Why the Greenland and Antarctic Ice Sheets are Not Collapsing

http://svs.gsfc.nasa.gov/vis/a000000/a003400/a003455/fullGreenlandElevChg.8188_web.png

Image: NASA Goddard Spaceflight Center SVS

Cliff Ollier

School of Earth and Geographical Sciences, The University of

Western Australia, Crawley, WA 6009, Australia.

Colin Pain

Canberra City ACT 2601, Australia.

Global warming alarmists have suggested that the ice sheets of Greenland and Antarctica may collapse, causing disastrous sea level rise. This idea is based on the concept of an ice sheet sliding down an inclined plane on a base lubricated by meltwater, which is itself increasing because of global warming.

In reality the Greenland and Antarctic ice sheets occupy deep basins, and cannot slide down a plane. Furthermore glacial flow depends on stress (including the important yield stress) as well as temperature, and much of the ice sheets are well below melting point.

The accumulation of kilometres of undisturbed ice in cores in Greenland and Antarctica (the same ones that are sometimes used to fuel ideas of global warming) show hundreds of thousands of years of accumulation with no melting or flow. Except around the edges, ice sheets flow at the base, and depend on geothermal heat, not the climate at the surface. It is impossible for the Greenland and Antarctic ice sheets to ‘collapse’.

In these days of alarmist warnings about climate warming, the ice sheets of Greenland and Antarctica have an important role. Many papers have described their melting at the present times, and dire predictions of many metres of sea level rise are common. Christoffersen and Hambrey published a typical paper on the Greenland ice sheet in Geology Today in May, 2006.

Their model, unfortunately, includes neither the main form of the Greenland Ice Sheet, nor an understanding of how glaciers flow. They predict the behaviour of the Ice Sheet based on melting and accumulation rates at the present day, and the concept of an ice sheet sliding down an inclined plane on a base lubricated by meltwater, which is itself increasing because of global warming. The same misconception is present in textbooks such as The Great Ice Age (2000) by R.C.L. Wilson and others, popular magazines such as the June 2007 issue of National Geographic, and other scientific articles such as Bamber et al. (2007), which can be regarded as a typical modelling contribution. The idea of a glacier sliding downhill on a base lubricated by meltwater seemed a good idea when first presented by de Saussure in 1779, but a lot has been learned since then.

In the present paper we shall try to show how the mechanism of glacier flow differs from this simple model, and why it is impossible for the Greenland and Antarctic Ice Sheets to collapse. To understand the relationship between global warming and the breakdown of ice sheets it is necessary to know how ice sheets really work. Ice sheets do not simply grow and melt in response to average global temperature. Anyone with this naïve view would have difficulty in explaining why glaciation has been present in the southern hemisphere for about 30 million years, and in the northern hemisphere for only 3 million years.

Read the complete paper here

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Ray

I think the AGWiers underestimate THE POWER OF HYDROGEN BONDS.
When you think that a 10 cm thick ice bridge can support a fully loaded 10 wheels truck, imagine how well the ice of glaciers that have been compressed for millions of years holds itself together because of THE POWER OF HYDROGEN BONDS!
It’s like, when I stick a foot out of my bed, my whole body does not slide down to the floor.

Basic science will trump alarmism if the “pack” doesn’t run off the cliff like a bunch of lemmings, first.

Gerry

Ollier and Pain should submit their paper for participation in the upcoming Copenhagen conference, even though the odds are that it will be rejected, and they will be “uninvited.”
In fact, I would like to see all the authors of recent papers deviating from the AGW dogma submit them. If most or all are rejected, an international class action suit should be filed against the IPCC.
Very likely an argument would be made that they missed an early submission deadline, in which case they can protest late acceptance of all pro-AGW submissions.

ak

Thrust faults in the earth are a great example of gravity and a descending plane NOT being necessary to cause movement of a semi-rigid (rock moreso than ice) body.
Fluids providing lubrication at the base of a thrust fault will make it easier for the fault to move though. The same can be said for the liquid water at the base of an ice sheet.
The force driving a thrust fault is tectonic forces. That driving force behind glacier movement is the weight of the ice itself. Much like a bowl overfilled with water, the water will settle until it is at it’s lowest point and then any extra will exit over the basin. Same goes for ice, albeit at a much longer time-frame.
As the ice thins, the basin, which is created by the weight of the ice itself, will begin to rebound making it less effective as a basin.

crosspatch

I read that yesterday. There is one area where the ice sheet has regularly “collapsed” and that is a portion of the WAIS. The intervals … somewhere around 100K years, would seem to indicate that it is somewhat in sync with glaciation intervals. The notion being that natural melt at the base due to geothermal heating causes a layer of muddy goo and then some trigger, possibly seismic, causes liquifaction of the underlying material and the glacier rides out on a giant mudslide. This notion comes from study of sediment stratification that would seem to indicate larges flows of material at 100K intervals and alternating periods when parts of the ocean floor are under an ice covered surface and a surface apparently free of ice.
Also, happened to notice that the Wikipedia article on the WAIS includes this:

Warming
The West Antarctic ice sheet has warmed by more than 0.1 °C/decade in the last 50 years, and is strongest in winter and spring. Although this is partly offset by fall cooling in East Antarctica, this effect is restricted to the 1980s and 1990s. The continent-wide average surface temperature trend of Antarctica is positive and significant at >0.05°C/decade since 1957.[14]. This warming of WAIS is strongest in the Antarctic Peninsula.

Footnote 14 points to the Steig paper published in Nature that has been shown to be faulty in its conclusions. Maybe someone with more authority than I would care to correct that portion of the article.

hunter

But it is vital for the AGW promotion industry to be free to ’emotionalize’ about threats, espcially if the threats are not real. and since none of the aGW threats are, in fact, real, ’emotionalization’ is even more important.
After all, the mission of AGW promotion, to save us from non-existant threats, is more importnat than any single fact or accurate statment.

bill

Loss is at margins. Central south is growing:
http://img440.imageshack.us/img440/2052/greenlandicesheet.jpg
The global warming doomsday writers claim the
ice sheets are melting catastrophically, and will
cause a sudden rise in sea level of many metres.

Ice sheets are melting catastrophically! I’ve heard few if any people say this. Perhaps they say it could happen in worst case scenarios but not NOW.
I think it would be hard to find statements in IPCC report that claim catastophic melting IS occurring!!!

Fred from Canuckistan . . .

Volume of ice in Greenland Ice Sheets . . . . 26,000,000+ km3
Average annual melt . . . . 200km3
Melt as % of volume . . . 0.00077%
Years required to melt Greenland Ice sheet at current rate . . . 130,000 years
Repent !
The End is Nigh

Bill Illis

There is also a new paper using the most detailed measurements and modeling for the Greenland ice sheet and it shows that the mass balance of the ice sheet is still increasing, not melting.
Total snow accumulation was about 700 GigaTons in 2008 and total melt run-off, ablation and discharge was about 450 GigaTons.
There is a small net loss along the southwest coast and in some small areas in the north, but the vast majority of Greenland is still gaining ice (although the rate of increase is declining).
https://eng.ucmerced.edu/people/rbales/CV/PubsP/120

ak

Here is a cross-section of Greenland from GEUS (the Danish Geological Society) which clearly shows easily 95% of the ice on Greenland exists above sea level and the basin’s edge.
http://www.geus.dk/viden_om/voii/ilulissat-uk/goii03_fig03_large_uk.jpg
Ice will flow and it will flow out of the basin!

A subtle, but very effective, part of the ecotheist’s propaganda about Greenland’s icecaps – particularly when you ignore the geological principles detailed above – is the Mercator projections in hundreds of thousands of classrooms across the countries.
The type of projection – seldom explained and not well-drawn anyway when Antarctica is usually cut-off, but Greenland prominently increased – exaggerates how small Greenland actually is. At 1.6 million km^2, it is the same size as Saudi Arabia, much smaller than Australia.
Yet there is it, seemly bigger than South America – hanging like an icy sword of death over the innocently green rest of the world.

Jeff in Ctown

Great read. I learned a lot about ice crystals and glacier flow. Now I am an expert and can make fun of all the people talking about melting ice caps.

Slartibartfast

More like 2.2 million km^2. But yes, just about the size of Saudi Arabia.

Slartibartfast

Here is a cross-section of Greenland from GEUS (the Danish Geological Society) which clearly shows easily 95% of the ice on Greenland exists above sea level and the basin’s edge.

That’s nice. It doesn’t mean that it’s going to slide off, though. In fact, if if the ice sheet is similarly secured in the N-S direction, it means that it’s NOT going to slide off. It’d have to tip off, and that’s not going to happen. Sure, it could eventually melt away, or something could happen to otherwise accelerate the rate at which ice leaves the ice sheet, but there doesn’t appear to be any imminent catastrophe, there.
Oh, and also: that’s a cross-section, not the cross-section, so I’m not sure what your point is. There may be more secure containment of the ice sheet, elsewhere.
Finally, the fact that the vertical scale is greatly exaggerated (factor of about 80) makes things appear much less stable than they actually are.
So: your point is what, again?

NastyWolf

ak (09:43:31) :
“Here is a cross-section of Greenland from GEUS (the Danish Geological Society) which clearly shows easily 95% of the ice on Greenland exists above sea level and the basin’s edge.”
Nice choice of dramatic scale. Glacier should be about 200km thick if that picture would correspond with reality.

George E. Smith

“”” ak (09:25:30) :
Thrust faults in the earth are a great example of gravity and a descending plane NOT being necessary to cause movement of a semi-rigid (rock moreso than ice) body.
Fluids providing lubrication at the base of a thrust fault will make it easier for the fault to move though. The same can be said for the liquid water at the base of an ice sheet.
The force driving a thrust fault is tectonic forces. That driving force behind glacier movement is the weight of the ice itself. Much like a bowl overfilled with water, the water will settle until it is at it’s lowest point and then any extra will exit over the basin. Same goes for ice, albeit at a much longer time-frame.
As the ice thins, the basin, which is created by the weight of the ice itself, will begin to rebound making it less effective as a basin. “””
Lemme see if I have this right; you say that it is the weight of all of that ice (say in Greenland) that will squish the ice to flow out of the basin; but that as the ice thins (from getting squshed out by the great weight of all that ice) the basin bottom will rise; and presumably squish some more ice out.
So now exactly what thickness of ice is stable, so that it isn’t losing ice by basin bottom rebound, nor is it gaining ice thickness, and squishing it over the rim of the basin ?
What is the chance that the present thickness of Greenland ice, is at that stable level so it is neither squishing ice over the rim of the basin, nor having the basin bottom rebound and ejecting the ice. It does seem yo have been there for a good ling time, and not in any great hurry to go some place else.

ak

@NastyWolf – there are TWO scales on the diagram! Or rather, I should say, the ice sheet is only 18km wide! lol

Dave

“It’d have to tip off, and that’s not going to happen”
IT COULD…If you believe the previews to the movie 2012

Deanster

AK …
For the Basin to push back up .. it would occurr in geologic time .. that’s thousands to millions of years.
Thanks for supporting the featured authors position that the Greenland and Anarctic Ice sheets are not going to fall in to the sea and drown us all any time soon.

Jeff in Ctown

ak (09:43:31) :
“Here is a cross-section of Greenland from GEUS (the Danish Geological Society) which clearly shows easily 95% of the ice on Greenland exists above sea level and the basin’s edge.”
If you had read the paper, you would know that the only real question is “does the plastic zone of the ice cap extend up beond the high mountains along the coast.
Try reading the material before trying to argue against it.

Merrick

So, NastyWolf, you wanted them to draw it to scale so that it was 10 inches wide and 1/100 inch thick? And what would that teach us? Better yet, should it be a 10 inch arc representing the actual curvature of the Earth but still 1/100 inch thick?
Or perhaps you’re suggesting that the 600 m tall heights to the West and 1700 m tall heights to the east aren’t going to hold back the glaciers becuase the slope is too low?
I just want to make sure I understand your criticism.
Thanks.

Slartibartfast

It’s for certain that the given profile doesn’t cross Gunnbj&#248rn Fjeld, for instance, which has a bunch of peaks over 3500m.

George E. Smith

“”” ak (09:43:31) :
Here is a cross-section of Greenland from GEUS (the Danish Geological Society) which clearly shows easily 95% of the ice on Greenland exists above sea level and the basin’s edge.
http://www.geus.dk/viden_om/voii/ilulissat-uk/goii03_fig03_large_uk.jpg
Ice will flow and it will flow out of the basin! “””
Well not so fast there; the link above is to a two dimensional vertical plane section; but the Greenland ice mass is actually a three dimensional object.
Your picture creates the fictitious illusion, that that central 3 km thick pile of ice is going to extrude to the left, and all fall off the left edge of the drawing; whereas in fact it is going to spread in three dimensions, to an ever increasing perimeter, so the outward driving pressure keeps falling as the ice approaches the coast.
According to your picture the basin depth at the left end is about 500 metres deep; yet the central bulge is only six times that thickness. That is hardly a highly stressed structure; and I would venture that the bottom of the ice is thoroughly locked to the rock base by the topography of the basin; so the only way for that ice mass to move is by extrusion of the ice itself; and the ice is crystalline; so it is not exactly a fluid; Also the temperature of most of that ice is so far below freezing, even the change in freezing point due to pressure is not going to melt the bulk of that ice; so only at the edges would there be any liquid lubrication flow.
I would venture that any structural analysis of such a monolith would show that it is a robustly stable object; and as fast as ice can get lost from the perimeter, it will be replaced by precipitation; and if in fact temperatures get warmer, that precipitation in the middle of Greenland would be expected to increase, not decrease (see Wentz et al SCIENCE July 7 2007).
Greenland ice sheet collapse is just a red herring; same goes for Antarctica; it hsn’t collapsed in over 700,000 years dsepite going through 8 ice ages and interglacial warm periods.

Slartibartfast

Oh, crap. Some blogcomments don’t interpret the codes properly.
&uoslash;?

Ray

One single meteor smashing in the ocean would cause more damage instantly than any catastrophic melting of all ice bodies of earth, even if it melted over a few years… which obviously will never happened. So, where should we put money to save the earth?

ak

@Slartibartfast, I never said anything about sliding, only flowing. That’s how ice behaves. It’s talked about in the linked paper, and in many Glacialogy textbooks. Not knowing that would logically lead to your second question about containment. Ice simply flows around the mountains.
But just to entertain the idea that it is a single cross-section… well, it makes sense since I only linked one image. Regardless, if I were trying to ‘tip the scales’ in my favor, I would not have put a large mountain range in the east, but that’s just where this cross-section was taken. Fact is, it is the only cross-section I could find 🙂

Jeremy

Sadly, it has now become necessary to publish papers simply to re-emphasize basic science, refute complete and utter nonsense and remind everyone about the facts.
It indicates the incredible power of the propaganda that Ecofascists wield in our schools, in the fields and in the streets, in the hills and on the beaches, striking at the very heart of our industrial civilization. Many old and famous Institutions have fallen or may fall into the grip of the AGW and all the odious apparatus of Ecofascist rule.

ak

This image shows surface velocities of ice in Antarctica (mostly, it doesn’t take into account up and down movement) and shows that the ice flow does not move as a uniform block (for those still clinging to the ‘sliding’ canard) and will speed up closer to the margins due to lessening bounding ice on one side.
http://en.wikipedia.org/wiki/File:Antarctica_glacier_flow_rate.jpg
from: http://en.wikipedia.org/wiki/Ice_sheet_dynamics
I agree with the author in the general point that most of the population may not have a strong grasp of the actual mechanisms of glacier behaviour, but only addressing the negligible aspect of glacial movement against bedrock is not doing much for educating that population.

Nogw

How do gwrs. explain that glaciers keep advancing upwards from its basins?; the only explanation is that they are growing up, as in antarctica. The well known , and previously explained here in WUWT, phenomenon of the “ice cube dispenser machine”.

ak

@Slartibartfast, @NastyWolf, my apologies… I misread your comments about the exagerated scale as non-existent scale. It’s common in geology to exaggerate the vertical axis – it would be kind of hard to view an image that is 10 million pixels wide 🙂
I’ve linked to an image which shows actual values for the speed of glacial movement at the surface. While, it may take a 100 years for ice at the middle to flow to the edge, it is still moving and doesn’t rely on basal flow.

Nogw

This paper explains what was already explained, in detail, by Ian Plimer in his book “Heaven and Earth”.

tty

crosspatch (09:26:44) :
Those recurring collapses of the WAIS are an AGW factoid. There is no credible evidence for them, no sudden d18O jumps, no IRD layers in the Southern Ocean, no abrupt sea-level rises anywhere.
On the other hand there is now strong evidence that the WAIS has not been much smaller than at present since MIS 31, about 1,07 million years ago. During this exceptionally warm interglacial it was apparently at least much reduced, and temperatures in the Ross Sea significantly warmer than at present (see for example Wilson, G. S., et al. 2007. Preliminary chronostratigraphy for the upper 700 m (late Miocene-Pleistocene) of the AND-1B drillcore recovered from beneath the McMurdo Ice Shelf, Antarctica. USGS Open-File Report 2007-1047, http://pubs.usgs.gov/of/2007/1047/ and references therein).
ak (09:25:30) :
That is an absurd comparison. Movements on faults are driven by tectonic forces. There are no tectonics in ice-sheets, they are moved exclusively by gravitation. Also while the basin will undoubtedly rebound if the ice-sheet thins, it will not disappear since there are mountain-chains (up to 3700 meters high) around most of Greenland. This rather unusual configuration which is due to the way the north Atlantic opened is probably the main reason Greenlands ice-sheet is so uniquely stable compared to the Scandinavian and Laurentian ice-sheet. Furthe it is not at all clear that the ice will become thinner as it retreats. Once it has retreated far enough that it can no longer calve into the sea, it can only lose mass by peripheral melting which is a much slower process. This means that the ice-dome becomes steeper and higher. There is evidence that the northern dome of the Greenland Ice was actually a few hundred meters higher during the last interglacial, when the ice area was reduced.
ak (09:43:31) :
And that image you link to is somewhat misleading since the vertical scale is exaggerated about 35 times. The ice cap is actually very very flat. The map on page 10 of:
http://www.geus.dk/publications/bull/nr14/nr14_p01-13_A1b.pdf
gives a much better picture of the subglacial topography. As you can see there, it is only a very small part of the Greenland ice that could even theoretically “slide into the sea”. Also if these remarkable ice-slides are possible, why didn’t they happen in Scandinavia during the last deglaciation, where the ice retreated up-slope and there were handy seas to slide into on both sides of the divide?
In short the ice will indeed flow, but very slowly, like it always does, and it definitely won’t flow uphill!

Bill Sticker

Fred from Canuckistan . . .
Well, yes. The end will be nigh……..eventually. Maybe. Possibly, but not just yet.

John G. Bell

As much as I’d like the world to not see another Ice Age while humans exist it looks like we can expect one in a few thousand years if not sooner. If you look at the climate record it seems overdue. So it isn’t reasonable to talk about 130,000 years of melting. This melting happens only a small fraction of the time.
If you believe more CO2 is a problem, don’t worry too much about that. We won’t be able to keep enough CO2 in the air to prevent the next Ice Age and once the oceans cool they will suck up CO2 rapidly. And when we get into an Ice Age we stay in it for a long long time.
Our money might be better spent on figuring how to breed hairy children with massive brows. When the time comes, they will appreciate it.

morganovich

AK-
if the ice is a couple hundred thousand years old, and it has not slid off yet, why would it do so now? temperatures were much warmer in greenland during the medieval period, the roman period, and from there almost always at at least a degree warmer all the way back to the Holocene climate optimum which was 2-3 degrees C warmer than the present and lasted 3000 years.
what’s so magic about now that suddenly the ice will alter behavior? might it shrink from 1850 to now, sure. in 1850, the little ice age was ending. that was the coldest period in the last 9000 years. but it’s not even as warm on greenland now as it was when the vikings settled there. i don’t recall the vikings getting pushed into the sea by a sliding ice sheet. i recall them getting frozen out by expanding glaciers and dropping temperatures that made the settlement untenable.
if you’re going to claim: “this time is different” and this warming will do what others didn’t, you’re going to need to show us WHY it’s different.

ak

@Deanster I didn’t use timescales, because I felt like most people would know what they are, but good point. Yes, I agree with the author that there won’t be a big “kerplunk” episode anytime soon – continental glaciers falling into the sea! :/
@Jeff in Ctown, see my later comments (updates around here are slow – why isn’t this a forum?) specifically (“I agree with the author in the general point that most of the population may not have a strong grasp of the actual mechanisms of glacier behaviour, but only addressing the negligible aspect of glacial movement against bedrock is not doing much for educating that population.”)
@George E. Smith Yes, it’s 3-dimensional in reality and that movement can be clearly seen in the Antarctic image I linked to. I can’t find a similar velocity map for Greenland. And ice, even in it’s crystalline form, will not act as a solid body.
@tty Good comments. I’m kind of at a loss about these ice slides everyone is talking about. There is no evidence for them happening before, but everyone is happy to argue against them! 🙂

vanderPool

John G. Bell (11:54:08) :
Priceless. . .

maksimovich

Interesting paper in nature
“Most high-resolution climate reconstructions for the past millennia have focused on Northern Hemisphere land records. Ocean reconstructions have to date been rare and, critically, have missed the most recent centuries, preventing a comparison with the observational records. A new reconstruction of sea surface temperatures for the Indo-Pacific warm pool now provides a decadally resolved record that spans the last two millennia and overlaps the instrumental record, enabling both a direct calibration of proxy data to the instrumental record and an evaluation of past changes in the context of twentieth century trends. The data show that while recent decades have been anomalously warm, they are statistically indistinguishable from temperatures prevailing during the Medieval Warm Period from around AD 1000 to AD 1250 ”
http://www.nature.com/nature/journal/v460/n7259/edsumm/e090827-06.html
Ubiquitous “global MWP” is against the “party line”

Slartibartfast

While, it may take a 100 years for ice at the middle to flow to the edge, it is still moving and doesn’t rely on basal flow.

Oh, sure ice flows. It flows because it’s continually being weighed down by new snowfall, as well as by its own upper layers. If you know this, then you know that ice flows all of the time, and that all warmer weather might do is cause it to melt a bit faster.
If basal flow is irrelevant, why show the cross-section?
I made the comment about cross-section location because I was confused as to what your point was, and now I’m even more confused. Is the shape of the terrain under the ice sheet important, or not important, in your opinion?
I’m not trying to be difficult; I am simply attempting to understand what it is you’re trying to say, and how it relates to the main post.
Thanks in advance!

crosspatch

“Those recurring collapses of the WAIS are an AGW factoid.”
The paper I read (and can not locate, though I admit I am busy with other things right now and haven’t looked with any diligence) wasn’t a “warmest” paper at all. On the contrary, the conclusion was that “collapse” of the sheet in that specific area was a normal cyclical event unrelated to “global warming”. The notion being that either seismic activity or possibly geothermal/volcanic conditions combined with the natural slope of that specific area would be enough to explain it and it wouldn’t be associated with climate change except possibly in periods when the glacial mass might be better optimized for the failure to occur, which might be related to long-term climate changes. These changes would be regular cyclical changes and not anything induced by humans.

Slartibartfast

Our money might be better spent on figuring how to breed hairy children with massive brows.

If you’ve ever seen my younger brother, well…success!

rbateman

John G. Bell (11:54:08) :
Not at all unlike the Big Earthquake California or the Mississippi expects.
Or the next supervolcano.
Or when the next asteroid or comet comes sailing stright for the planet.
The attention span is the same or less than the surveillance that currently missed the impact on Jupiter.
Another overdue event.
47 days and counting.
So, while attention is focused on a ‘fake out’ emergency, things that are really happening or overdue to happen go unnoticed.

David L. Hagen

Warming alarmists can be certain Greenland and Antarctic ice sheets will evaporate – in 1,000,000,000 years when our sun becomes a red giant and consumes the earth. ‘Till then, we can probably keep ahead of sea levels rising at 2-3 mm/year for much less cost than “controlling climate”.
What they have forgotten is that:

As long as the earth endures,
seedtime and harvest,
cold and heat,
summer and winter,
day and night
will never cease.” Genesis 8:22

Relax, enjoy, and lets work on really serious issues like providing alternative fuels to accommodate the rapid decline in global oil exports after peak oil.

RunFromMadness

This paper does not include the phrase “an area roughly the size of Manhattan”. Therefore it is not science.
I’m off to watch Independence Day and The Day After Tomorrow before my house burns down from global warming.

Hank

So much theorizing of the anthropogenic global warming crowd is based on wishful thinking. What wish? The age old wish to be judged from on high. The story of Noah, passover, and apocalyptic doomsday (to name a few) are all inescapable features of our civilization, always on ready to seduce the uneducated and unthinking mind into making grave judgment on one’s fellow man. But this is the simpleminded outlook. The only known place of judgment in the universe is in the mind of humans. So it is naive to attempt blanket condemnation of modern man as so many current environmentalists do. The task of environmentalism will never be so simple. It will always take difficult and honest inquiry. This post on mechanisms of continental glaciers is a great addition to the inquiry.

Daryl M

Ray (09:12:14) :
When you think that a 10 cm thick ice bridge can support a fully loaded 10 wheels truck […]
First off, you don’t state the length and width of the ice bridge, but irrespective, I don’t think anyone in their right mind would drive a loaded truck over a 10 cm thick ice bridge.
By comparision, I understand that the ice road in the Canadian North, which is floating, is typically 3 ft thick.

mondo

Cliff Ollier and Colin Pain are heroes. Simply presenting sound information to confound the alarmists. Well done.

ak

@Slartibartfast The author talks about “deep basins” in which this ice resides. Showing a cross-section of these “deep basins” shows that they really aren’t that deep. The ice isn’t filling in the basin with the basin edge acting as a physical barrier, rather it is sitting atop a very slight (given the scales) depression and the ice can flow over or around the edge easily.
His wording conjured up the idea of a deep bowl filled to the top with ice-cubes versus a plate with the same amount of ice sitting on top, which would be closer to reality.
Just to be clear, IMO, ice flow is far more important to continental glacial movement than basal conditions (except at the very edges of the sheet).