen. There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.
– Life on the Mississippi
Thanks for starting my day with a smile, Willis.
Willis posted:
> Rats … I guess it’s a bit early to be looking for a nice piece of land for my Greenland vineyard
Oh no, go right ahead. you ought to be able to get a a great deal on some newly exposed land today, and then you can add some 100km^2 each year for 14,000 years. Dare to be Great! And if it gets cold again, switch to Ice Wine. 🙂
Peter Laux says:
February 7, 2013 at 7:02 am
—
If you believe that the fact that “Glacier Girl” was found under 268 feet of ice means that the glaciers are 268 feet higher than they were 50 years ago, then you need to study up on how glaciers work. To grossly simplify it, snow falls at the top of the glacier. As more snow falls, it the weight compresses it to ice. As more snow falls, the weight forces the ice to start flowing downhill. Every bit of ice at the bottom of the glacier was, at one point in time, higher up in the glacier, some of it at the top.
Hasn’t the rise in sea levels been slowing recently?
Um, you know… “Greenland marine-terminating glacier area changes” and “cumulative loss of ice area in Greenland” are two a bit different things. Or rather, very different things.
Maybe you should take one more look at what exactly are you doing here.
I completely agree with the conclusion that the alarmism is unsubstantiated in this case. But the way you used to get there is not valid.
Thanks, Willis.
It seems like Greenland is not going green!
Anytime you see “X cubic kilometers of ice melting” and allusions to sea level rise, please keep the following in mind…
Conversion factors for ice and water mass and volume:
http://climatesanity.wordpress.com/conversion-factors-for-ice-and-water-mass-and-volume/
For example: 1 cubic kilometer of water added to the oceans raises them by about 2.8 microns.
Good article. BTW, may I quote you on the “Putin has already set in motion the next financial meltdown”.
I think I see an opportunity here.
@wte9 “Isn’t the real question how much ice loss will cause sixty-nine feet of sea level rise?”
According to wikipedia if the *entire* Greenland ice sheet melted the rise would be ~24 feet. [http://en.wikipedia.org/wiki/Greenland_ice_sheet].
Mike.
The idea that humans are cause of everything (especially perceived “bad things”) is so egotistical.
The chart from Box is actually marine terminating glacial area.
So, it looks as though Box is calculating the change in area of those glaciers that terminate in the water. You know, places where ice melts and adds to sea level.
Willis, is looking at the total area. So you have a classic apples and tire irons comparison.
So, one guy is looking at the periphery of the ice and noting the loss of ice area. That relates to rising sea levels. Smaller area than the whole of Greenland. And the other guy is looking at the total area of greenland. Apples and Tire irons.
I suppose one should go back to Box’s article and actually check his data and methods before saying much more. On the surface it looks like folks are talking about two different things
“Figure 1. Cumulative loss of ice area in Greenland.”
That figure says it’s the area change of the marine terminating glaciers. So for your chart to make any sense you’d either need to find a source of the actual cumulative loss of ice area in Greenland or only consider the area of the marine terminating glaciers.
(Source: IPCC 2001 WG1, via Wikipedia)
The total area of Greenland is 2,166,086 km2 (836,330 sq mi) (including other offshore minor islands), of which the Greenland ice sheet covers [in area] 1,755,637 km2 (677,855 sq mi) (81%) and has a volume of approximately 2,850,000 km3 (680,000 cu mi). [38 IPCC]
2000km3 of melted ice (2000-2012) into 3,6*10e8km2 ocean gives 0,005mm(!) sealevel rise (0,0002inch) or 0,0004mm/year or 0,04mm/century.
Now, I’m worried (NOT 🙂
Evolving Mooney
2007 :The broad point Yoffe is trying to make is that we shouldn’t be “terrified” all the time about global warming — and that those who are trying to terrify us (Gore, allegedly) are probably shooting themselves in the foot.
As a general statement, there’s some truth to this. I myself have been making this argument, along with a colleague, in a public talk on science communication that (among other things) tries to dissuade environmentalists from framing global warming as a “Pandora’s box” all the time.
http://www.huffingtonpost.com/chris-mooney/if-attacking-al-gore-was-_b_53747.html
I guess the Vikings better cancel the caterer for their resettlement party, alas!
Just a chartmanship technicality .. in Figure 2, the vertical axis should be in units of km2, not km3.
“Greenland will be ice-free fairly soon, in only … well … 1,900,000 km2 ice area / 131.5 km2 per year annual loss ≈14,500 years from now”
Assuming we’re not well into a Grim Global Glaciation (GGG) by then.
You’re right that the current rate ice melt is low, but Mooney’s graph certainly shows a strong trend. One would expect that the rate of melt will increase as the temperature increases. So, the idea that a linear rate of ice loss can be extrapolated ove many decades seems highly unlikely. What will happen if the warming continues?
Crispin and John above. The really surprising conclusion that we can draw from your comment is that scientists, especially those who publish their results in peer-reviewed journals, seem to be exceptionally innumerate.
For my part, I will expect that blog posts will often be misleading, whether for or against climate change, while journal articles will provide the best visual and verbal presentation of data.
Just for “fun”, what would the graph look like is one “assumed” a doubling of the ice loss every 10 years?