I wonder if Greenland feels like Goldilochs?

Posted: May 24, 2010 in My BS (Bad Science) detector, Science


This was a topic on http://wattsupwiththat.com/2010/05/23/on-being-the-wrong-size/ guest post by Willis Eschenbach
This topic is a particular peeve of mine, so I hope I will be forgiven if I wax wroth.

There is a most marvelous piece of technology called the GRACE satellites, which stands for the Gravity Recovery and Climate Experiment. It is composed of two satellites flying in formation. Measuring the distance between the two satellites to the nearest micron (a hundredth of the width of a hair) allows us to calculate the weight of things on the earth very accurately.

One of the things that the GRACE satellites have allowed us to calculate is the ice loss from the Greenland Ice Cap. There is a new article about the Greenland results called Weighing Greenland.

Figure 1. The two GRACE satellites flying in tandem, and constantly measuring the distance between them.

So, what’s not to like about the article?

Well, the article opens by saying:

Scott Luthcke weighs Greenland — every 10 days. And the island has been losing weight, an average of 183 gigatons (or 200 cubic kilometers) — in ice — annually during the past six years. That’s one third the volume of water in Lake Erie every year. Greenland’s shrinking ice sheet offers some of the most powerful evidence of global warming.

Now, that sounds pretty scary, it’s losing a third of the volume of Lake Erie every year. Can’t have that.

But what does that volume, a third of Lake Erie, really mean? We could also say that it’s 80 million Olympic swimming pools, or 400 times the volume of Sydney Harbor, or about the same volume as the known world oil reserves. Or we could say the ice loss is 550 times the weight of all humans on the Earth, or the weight of 31,000 Great Pyramids … but we’re getting no closer to understanding what that ice loss means.

To understand what it means, there is only one thing to which we should compare the ice loss, and that is the ice volume of the Greenland Ice Cap itself. So how many cubic kilometres of ice are sitting up there on Greenland?

My favorite reference for these kinds of questions is the Physics Factbook, because rather than give just one number, they give a variety of answers from different authors. In this case I went to the page on Polar Ice Caps. It gives the following answers:

Spaulding & Markowitz, Heath Earth Science. Heath, 1994: 195. says less than 5.1 million cubic kilometres (often written as “km^3″).

“Greenland.” World Book Encyclopedia. Chicago: World Book, 1999: 325 says 2.8 million km^3.

Satellite Image Atlas of Glaciers of the World. US Geological Survey (USGS) says 2.6 million km^3.

Schultz, Gwen. Ice Age Lost. 1974. 232, 75. also says 2.6 million km^3.

Denmark/Greenland. Greenland Tourism. Danish Tourist Board says less than 5.5 million km^3.

Which of these should we choose? Well, the two larger figures both say “less than”, so they are upper limits. The Physics Factbook says “From my research, I have found different values for the volume of the polar ice caps. … For Greenland, it is approximately 3,000,000 km^3.” Of course, we would have to say that there is an error in that figure, likely on the order of ± 0.4 million km^3 or so.

So now we have something to which we can compare our one-third of Lake Erie or 400 Sidney Harbors or 550 times the weight of the global population. And when we do so, we find that the annual loss is around 200 km^3 lost annually out of some 3,000,000 km^3 total. This means that Greenland is losing about 0.007% of its total mass every year … seven thousandths of one percent lost annually, be still, my beating heart …

And if that terrifying rate of loss continues unabated, of course, it will all be gone in a mere 15,000 years.

That’s my pet peeve, that numbers are being presented in the most frightening way possible. The loss of 200 km^3 of ice per year is not “some of the most powerful evidence of global warming”, that’s hyperbole. It is a trivial change in a huge block of ice.

And what about the errors in the measurements? We know that the error in the Greenland Ice Cap is on the order of 0.4 million km^3. How about the error in the GRACE measurements? This reference indicates that there is about a ± 10% error in the GRACE Greenland estimates. How does that affect our numbers?

Well, if we take the small estimate of ice cap volume, and the large estimate of loss, we get 220 km^3 lost annually / 2,600,000 km^3 total. This is an annual loss of 0.008%, and a time to total loss of 12,000 years.

Going the other way, we get 180 km^3 lost annually / 3,400,000 km^3 total. This is an annual loss of 0.005%, and a time to total loss of 19,000 years.

It is always important to include the errors in the calculation, to see if they make a significant difference in the result. In this case they happen to not make much difference, but each case is different.

That’s what angrifies my blood mightily, meaningless numbers with no errors presented for maximum shock value. Looking at the real measure, we find that Greenland is losing around 0.005% — 0.008% of its ice annually, and if that rate continues, since this is May 23rd, 2010, the Greenland Ice Cap will disappear entirely somewhere between the year 14010 and the year 21010 … on May 23rd …

So the next time you read something that breathlessly says …

“If this activity in northwest Greenland continues and really accelerates some of the major glaciers in the area — like the Humboldt Glacier and the Peterman Glacier — Greenland’s total ice loss could easily be increased by an additional 50 to 100 cubic kilometers (12 to 24 cubic miles) within a few years”

… you can say “Well, if it does increase by the larger estimate of 100 cubic km per year, and that’s a big if since the scientists are just guessing, that would increase the loss from 0.007% per year to around 0.010% per year, meaning that the Greenland Ice Cap would only last until May 23rd, 12010.”

Finally, the original article that got my blood boiling finishes as follows:

The good news for Luthcke is that a separate team using an entirely different method has come up with measurements of Greenland’s melting ice that, he says, are almost identical to his GRACE data. The bad news, of course, is that both sets of measurements make it all the more certain that Greenland’s ice is melting faster than anyone expected.

Oh, please, spare me. As the article points out, we’ve only been measuring Greenland ice using the GRACE satellites for six years now. How could anyone have “expected” anything? What, were they expecting a loss of 0.003% or something? And how is a Greenland ice loss of seven thousandths of one percent per year “bad news”? Grrrr …

I’ll stop here, as I can feel my blood pressure rising again. And as this is a family blog, I don’t want to revert to being the un-reformed cowboy I was in my youth, because if I did I’d start needlessly but imaginatively and loudly speculating on the ancestry, personal habits, and sexual malpractices of the author of said article … instead, I’m going to go drink a Corona beer and reflect on the strange vagaries of human beings, who always seem to want to read “bad news”.

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Comments
  1. sonsothunder says:

    That’s a pretty good analogy, or wait, was Goldilocks over weight? Anyway, yeah, I can related to what you are saying, that much of the general public seem to rush to the scene of an accident, to gawk upon it to see what they can see, before, they reach for the cell phone and call 911. Then there are the rubber-necker’s who run into the back of you while they were turned to see the accident, instead of watching where they were going.

    Yeah, I see what you mean. But, on a more serious note, which, I am sure is where you were writing from, this obviously, in my opinion anyway, the fact base releases, from the Gore camp…Which, I don’t really know enough of the mechanics of to get involved in a conversation about, other than to say that:

    Seems only when it fattens the pocketbooks of the constituents of certain agendas, do the “Heightening Public Awareness” committees result to “Using Alarmist Tactics” and propaganda of crucially, or potentially threatening terms.
    If any of that makes sense…
    Anyway, great post, and I wish I were more up to date on some of the issues that you raise here, to even communicate with you on….But, if you build it…they will come..if for nothing else…on of those Coronas/w Lime

    • well come back around and make comments and ask questions, that’s what this blog is for.
      And you know more than you think you do.
      That is exactly what this is all about.
      Get people all stirred up, play Chicken Little, and while they’re all worried about the world burning up, slap a cap and trade carbon tax on ’em and tax their bahookies back to the dark ages.
      Google the riots in Greece and cap and trade policies in Spain (Their wonderful bankrupt country and they’re 20% National Unemployment rate which is going higher and higher each month) and that is exactly where Obama and Gore and Soros and others get rich. Google the Chicago Carbon Exchange, Al Gores two businesses that control carbon credit trading and how Gore, Obama and George Soros want to promote cap and trade…. Can you say conspiracy? Can you say oh no you don’t get my wallet and spread my hard earned cash around third world countries and line your fat coffers.

      Does anyone ask where Gore gets his money from? He hasn’t been in politics for 8 years. He doesn’t have a job like you or I do. Yet he just bought another mansion in Southern California, right on the coast. Ask yourself …. “hmm why if Al Gore is concerned about Global Warming, is he buying a house for 3+ Million dollars on the beach in California? Why if he cares so much about ecology and saving energy did he spend over 30k 2 years in a row in electrical bills and expend 250,000kw of energy. Enough energy to power 2500 homes for a month.

      Things that make ya go hmmmmmmmmmmmmmmmmm.

  2. sonsothunder says:

    Shoot!! All I know, is his entourage left the more than a dozen Escapade, (Cadillac) SUV’s running so that the Air-conditioning was still primed, when he exited the (Global Warming Pro-Liberal Speeches ) promoting the Global Warming, conserve energy!!! speeches last summer…as he made his quick smiling get away…to his Personal get (my ass home to luxury) Lear jet… thanks for commenting on the ( He just walked away)…pass the salt please….

  3. sonsothunder says:

    hehe, Yeah, and look at that guy…if he’s on a Tofu Diet…I’m a …
    Okay, I guess I shouldn’t resort to cheap personal attacks…But, he does sort of leave the door wide open for them. I mean, he’s definitely not a genuine article. Just my opinion.

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