By Steven Goddard,
The headline reads “NASA Satellites Detect Unexpected Ice Loss in East Antarctica”
ScienceDaily (Nov. 26, 2009) — Using gravity measurement data from the NASA/German Aerospace Center’s Gravity Recovery and Climate Experiment (GRACE) mission, a team of scientists from the University of Texas at Austin has found that the East Antarctic ice sheet-home to about 90 percent of Earth’s solid fresh water and previously considered stable-may have begun to lose ice.
Better move to higher ground! NASA also reported :
In 2007, NASA generated this map (below) of Antarctica showing just how hot it is getting down there in the land of Penguins.
Now I am really worried! But wait……. There are a few minor problems.
Assume for a minute that we accept the GRACE numbers. The first problem is Antarctica contains a lot of ice : 30 × 10^6 km³. At 100 km³ per year, it will take 300,000 years to melt.
The next problem is with the NASA temperature map. From the NASA article “The scientists estimate the level of uncertainty in the measurements is between 2-3 degrees Celsius.” They are claiming precision of better than 0.05°C, with an error more than an order of magnitude larger than their 25 year trend. The error bar is large enough that the same data could just as easily indicate rapid cooling and blue colors. That will get you an F in any high school science class.
And that is exactly what happened. The hot red map above was preceded by a cold blue map which showed Antarctica getting cooler. What motivation could NASA have had to change colors without mathematical justification?
NASA justified their heating up Antarctica with this comment :
This image was first published on April 27, 2006, and it was based on data from 1981-2004. A more recent version was published on November 21, 2007. The new version extended the data range through 2007, and was based on a revised analysis that included better inter-calibration among all the satellite records that are part of the time series.
As I have already pointed out, this is absurd. Their error bar is so large that they could have painted the map any color they wanted. Apparently someone at NASA wanted red.
But why are we looking at temperature trends anyway? The real issue is absolute temperatures. Some of the regions in which GRACE claims ice loss in East Antarctica average colder than -30°C during the summer, and never, ever get above freezing. How can you melt ice at those temperatures?
http://en.wikipedia.org/wiki/File:Antarctic_surface_temperature.png
I overlaid the Antarctica summer temperature map on the GRACE “melt” map, below. As you can see, GRACE is showing ice loss in places that stay incredibly cold, all year round.
The problem with GRACE is that it measures gravity, not ice. Changes in gravity can be due to a lot of different things beneath the surface of the ice. Antarctica has active magma chambers. Plate tectonics and isostasy also cause gravity changes.
We should be clever enough not to be blinded by technology. The claims that ice is melting in East Antarctica don’t have a lot of justification.
I don’t know if things are different in Antarctica, but alpine and tidewater glaciers in Canada and Alaska do not consist exclusively of ice. Terminal moraines don’t melt and they isolate a glacier’s snout from the erosive action of the sea. They also constitute a significant resistance to the downward slide of the mass of ice behind them. Much more, I would have thought, than any amount of floating ice.
It is normal for many deep crevasses to open up perpendicular to the direction of glacier movement. Maybe all the fluid dynamics comparisons have their counterpart to that phenomenon. A sort of cavitating venturi, perhaps?
If people simply read the paper they would find
then they would not have to ask questions regarding the spatial leakage of the GRACE signal into neighbouring land and ocean areas.
Steven Goddard, you have stirred up several hornet nests recently, congratulations. I particularly liked: EFS_Junior’s comment:
“For the record WUWT is NOT a SCIENCE blog.
And that’s a FACT!”
Funny, because everyone keeps coming back here to argue the science… It could take years of traditional research to figure out what WUWT can figure out in one thread. It’s like peer review on steroids…
Chris Noble says:
July 1, 2010 at 10:36 pm
If people simply read the paper they would find
” The spatial resolution of GRACE is limited by its ∼460 km altitude, to no better than a few hundred kilometres10,13,14 . This exceeds the scale of most glacial drainage basins”
Let me repeat slowly:
A lot of us are retired scientists. I am a retired particle physicist.
A lot of us do not live near the libraries. I am 100 km away from one, even though within the error of GRACE.
It is courteous to find copies of what you are explaining in a reference that is not behind a pay wall.
Your quote there made me laugh: 300 kilometer spatial resolution giving mm changes in values is really something.
I guess if I payed to look at the articles I would be enlightened, but I doubt it. I recently ( living in Greece) got a 30% cut on my pension, so even if it were Einstein’s relativity paper, I would not pay to have a copy.
Just that facts: WUWT as scienceblog sees how facts are presented in the news. It’s presented like the ice sheets melt at the surface, whereas it’s the grounding line of ice shelves under the sea that retreats further inland triggering ice flows ( link curtesy Chris Noble. This is consistent with an increase in ocean heat content down there, while ocean surface cools and puts a bigger ice lid. That’s a fact. The question that Grace does not answer is what causes OHCchange down there or at the bedrock, while surface temperature cools. Global warming? Volcanos? Don’t you need to put “Global warming” on each paper to get more research grants? Nobody is intrested to investigate about undersea volcanos lest he may appear on a blacklist.
Chris Noble says:
July 1, 2010 at 10:27 pm
It appears that you are acknowledging that the authors are confusing isostasy with ice loss. Isn’t that what this article is about?
Read the paper and supplementary material.
http://www.nature.com/ngeo/journal/v2/n12/abs/ngeo694.html
They discuss at length the sources and likely magnitudes of errors in the calculations.
Is it really too much to ask for you to read the paper and address points made in the paper rather than a series of straw men?
Just a suggestion. If you want to rant about people not reading your references you might want to limit yourself to papers which are not paywalled. From previous experience I’ve had with ponying up to view some brilliant piece of wisdom at Nature, I am no longer personally inclined to repeat the experiment.
Chris, thanks for your response to my question.
Chris Noble says:
July 1, 2010 at 10:36 pm
If the article weren’t behind a paywall, I’d do just that, read the paper … in any case, you point out that the article says the spatial resolution is a “few hundred kilometres” … that’s not very informative at all. 300 km? 600 km? If these folks know the spatial resolution, why don’t they say what it is?
You also point out that they are using a 300 km gaussian filter. I always get very suspicious when I see that. When you are looking (as I assume they are) for good resolution and fine detail, the only reason I can see to use a gaussian filter is to hide the variations in the signal … I’d love to see the results without the filter, so we can see how accurate and precise GRACE actually is, and how much of what we are seeing are smoothed artifacts.
GRACE seems like a very blunt tool the way that they are using it. For some things that would be fine. I’m not sure it is adequate for this task.
Chris Noble says:
July 1, 2010 at 9:46 pm (Edit)
How would my reading the paper settle a difference of opinion between you and Phil? In any case, send me a copy, I’ll be glad to read it.
Just the facts,
Because outsiders bring science here, it doesn’t make this a science blog, per se.
kadaka (KD Knoebel) says:
July 1, 2010 at 2:17 pm
PS: Re: Paul Birch on July 1, 2010 at 12:03 pm
I saw your comment after writing and when I checked the comments before posting. Well, Wikipedia thinks it could be related, so you can take that up with them. 😉
______________________________________________________________________
Look at the phase diagram on that wiki page. You’ll see that for pressures in the 10MN/m2 range (equivalent to km depths) the melting point only shifts a few degrees below zero. By itself pressure could not melt the base of the ice. The Earth’s heat does that, and, once the ice starts to move, frictional heat from its motion. The frictional melting can be considerable: per km depth of ice, and assuming an effective coefficient of friction of only 1% (which is pretty low) and a velocity of 10m/yr, we have 1MJ/m2/yr, which will melt 5mm/yr. Localised melting around obstacles can easily be more than ten thousand times higher (~10m/yr or more), quite sufficient to maintain the flow.
Doug McGee says:
“Because outsiders bring science here, it doesn’t make this a science blog, per se.”
Maybe not, but WUWT is certainly the most popular choice among interested readers, having won the “Best Science” category in the latest Weblog Awards, and the #1 Science spot in the Wikio awards.
The people who visit WUWT know more and better science than the average blog reader, and that includes readers of blogs like RealClimate, climate progress, tamino, and the rest of the alarmist echo chambers — which cater primarily to the relative handful of true believers in the debunked CO2=CAGW agenda.
And unlike those one-sided propaganda blogs, WUWT does not censor opposing points of view. Instead, it allows the marketplace of ideas to winnow the truth from fiction. That is a major difference, and it is the primary reason why WUWT is the top science site on the internet.
This thread set me thinking: How would a physicist measure ice loss or ice gain in the antarctic?
Here is the experiment I would do:
I would sink GPS modules to the bedrock, as many as needed to follow the rock contours as mapped by radar already. Use underwater GPS.
Sinking instruments long way into the ice has been used by the IceCube experiment in the antarctic, and before that by AMANDA.
I would have GPS on the surface following the visible contours. Or use the satellite measurements of the surface, if not too many errors are introduced.
I would monitor both in short time intervals, creating the two surfaces, bottom, top, subtracting and integrating to get the volume occupied by ice.
It does not matter if isostasis changes the bedrock contour or magma or tectonic motions. It does not matter if pressure changes in the atmosphere. The volume will be the ice volume.
If the volume occupied by ice over a year diminishes, the ice will be diminishing.
If it increases, it will be increasing.
All this modeling with resolutions of hundreds of kilometers, lots of unknown forces entering and coming out with millimeter maps is more like playing video games than serious study.
In the one study out of the pay wall I found, http://thingsbreak.files.wordpress.com/2009/10/increasing-rates-of-ice-mass-loss-from-the-greenland-and-antarctic-ice-sheets-revealed-by-grace.pdf
the author plays with a fit that has a lot of moments, and when the fit does not agree with his assumptions he uses satellite lazer measurements .
We use monthly GRACE gravity field solutions
generated at the Center for Space Research at the University
of Texas [Tapley et al., 2004], for 80 months between
April 2002 and February 2009, to estimate Antarctic and
Greenland mass variability. Each gravity solution consists
of spherical harmonic (Stokes) coefficients, Clm and Slm,
up to l, m 60. Here, l and m are the degree and order of
the harmonic, and the horizontal scale is 20,000/l km.
The GRACE C20 coefficients, which are proportional to the
Earth’s oblateness, show anomalously large variability, so
we replace them with values derived from satellite laser
ranging [Cheng and Tapley, 2004
Doug McGee
In the early part of the last century, an obscure German patent clerk with a low high school GPA had the audacity to write papers about nuclear physics. Can you imagine?
Chris Noble
How much glacial ice loss do you think has occurred 300km off the coast of East Antarctica?
“Steve Goddard”…
BA
No matter how hard you try to ignore it, this GRACE data has been used over and over again as evidence of widespread Antarctic melting. Like this article in the Washington Post from four years ago.
But you didn’t write your post to attack whatever the Washington Post said, you wrote it to attack an article by Chen et al. which you had not read. You would now like to distract attention from your mistakes, but they’re still there in living color.
I overlaid the Antarctica summer temperature map on the GRACE “melt” map,
Did a single one of the “skeptics” who praised your post, and who affect to know something about science, catch this basic misstatement of what GRACE does?
It is of course disgraceful when AGW types ascribe all climatic and geographical changes to global warming, whether or not the evidence justifies it. The gravitational anomaly evidence does not justify any significant claims about ice loss, because there are no experimental data adequate to distinguish ice loss from tectonic changes – only models in which the errors are of the same magnitude as the anomalies reported. It would be entirely consistent with the Grace data to assume that the ice thickness had not changed at all anywhere (though other evidence might contradict this). Anna’s point – which both sides seem to be ignoring – is quite sound. It is also quite clear that changes in the Antarctic can occur that are not caused by “global warming”; and it is not always clear what the dependence – or even the sign of the dependence – on global temperatures may be. Would a warmer climate on balance mean more ice in Antarctica, or less? We don’t know. There are too many competing effects.
However, it is also unacceptable to insist that AGW could not have such and such an effect, or that such and such a phenomenon could not occur, when the evidence does not justify such contentions either. In the present thread there seems to be a concerted effort to deny that various well-known effects are even possible. In particular, to deny that you can get rapid ice loss even when the temperatures are far below zero, and to deny that glaciers can respond quickly to changes a considerable distance away. Both the empirical evidence and the basic physical theory that shows how this works are being ignored. This is behaviour worthy of AGW ideologues. I expected better of skeptics.
I will try again to explain, in terms of simple basic physics, how the flow velocity of an ice sheet can change almost instantly in response to changes at its seaward end. Suppose the end of the sheet is grounded ice, dug into the sea bottom along the shore. This has the effect of a dam, holding back the glacier trying to slide towards it; even if the ice is still moving, the friction or resistance at the base slows it down – creating a positive pressure on rest of the glacier behind. Now suppose that warm water from the sea (or elsewhere) melts away the base up the incline towards the shoreline (or beyond). The once grounded ice is now either floating or highly lubricated and no longer resists the forward motion. The positive pressure of the dam disappears, replaced by a negative pressure (tension) from the weight of the end section trying to slide down the slope. The pressure change, causing the glacier to accelerate downslope, propagates at the speed of sound through the entire contiguous mass of the glacier. If the tension causes a part of the end to break off (calve), the opposite happens; the glacier slows as the pressure wave speeds up through it. The glacier will periodically speed up and slow down as the tension ramps up then suddenly drops as another chunk breaks off.
Depending on the details of the ground and ice topographies, warming at the seaward end can cause either a net increase in flow rate or a net reduction. Similarly, depending on the relative gradients of ground and ice sheet, increases in flow velocity can cause either a net increase in ice thickness (at a given location) or a net decrease, and vice versa. The assumption that coastal warming must cause an increase in ice flow from the interior is false; but so is the assumption that it cannot.
OK, here it is hidden away from the pay wall:
ftp://ftp.csr.utexas.edu/pub/ggfc/papers/ngeo694.pdf
I have to say that all these supercilious people lecturing us are really very bad mannered, and do not even make the effort of finding if their references exist outside of the pay wall.
Comments:
The abstract reflects the content, as it should.
In agreement with an independent earlier
assessment4, we estimate a total loss of 190+/-77 Gt yr-1, with
132 +/- 26 Gt yr-1 coming from West Antarctica. However, in
contrast with previous GRACE estimates, our data suggest that
East Antarctica is losing mass, mostly in coastal regions, at a
rate of -57+/-52 Gt yr1, apparently caused by increased ice
loss since the year 2006.
Already from the abstract we see that east antarctica is out of the picture.
a rate of -57+/-52 is nonsense. I come from a particle physics background. We publish a new effect if it is 4sigma from the error.
A possible effect if it is 3 sigma, and an interesting effect if it is 2sigma. 1 sigma is noise.
The total is interesting, but not to crow about, and we see it is really that because west antarctica is averaged in, that the total turns interesting.
West Antarctica is an effect statistically significant, but this is well known and not a matter of discussion here.
using 79 monthly samples of the most recent GRACE
release-4 (RL04) spherical harmonic solutions for the period April
2002 to January 2009.
For people who are saying this is data. It is not. It is spherical harmonic solutions for the given period, i.e. a model. Also fig 2: forward modeling scheme
En plus, they are manipulated at taste.
from “methods”
After
filtering, a global gridded (11) surface mass-change field is estimated from each
of the 79 solutions, including harmonics up to degree and order 60. Long-term
variability of low-degree zonal harmonics (C20;C30;C40) removed during GRACE
data processing was restored.
Interesting that C20 is restored in contrast to the previous work I found out of the pay wall.
In summary, peer review has fallen on its face here. One cannot claim 1 sigma as an effect, now way. It should have been stressed that it is noise, both in the abstract and in the content. One cannot include a 4 sigma effect with a 1 sigma effect in order to create a headline.
The scientific level of Nature is plummeting faster than west antarctica ice.
stevengoddard says:
July 2, 2010 at 4:45 am
Doug McGee
In the early part of the last century, an obscure German patent clerk with a low high school GPA had the audacity to write papers about nuclear physics. Can you imagine?
Really, who was that and what did he write about?
First WUWT thread I’ve read that requires a bibliography! 🙂
===============
Glacier acceleration and thinning after ice shelf collapse in the Larsen B embayment, Antarctica,
Scambos, 2004
http://www.nasa.gov/pdf/121653main_ScambosetalGRLPeninsulaAccel.pdf
Warm ocean is eroding West Antarctic Ice Sheet
Shepard, 2004
http://geo-w2.austin.utexas.edu/courses/387H/Lectures/Shepard_04.pdf
(reg) Retreating glacier fronts on the Antarctic Peninsula over the past half-century
Cook, 2005
http://www.mmjb.info/cgi/reprint/308/5721/541.pdf
(reg) Snowfall-Driven Growth in East Antarctic Ice Sheet Mitigates Recent Sea-Level Rise
Davis, 2005
http://www.sciencemag.org/cgi/content/abstract/308/5730/1898
??? Changes in ice dynamics and mass balance of the Antarctic ice sheet
Rignot, 2006
http://rsta.royalsocietypublishing.org/content/364/1844/1637.abstract
Mass balance of the Antarctic ice sheet
Wingham, 2006
http://www.cpom.org/research/djw-ptrsa364.pdf
$$$ Widespread acceleration of tidewater glaciers on the Antarctic Peninsula
Pritchard, 2007
http://www.agu.org/pubs/crossref/2007…/2006JF000597.shtml
(reg) Recent Sea-Level Contributions of the Antarctic and Greenland Ice Sheets
Shepherd and Wingman, 2007
http://www.sciencemag.org/cgi/content/abstract/315/5818/1529
Recent Antarctic ice mass loss from radar interferometry and regional climate modelling
Rignot, 2008
http://www.phys.uu.nl/~broeke/home_files/MB_pubs_pdf/2008_Rignot_NatGeo.pdf
$$$ Changes in West Antarctic ice stream dynamics observed with ALOS PALSAR data
Rignot, 2008
http://www.agu.org/pubs/crossref/2008/2008GL033365.shtml
$$$ Ice sheet mass balance and sea level
Allison, 2009
http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=6215004
Accelerated Antarctic ice loss from satellite gravity measurements
Chen, 2009
ftp://ftp.csr.utexas.edu/pub/ggfc/papers/ngeo694.pdf
Ice-flow velocities on Rutford Ice Stream, West Antarctica, are stable over decadal timescales
Gudmundsson, 2009
http://www.igsoc.org/journal/55/190/t08J127.pdf
Extensive dynamic thinning on the margins of the Greenland and Antarctic ice sheets
Pritchard, 2009
http://www.astroscu.unam.mx/~binette/atcag/Other_articles/hamish_melt_antarctic.pdf
Regional ice-mass changes and glacial-isostatic adjustment in Antarctica from GRACE
Sasgen, 2009
http://edoc.gfz-potsdam.de/gfz/get/10449/0/ca70a6da5cdc713937c5062aee09259a/10449.pdf
$$$ Increasing rates of ice mass loss from the Greenland and Antarctic ice sheets revealed by GRACE
Velicogna, 2009
http://www.agu.org/pubs/crossref/2009/2009GL040222.shtml
===============
Book: The Physics of Glaciers
On Google Books
Video: Variegated Glacier 1983: Arrival of the Surge on the Lower Glacier
Chart: Ice basin flow rates (Rignot): http://lima.nasa.gov/img/rignot_basins.tif
===============
Steve, you will find the actual papers your news items reference included in the above list, not the news articles themselves.
I give permission and encourage moderators to fix or add links to the above list, as they see fit.
Doug McGee says: July 2, 2010 at 3:57 am
“Because outsiders bring science here, it doesn’t make this a science blog, per se.”
Science is not defined by who does the research, analysis and arguing, how many degrees they have, from which schools, their intelligence, or lack thereof, whether they consider themselves to be an outsider, insider, or otherwise, their agenda, their tone, etc., “Science (from Latin: scientia, meaning “knowledge”) is a systematic enterprise of gathering knowledge about the world and organizing and condensing that knowledge into testable laws and theories.” “It includes the use of careful observation, experimentation, measurement, mathematics, and replication — to be considered a science, a body of knowledge must stand up to repeated testing by independent observers. The use of the scientific method to make new discoveries is called scientific research, and the people who carry out this research are called scientists.”
http://en.wikipedia.org/wiki/Science
Thus, whether you like it, or whether you admit it, doth not matter, you are participating in one of the most powerful vehicles for scientific exploration that humans have developed to date. Unless of course you would like to argue this point further, in which case, bring it, as I am always open to “repeated testing by independent observers”…
Unofficial “Amazing Grace” bibliography.
http://rhinohide.wordpress.com/2010/07/02/wuwt-amazing-grace-unofficial-bibliography
I did try to publish this here, but there are too many links and will require moderator rescue. If you see a long bibliography before this post, kindly disregard this one.
@Just The Facts
July 2, 2010 at 9:09 am
You need not lecture what science is. That is not the way to convince the majority of Americans. You need newspaper articles, blogs, books, journals, lectures, ordinary teachers, to convey this message in an understandable language.
A science article or a science blog is mostly ABOUT research done by scientists, and WUWT authors usually have more background than most writers of scientific articles. That is why it was awarded as the most popular science blog by definition. That’s a fact whether you like it or not.
Anna V, you have repeatedly elaborated that the GRACE data cannot distinguish between the dynamics of the ice and the dynamics of the ground beneath it, that is influenced by unmeasured tectonics, isostasy, and magma movements etc.
Smokey and I have also severally asked David and Robert, (they having been the most obviously antagonistic on this thread), to respond to your elucidations. (relating to the paradoxes raised by Steve). However, one of them has claimed to have “gone fishing” and the other went silent. However, there are a bunch of lesser antagonists that have also remained silent, whilst raising red-herrings. (straw-men)
Now why would that be I wonder?
Anna V., many thanks for the link to the paper. Upon reading it, I was struck by the “jumpiness” of the data. According to their results, the mass of the ice can increase by 50–150 mm of water equivalent in one month, and then drop by the same amount the very next month, both in the winter and in the summer … somehow, I kinda misdoubts that.
And that is after smoothing it with a 300 km Gaussian filter, so there is no telling how jumpy the underlying data is.
These jumps can’t be from sea ice breaking off at the edge. That doesn’t change the mass one bit, because the ice displaces the equivalent amount of water. So there would be no mass change from that.
Like I said, this seems like kind of a blunt tool for the 1-millimetre scale purpose to which they have applied it.
Phil. says:
July 1, 2010 at 8:14 pm
Smokey says:
July 1, 2010 at 6:33 pm
Steve:
Also, regarding the question of mass conservation, it seems that since a glacier can expand and contract at various points [since it isn’t flowing through a pipe], calving would have even less effect at the source. If there is any measurable effect at all, which I still question — particularly as it applies to Chris Noble’s assumption regarding the primary influence of calving on a glacier’s flow speed.
It’s termed ‘continuity’ in fluid mechanics, if the end of a glacier flow increases the flow of ice nearer the source must also increase or the glacier will break.
—…—…—
I don’t know if you noticed or not [ /sarcasm, ] but glaciers are broken. You can make no assertions or assumptions about glacier movement (top down – or relating the movement at the terminus due to more (or less) snowfall at the head, or bottom up – removal of mass at the bottom affecting thickness (or thinness) at the top area) being any faster than the actual movement of the glacier mass itself.
Your assumed “rate of information flow” – also mentioned a few posts above claiming a “speed of sound” transmission – is dead wrong. Or, more properly, correct only in a solid. Which a moving glacier is most emphatically not. Each glacier block (which is a solid) is separated by a crevasse or crack as you follow a glacier upstream. Each block changes daily and monthly as it flows – but few are more than 50 to 100 meters long. Each crack IS a “break” in the glacier.
Glacier movement is further compounded (slowed) by the nature of the three main styles:
Mid-continent (no movement downhill since the glacier mass is trapped between mountain ranges – this is the entire central “valley” of Greenland and 93 percent of the Antarctic continent
Alpine: Steeply but relatively constantly-slowed glacier masses with essentially no terminal “restraint: Melt water flows down the resulting valley unimpeded away from the glacier. Greenland Alpine-style glaciers are only found in limited area
Coastal terminus: Short, typically coming from a sloped alpine-style glacier, but terminating onto a free-water surface. Glacier tip extends over the underlaying water for varying distances, and breaks off forming icebergs to move away from the tip and melt off.