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”.
DirkH says:
May 23, 2010 at 10:04 am
“Paul Daniel Ash says:
[…]
And in “twenty years or so,” if the majority of the world’s scientists are drawing the correct conclusion from the data, we will be in that much worse of a pickle.”
Science is not about majorities, Paul. It’s about evidence. I think you’re confusing it with politics.
_________________________________________________________________________
No he just made a freudian slip, thats all because CAGW is all about politics not science.
Robert
“This factor is taken into account, see Khan et al. 2010, for example. There are many locations which have Differential GPS on the bedrock of the GIS (Greenland Ice Sheet) which help scientists measure this. So before you speak, get your facts straight if you’re not an expert in the field. Secondly the volume of the ice cap is also measured using radar interferometry, climate modelling, radar altimetry and laser altimetry so we do have a decent clue.”
GPS on the bedrock – beneath 2-3kms of ice?
Radar interferometry cannot accurately penetrate more than 100 metres of ice.
Radar altimetry can measure the surface of the ice, but not what the bedrock is doing.
Climate modelling – the voodoo or the astrological type?
Why are you alarmists always so impolite?
Hi janama, thanks for this interesting link, now who would ever think it just might be magma and possibly even a volcano underneath Greenland? (a proper scientist)
Heat From Earth’s Magma Contributing To Melting Of Greenland Ice
Hot magma, loss of density, therefore loss of gravitational field implies mass loss, let alone the actual loss of mass from the deep melting underneath the ice sheet as this article indicates. Whether GRACE team is actually considering or correcting for this seems unknown at this point.
http://www.washingtonpost.com/wp-dyn/content/article/2010/05/12/AR2010051202190.html
“BP agreed in 2004 to the installation of a test valve and replacement of another key part on the Deepwater Horizon’s blowout preventer, even though it acknowledged that doing so would reduce redundancies and increase risks on the drilling rig.”
“A House energy panel investigation has found that the blowout preventer that failed to stop a huge oil spill in the Gulf of Mexico had a dead battery in its control pod, leaks in its hydraulic system, a “useless” test version of a key component and a cutting tool that wasn’t strong enough to shear through steel joints in the well pipe and stop the flow of oil.”
Ahem, ahem, ahem. Exodus 22:24 reads as follows:-
“And my wrath shall wax hot, and I will kill you with the sword; and your wives shall be widows, and your children fatherless.”
One’s ‘wrath’ waxes hot, not ‘wroth’.
Picky, I know, but let’s get things right!
Otherwise … Spot on, Willis!!
I’m all for extrapolating measurements 12,000 or 19,000 years into the future, whatever it takes. But that’s not necessary here.
According to this Science paper:
http://www.sciencemag.org/cgi/content/short/326/5955/984
the total Greenland ice mass loss for 2000 to 2008 was 1500 Gt (166.66 Gt/yr).
Yet the loss rate in the final three years, 2006 to 2008, was 273 Gt/yr.
Hence, in 9 years, the ice mass loss accelerated by 273/166.66 = 1.638 times
Extrapolating this acceleration, we see every 9 years the mass loss will increase by a factor of 1.638.
In just 18 periods of 9 year accelerations, the rate of mass loss will be:
1.638^18 = 7,205.27 * 166.66 Gt/yr = 1,200,830 Gt/yr
18 * 9 = 162 years from the beginning year, 2000.
Since Greenland has only 2,850,000 cubic kilometers of ice, clearly it will all be gone way before 153 years from now – the three year average melting rate of 1,200,830 Gt/yr would melt it all in less than 3 years, plus you must integrate all the melt from the previous years to get the actual date of ice-free Greenland.
Certainly before 2162.
Great news for Denmark – long live the Queen.
David, a bit more research, and Transocean claims BP paid for the changes to the BOP as it reduced the time to start the well. See testimony before Congress. More on the actual issue from Wikipedia, well sourced, go there:
“Attention has focused on the cementing procedure and the Cameron TL blowout preventer, which failed to engage.[34] A number of significant problems have been identified with the blowout preventer: There was a leak in the hydraulic system that provides power to the shear rams. The underwater control panel had been disconnected from the bore ram, and instead connected to a test hydraulic ram. The blowout preventer schematic drawings, provided by Transocean to BP, do not correspond to the structure that is on the ocean bottom. The blowout preventer shear ram would not have been powerful enough to cut through joints in the well pipe as it is only effective on the body of a drill pipe. The explosion may have severed the communication link so the blowout preventer would have never received the instruction to engage. Before the backup dead man’s switch could engage, communications, power and hydraulic lines must all be severed, and its possible hydraulic lines were intact after the explosion. Of the two control pods for the deadman switch, the one that has been inspected so far had a dead battery.[48]
In other testimony, the Minerals Management Service officials said there have been 39 fires or explosions offshore in the Gulf of Mexico in the first five months of 2009, the last period with statistics available.[30][41] There had been numerous previous spills and fires on the Deepwater Horizon, which had been issued citations for “acknowledged pollution source” by the Coast Guard 18 times between 2000 and 2010. The previous fires were not considered unusual for a Gulf platform and have not been connected to the April 2010 explosion and spill.[35] The Deepwater Horizon did, however, have other serious incidents including a 2008 incident where 77 persons were evacuated from the platform after it listed over and began to sink after a section of pipe was accidentally removed from the platform’s ballast system.[49] According to a report by 60 Minutes, the blowout preventer was damaged in a previously unreported accident four weeks before the April 20 explosion, and BP overruled the drilling operator on key operations. BP declined to comment on the report.[50]”
morgo says:
May 23, 2010 at 10:40 am
all the 5 year old kids know that the arctic is melting and all the polar bears are going to drown there teachers told them, it must be true . HOW DO WE GET THE RIGHT MESSAGE THROUGH TO THEM ?
___________________________________________________________________________
You have three options.
1. Remove your kid from the school and home school or private school.
2. Get together with some friends, storm the school and complain LOUDLY.
1. Get together with a couple of other friends who have kids that have had their children frightened by this PROPAGANDA, hire a lawyer and sue the britches off the school system and teacher.
The last one is unfortunately your best bet. No matter what the state of the science, NO Teacher has the RIGHT to frighten children into having nightmares. That is child abuse.
For your kid show them the video from The Minnesota Majority
The original may still be here: http://wattsupwiththat.com/2010/04/21/second-mann-spoof-video-removed/#comment-374324
Other wise the second version is here:
I don’t know if this has been noted yet, but the article cited by Willis originally appeared on the Union of Concerned Scientists (UCS) web site. See: http://www.ucsusa.org/global_warming/science_and_impacts/science/climate-scientist-scott-luthcke.html.
John Stossel calls the UCS web site a left wing “smear site” (see http://www.jewishworldreview.com/0405/stossel041305.php3.) A more detailed expose of the UCS titled “The Union of Concerned Scientists: It’s Jihad against Climate Skeptics” appears here: http://www.capitalresearch.org/pubs/pdf/v1186063502.pdf. If you use the WUWT search engine, you’ll find other articles about the UCS.
Stephen Brown,
I know we talk funny over here, but my handy desktop dictionary says wroth is Old English for wrath; of German origin.
Anu says:
May 23, 2010 at 1:57 pm
I’m all for extrapolating measurements 12,000 or 19,000 years into the future, whatever it takes. But that’s not necessary here.
According to this Science paper:
http://www.sciencemag.org/cgi/content/short/326/5955/984
the total Greenland ice mass loss for 2000 to 2008 was 1500 Gt (166.66 Gt/yr).
Yet the loss rate in the final three years, 2006 to 2008, was 273 Gt/yr.
Hence, in 9 years, the ice mass loss accelerated by 273/166.66 = 1.638 times
Extrapolating this acceleration, we see every 9 years the mass loss will increase by a factor of 1.638.
The maps at the Drought Monitor site indicate that large parts of Greenland have been under severe to exceptional drought conditions for the best part of the last three years
http://drought.mssl.ucl.ac.uk/drought.html?map=%2Fwww%2Fdrought%2Fweb_pages%2Fdrought.map&program=%2Fcgi-bin%2Fmapserv&root=%2Fwww%2Fdrought2%2F&map_web_imagepath=%2Ftmp%2F&map_web_imageurl=%2Ftmp%2F&map_web_template=%2Fdrought.html
This would seem to indicate that lack of replenishment is a more likely culprit for the decline in mass balance, than enhanced melting. It seems a little unreasonable to project those drought conditions to persist and worsen for 150 years.
mike Abbott says:
May 23, 2010 at 2:18 pm
Climate skeptics are much more at home at the Union of Unconcerned Scientists:
http://unconcernedscientists.org/
http://theeasternreview.com/issues/3/news/uus.shtml
Check it out.
Or not.
Whatever.
Paul Daniel Ash says:
May 23, 2010 at 6:59 am
And if that terrifying rate of loss continues unabated, of course, it will all be gone in a mere 15,000 years.
Is anyone talking about the loss of the Greenland Ice Cap? No, no they are not. So this is a ridiculous straw man.
Go and scrutinize the Kerry Emmanuel video interview segment with the Boston Globe from a week ago
http://www.boston.com/lifestyle/green/articles/2010/05/16/global_warming_debate_makes_climate_tough_on_friends/
Pay special attention at the 1;30-2:00 runtime. It certainly seems to me that KE is raising the spector of Greenland melting and creating 22 feet of sea level rise. I think he views himself as very much a member of the “consensus climate community”
Glaciers pick up rocks, don’t they?
And then drop them into the sea?
Has anybody done a calculation of how much rock is lost in calved glaciers from Greenland every year?
Re the isostatic impact of changes in ice mass and ice distribution.
Upwards and downwards movement of the rock surface below the ice are not the only issue. Changes in ice loading force lateral movement within the semi-plastic rock that makes up the underlying mantle. This is what causes the development of widespread down-warping under icesheets, the surface bulging that surrounds major ice sheets, and the collapse of these isostatic bulges when an ice sheet melts.
So if there is isostatic rebound under Greenland part of this is due to a continuation of the horizontal movement of “soft” rock in the mantle. These movements can continue for 10’s of thousands of years after the main reduction or increase in ice mass. In the case of Greenland current isostatic rebound is accompanied by an inflow of rock mass at a depth of hundreds of km below the surface.
So clearly if there is long-term, ongoing, non-anthropogenic isostatic recovery from the last ice age then the mass of mantle rock beneath greenland must be increasing. How do they calculte this and separate it from changes in modern ice mass (last 10 to 20 yrs worth)? That can’t be easy and it is another potential source of error, as the rate of movement in the mantle will not be easy to measure directly. The best that can be done is to model it.
Willis Eschenbach:
“Jeff L, you and tty are right about isostatic rebound, and I was wrong. The mass of the Greenland bedrock is not changing. ”
Wrong again. What is actually happening with isostatic readjustment is that material is slowly flowing from areas that are sinking to areas that are rising, so yes, the mass of bedrock IS changing.
Anu, how do I join the UUS? I need an application form, which I may or may not get around to completing if I should decide to become a member.☺
You’re right, scientific skeptics such as I would be much more at home there, than would be the frightened believers in looming climate catastrophe — who no doubt scream like terrified schoolgirls upon seeing a spider — whenever they read the next breathless account of rising sea levels or declining Arctic ice.
tty says:
May 23, 2010 at 3:32 pm
I thought the magma was what was flowing, not the bedrock.
I’m probably not the first, but anyway:
What’s that in elephants?
Well I think it is interesting that they do have to try to model and adjust for non-gravitational acceleration, because it is losing altitude over the years.
I am confused as to the “percent” rate of ice loss. Maybe I am misreading something, or someone can correct me on this. The amount ice lost is given as 200 km^3 per year which I assume is taken to be constant. The total amount of ice is about 3,000,000 km^3. The period stated to get rid of all the ice is 15,000 years which is fine. However, the percent rate seems to be stated as a constant .007% per year. This only works for the first year. The percent rate will increase exponentially as the volume of ice decreases while the loss rate remains constant. Am I missing something?
@ur momisugly Willis Eschenbach:
“So I would say that their error estimates are no more out of line than the rest of the basic scientists in the field … which is either damning with a faint praise, or praising with a faint damn …”
I prefer the original continuation of Pope line:
Damn with faint praise, assent with civil leer,
[And, without sneering, teach the rest to sneer.]
Brad says:
May 23, 2010 at 1:58 pm
BP did not in fact do the modification, only paid to have it done. If done incorrectly, would that be the responsibility of the contrcator or the contractee?
“This topic is a particular peeve of mine, so I hope I will be forgiven if I wax wroth.”
You’re not supposed to get emotional over ‘global warming’. That Canadian guy says to walk it off when you feel emotions. 😉
tty says:
May 23, 2010 at 3:32 pm
“What is actually happening with isostatic readjustment is that material is slowly flowing from areas that are sinking to areas that are rising, so yes, the mass of bedrock IS changing.”
======================
I assume this is a theory?, considering the specific gravity of the magma underlying the crust is in flux.