Guest essay by Eric Worrall
The Australian ABC has published details of a new climate scare – the possibility that global warming will lubricate the worlds glaciers with meltwater, causing them to speed up, accelerating abrasive erosion.
According to the ABC;
Climate change may cause ‘substantial increase’ in erosion as glaciers speed up
Faster-moving glaciers carve away more of the landscape than their slower-moving counterparts, according to a new study of a New Zealand glacier.
The findings, reported in the journal Science, have significant implications for glacial erosion as Earth gets warmer due to climate change.
“The glaciers will accelerate and the rate of glacial erosion will increase substantially,” said one of the study’s authors, Dr Simon Cox of the Institute of Geological and Nuclear Survey Science in Dunedin, New Zealand.
“So we end up with more rapid carving of our landscape by glaciers and a corresponding increase in the levels of sediment and mud that are carried out in alpine streams and rivers towards the sea.”
Dr Cox and his colleagues spent five months in 2013 and 2014 studying the Franz Josef Glacier in New Zealand’s Southern Alps.
The authors found erosion to be highly sensitive to small variations in the slope of the glacier, the hardness of the rocks over which the glacier is moving, and the amount of rain the region receives.
Read more: http://www.abc.net.au/news/2015-10-09/fast-moving-glaciers-cause-more-erosion/6837954
The abstract of the study;
Assessing the impact of glaciation on Earth’s surface requires understanding glacial erosion processes. Developing erosion theories is challenging because of the complex nature of the erosion processes and the difficulty of examining the ice/bedrock interface of contemporary glaciers. We demonstrate that the glacial erosion rate is proportional to the ice-sliding velocity squared, by quantifying spatial variations in ice-sliding velocity and the erosion rate of a fast-flowing Alpine glacier. The nonlinear behavior implies a high erosion sensitivity to small variations in topographic slope and precipitation. A nonlinear rate law suggests that abrasion may dominate over other erosion processes in fast-flowing glaciers. It may also explain the wide range of observed glacial erosion rates and, in part, the impact of glaciation on mountainous landscapes during the past few million years.
Read more: http://www.sciencemag.org/content/350/6257/193
So how bad is this erosion?
… We designed this study to specifically constrain how glacial erosion relates to ice-sliding velocity. We simultaneously quantified erosion rates and sliding velocity during a 5-month period, from November 2013 to April 2014, over the entire Franz Josef Glacier, New Zealand. This glacier exhibits surface velocities that are largely dominated by high sliding velocities on the bedrock (22), up to about 3 m/day. We measured these high velocities accurately from remote sensing and expected to find large erosion rates. The analysis of continuous suspended sediment load indicated very high erosion rates (about 10 mm/year), whereas glacial sediment production remained lower than the transport capacity of the glacial system (23). We also found that the glacial sediments come predominantly from under the glacier, based on the mineralogy, fossil organic carbon, and the very low fraction of modern organic carbon found in the glacial stream (23). These observations imply that sediments collected at the glacier front can be used to constrain the glacial erosion law. …
Read more: http://www.sciencemag.org/content/350/6257/193.full
Even if erosion does accelerate, I suspect we’ll have enough time to prepare, for the consequences of erosion rates of 10mm / year, in mostly uninhabited, inhospitable regions of the world.
The valley in which the glacier under discussion is situated is located on a Plate Tectonic Boundary. The whole area (Southern Alps near Mt Cook) is being uplifted at 5 to 10 mm/yr. So basal erosion is roughly equivalent to uplift and the bedrock altitude is probably close to a steady state.
This glacier is also subject to dramatic phases of advance and retreat which relate primarily to changes in precipitation. Advance/retreat lag precipitation by only about 3 to 5 years because the ice flow is so fast (relatively short and steep catchment). Here precipitation is strongly influenced by ENSO events. Strong El Nino events tend to be followed fairly quickly by significant ice advances.
Coming soon, SharkGlacier, another made-for-television disaster film.
You mean…YES?…that glaciers will be…YES?…less than…OMG…glacial.
And what about the invasion of snails that move at more than a snail’s pace?
OMG – Something’s going on outside…arghhh…what did that?
Our nation and our world is facing an economic and environmental crisis of disasterous proportions.
Prepare to be…startled:
Glaciers melt from below, from contact with geothermal sources, not from the air.
Where is melting most likely to occur, where the ground is 50 F 50 feet below the glacier or from the air where it’s -20 F 10 months of the year?
If they are being lubricated with water, then by definition, there will be less friction.
Less friction means less erosion not more.
Perhaps, I should disconnect the water hose from my concrete saw to make it cut better.
With sufficiently increased friction, movement will cease and so will erosion.
Rivers are notably full of water and are responsible for a lot of erosion.
Alpine glaciers are rivers with a large amount of their contents in the solid phase.
There is nothing wrong with advancing and retreating Franz Josef glacier (Or any other glacier in the NZ Southern Alps having been there to see them). But the study is complete tosh to be applied more wide spread than just a single glacier. But the ABC will have done it’s work in propagating the propaganda.
…after all, we know we have global warming from a single tree ring somewhere in Russia.
Very good. I hadn’t though of it that way.
And all men are a**holes because one woman got stood up one night in 1998. /snarc
If the glacial rates are non-linear, then from a geophysical and exploration geological perspective, ‘all bets are off’. And accelerating glacial flow actually means accelerated ice production at the glacier headwaters (or should that be headicers?).
As I understand it, most ‘permanent’ thick ice as occurs on Antarctica and Greenland is so heavy that it has depressed the land mass on which it sits, forming basins to depths well below sea level. ‘Lubricated’ ice would have to flow up hill. Besides, ice masses do not advance by physical flow over a land surface but by molecular creep.
Ahh, YOU are understanding some things here.
Flowing uphill was invented by Louis Agassiz to explain the erratic boulders on top of the Jura Mountains in western Switzerland. The Rhone Glacier valley T’s into the wide valley to the SE of the Juras, and Agassiz explains the erratic boulders by having the Rhone glacier flow all the way across the wide valley and push boulders UP the far side – the SE slope of the Juras.
While this unique geography might – MIGHT – correctly explain those particular erratic boulders, geologists and glaciologists have extrapolated Agassiz’s Jura special situation to declare that ice can flow uphill everywhere – and even when there is no glacial “push” possible.
Also, yes, it is plastic flow within glaciers by which they flow. The interface with the underlying ground is actually where the plastic flow is least. The top surface of glaciers flows fastest. This is why crevasses form – the top surface flows faster than the next lower layer upon which it rests – stretching the near-surface ice until it cracks. The term “layer” here I use loosely, since plastic flow is a laminar flow and there are THOUSANDS of such shear layers within the ice.
Also, YES, the interior ice sheet in Greenland is in a basin. And there are very few outlets to the coast, for that ice sheet.
Thus, there are two entirely different zones of ice in Greenland – 1.) the interior ice sheet, and 2.) the coastal slopes. So, when discussing Greenland ice, it is necessary to spell out which ice is being discussed. The coastal zone is glaciers. The interior is a contained ice sheet, contained by a ring of mountains. The ice in the two zones act differently because of the effect the terrain has on how the ice can flow (or not).
The Franz Josef Glacier is on the Wets Coast of the
South Island of NZ. That is not a mis-spelling. It’s the
name we locals give the southern part of the West Coast
from about Hokitika (average rainfall about 10 inches
per month) south. The precipitation there sometimes
has to to be seen to be believed.
The Southern Alps are fold mountains pushed up by
the collision between the Pacific Plate and the Australian
Plate. The Australian Plate there is overriding the Pacific
Plate. The main fault line runs down those mountains
some hundred kikometers plus or minus a few inland
from the West Coast. Of course there are also hotpools
near the glacier as advertised in this
tourist brochure.
To advance at 3m per day would require massive annual
snowfalls on its source snowfield which is only about
20sqkms in size. If it ran at that speed without feed pressure
behind it, it would melt pretty quickly
The last time it advanced started in 1984 and it’s been
known to advance at up to 70cm per day. But don’t worry,
you can still out walk it even at 3m per day. It’s been in
retreat again over more recent years.
There’s nothing there for it to threaten except some klimate
“scientist’s” sense of impending disaster.
The process involved is called regelation. A pressure of at least 20 tons per sq. inch is required.Ice immediately melts at that pressure, as the bottom of the glacier contacts the bedrock. on release of the pressure the ice immediately refreezes. The glacier is effectively sliding on a thin film of water. ice skaters
are using the same principle. Melt water from whatever cause will have no effect, except to maybe wash away wornout fine particles of rock, because meltwater cannot access the pressurized joint between the
glacial ice and the bedrock. Scepticism is Good.
Ken, I think you make a point that is just ignored by many, in the calamity over moullins, and other surface melt phenomena.
In order to have liquid water between the ice and the rock, that water layer has to have an internal pressure that is equal to the pressure of the ice that it is supporting.
Actually the water internal pressure would have to exceed the ice pressure because of the effect of surface tension. Well I suppose that would depend on the boundary layer at the water ice interface, and the water rock interface.
The surface melt water running down cracks in the ice to the rock face, is going to have an internal pressure that is close to atmospheric, so there is no way that water can squeeze in between the ice and the rock, to float the ice on a liquid film.
Any water interface pretty much has to be a consequence of pressure melting of the bottom surface of the glacial ice.
Water likes to stay out of narrow spaces, which is why sharkskin like patterns on surfaces are used to reduce the viscous drag of boat surfaces.
A sanded boat hull has less drag, than a polished one.
3M Scientific Anglers, makes a sharkskin fly line, which floats higher and drier by having a grooved pattern which water cannot penetrate into because of the 2t/r excess internal pressure required to support surface tension contraction.
g
Good stuff, sir.
May I inquire what effect this thin film of pressure-induced water has when the bottom is seriously uneven?
And how thin?
Near the front face of the glacier there certainly is not 40,000 psi at the basal ice. Nor near the lateral edges. Complications everywhere.
All of what you say, plus perhaps these of mine, are reasons to dismiss this paper as oversimplification. As always, the devil is in the details.
“The Australian ABC has published details of a new climate scare”
Where is the scare in the ABC article?
It just looks like a straightforward piece of research to me.
Looks like garbage to me. A 5 month study of one glacier (FJ) during a New Zealand spring/summer is indicative of what exactly? Here’s a little factoid you won’t know about this glacier Harry. At some elevation, I don’t recall how far up from the valley floor, there is a lookout, good spot to take pictures of the glacier pouring over the rock face opposite, and right next to it on the ground is a small pool, with a small stream leading down the road to the valley floor. Put your hand in the pool, from memory I would say the water was a comfortable 45c. So, these “researchers” ignored possibly the primary reason glaciers all over the southern alps change and that is geological activity on a very active fault system with pools of warm water rising above the valley floor.
Patrick.
So you are saying the rate of volcanism is increasing, and this is explanation for glacial retreat. Perhaps you can publish a study?
Why point is there is nothing alarming in the study I can see. It is interesting if the researchers have a hypothesis about erosion rates. Considering global warming is causing a lot of glaciers to move faster, I can see why the Australian ABC is interested in it.
Can you point to where I say the changes are due to volcanism. Ah, thought as much…you can’t. If you can’t correctly quote anything I have said you’re not worth responding to again.
“We would like to track back in time to see how erosion has evolved over the last 12,000 years or so, since we had our last real warming up of the climate…”
Seriously? These nincompoops are comparing today’s small warmup since the LIA, which isn’t even on a par with the MWP with our coming out of the 1,000-year ice age known as the Younger Dryas?
They have the audacity to call themselves scientists?
Melting glaciers are largely the result of the end of the last ice age. Has the climate changed since then? I would suggest not.
Meh. Canada is covered in glacier till. Didn’t hurt us anyway.
Keep the insane predictions coming, believers!
So if glaciers recede, it’s proof of global warming. If glaciers advance, it’s proof of global warming. I get it now 🙂
It is utterly amazing how many times scientists will mentally simplify a process in order to get the answers they want.
If you google “plastic flow glacier movement ” like I did, you will find all sorts of DRAWINGS of glaciers moving downhill, and pretty much all of the m that show water at the base show the entire weight of the glacier floating on the VERY thin layer of water – as if the water is spread out evenly under the ice and the ice never once pushes down through that thin water layer to solid ground.
BALDERDASH!.
The water will only exist down there in relatively small locations where there are voids in the basal ice. 90-99% of the ice will be in solid contact with the ground surface. IOW almost all the ice is still touching the ground, not floating on top. The glacier ice will push down and squeeze the (more fluid) water OUT from under it and into cracks and such where the load is less. Remember that 8/9ths of icebergs are under the surface of the water at sea. The weight of the ice pushes the water aside until a weight-density equilibrium is reached. This is also true of glacial ice – 8/9ths of it will try to be below the surface of the water.
The only case in which ALL the ice floats on top is in some lab experiment where the bottom surface of the ice is flat, to match the flat bottom of the water container. And then you are talking about icebergs, not glaciers on rough, uneven slopes. (Then add in the churning of the ice, in its plastic flow…)
This oversimplification is a cartoonish idea that should be thrown out with the bathwater.
Since this is all in the erosive bottom of the glacial valley, what DIFFERENCE does it make to anything or anyone? Plants don’t seem to take hold in glacial till. Darn near every glacial moraine I’ve ever seen photos of has no vegetation it. It is all just heaps of rubble. And the valley UNDER the glacier means nothing to anyone. It’s not like there is a National Forest growing underneath the damned thing
IN ADDITION, let’s follow THAT line of reasoning…
The greens complain when glaciers recede, and they complain when glaciers advance.
What we have here is a bunch of people who will grasp at any straw to yell and scream that the world is changing and THAT IT IS ALL MAN’S FAULT. They hate humans, period. WHO THE HECK CARES WHAT THEY THINK?
I was once an ABC fan and friend of the ABC. No longer. The ABC has has lost all credibility on both scientific and political fronts. It is becoming an irrelevance.