From the Institute of Physics , something so overreaching I just can’t believe the Institute of Physics would put out a press release on it. Where does one start with stuff like this? This is all modeling, they haven’t even tested any actual sea ice to see if it follows the theory. Their premise would be easy to test with some glacier water, a freezer, a controlled gaseous CO2 source, and a tensile/ductile strength mechanical force tester for brittleness. But that sort of basic testing wasn’t done. Yet, they equate their modeled posited effect to be the cause of the Pine Island Glacier breakoff, as if somehow events like that never happened before CO2 was at 392PPM. Note the abstract and link to the paper below. – Anthony
The well-documented presence of excessive levels of carbon dioxide (CO2) in our atmosphere is causing global temperatures to rise and glaciers and ice caps to melt.
New research, published today, 11 October, in IOP Publishing’s Journal of Physics D: Applied Physics, has shown that CO2 molecules may be having a more direct impact on the ice that covers our planet.
Researchers from the Massachusetts Institute for Technology have shown that the material strength and fracture toughness of ice are decreased significantly under increasing concentrations of CO2 molecules, making ice caps and glaciers more vulnerable to cracking and splitting into pieces, as was seen recently when a huge crack in the Pine Island Glacier in Antarctica spawned a glacier the size of Berlin.
Ice caps and glaciers cover seven per cent of the Earth—more than Europe and North America combined—and are responsible for reflecting 80 per cent of the Sun’s light rays that enter our atmosphere and maintain the Earth’s temperature. They are also a natural carbon sink, capturing a large amount of CO2.
“If ice caps and glaciers were to continue to crack and break into pieces, their surface area that is exposed to air would be significantly increased, which could lead to accelerated melting and much reduced coverage area on the Earth. The consequences of these changes remain to be explored by the experts, but they might contribute to changes of the global climate,” said lead author of the study Professor Markus Buehler.
Buehler, along with his student and co-author of the paper, Zhao Qin, used a series of atomistic-level computer simulations to analyse the dynamics of molecules to investigate the role of CO2 molecules in ice fracturing, and found that CO2 exposure causes ice to break more easily.
Notably, the decreased ice strength is not merely caused by material defects induced by CO2 bubbles, but rather by the fact that the strength of hydrogen bonds—the chemical bonds between water molecules in an ice crystal—is decreased under increasing concentrations of CO2. This is because the added CO2 competes with the water molecules connected in the ice crystal.
It was shown that CO2 molecules first adhere to the crack boundary of ice by forming a bond with the hydrogen atoms and then migrate through the ice in a flipping motion along the crack boundary towards the crack tip.
The CO2 molecules accumulate at the crack tip and constantly attack the water molecules by trying to bond to them. This leaves broken bonds behind and increases the brittleness of the ice on a macroscopic scale.
Carbon dioxide enhances fragility of ice crystals
Zhao Qin and Markus J Buehler 2012 J. Phys. D: Appl. Phys. 45 445302 doi:10.1088/0022-3727/45/44/445302
Abstract:
Ice caps and glaciers cover 7% of the Earth, greater than the land area of Europe and North America combined, and play an important role in global climate. The small-scale failure mechanisms of ice fracture, however, remain largely elusive. In particular, little understanding exists about how the presence and concentration of carbon dioxide molecules, a significant component in the atmosphere, affects the propensity of ice to fracture. Here we use atomic simulations with the first-principles based ReaxFF force field capable of describing the details of chemical reactions at the tip of a crack, applied to investigate the effects of the presence of carbon dioxide molecules on ice fracture. Our result shows that increasing concentrations of carbon dioxide molecules significantly decrease the fracture toughness of the ice crystal, making it more fragile. Using enhanced molecular sampling with metadynamics we reconstruct the free energy landscape in varied chemical microenvironments and find that carbon dioxide molecules affect the bonds between water molecules at the crack tip and decrease their strength by altering the dissociation energy of hydrogen bonds. In the context of glacier dynamics our findings may provide a novel viewpoint that could aid in understanding the breakdown and melting of glaciers, suggesting that the chemical composition of the atmosphere can be critical to mediate the large-scale motion of large volumes of ice.
Introduction
Ice caps and glaciers cover 7% of our planet, greater than the land area of Europe and North America combined [1]. They reflect 80–90% of the solar radiation and trap a large
amount of carbon dioxide. Specifically, the Arctic accounts for 10–15% of the earth’s carbon sink [2]. The glaciers’ dynamical behaviour and stability play important roles in controlling the global climate [3, 4]. Thereby, the facture mechanism of ice is of paramount importance for the understanding of glacial dynamics [5], and at a fundamental level is controlled by how a single crack propagates in ice crystals via the
breaking of chemical bonds [6]. Such growth of cracks eventually mediates the breakdown of ice, as exemplified in recent incidents of large-scale fracture of glaciers [7, 8]. Very
large-scale ice fractures occurred recently close to the Pine Island Glacier in the Antarctic region, which generated an iceberg with an area of around 880 square kilometres, the size
of the city of Berlin [9].
While the macroscopic mechanical properties of pure ice are well understood by laboratory tests and its behaviour has been characterized by existing fracture
mechanics models [10], the effect of environmental conditions such as the concentration of carbon dioxide, have not been incorporated into existing models. Lack of such knowledge prevents us from understanding how changes in the chemical environment affect the stability and movement of glaciers, which is important given the rising levels of carbon dioxide in the atmosphere.
[Suggestion: do some laboratory testing to get the same level of understanding]
…
Conclusion
Using atomic simulations with the ReaxFF reactive force field, we investigated the effect of carbon dioxide on the fracture behaviour of ice. We find that the material strength
and fracture toughness are decreased significantly under increasing concentrations of carbon dioxide molecules. This phenomenon is caused by the interaction between water and carbon dioxide molecules. Carbon dioxide molecules first adhere to the crack boundary by forming hydrogen bonds, and then migrate along the crack boundary towards the crack tip.
The dissociation energy of hydrogen bonds at the crack tip is decreased under the attack by carbon dioxide. This migrationattacking process repeats itself and renders the ice crystal more brittle by mediating crack propagation. Our theoretical model quantitatively accounts for the effect of carbon dioxide on the surface energy and fracture toughness of ice. It could be instrumental for further studies of ice fracture in various chemical environments and may be scaled up by incorporating it into models of glacier dynamics.
paper here (you may need to register for free account to read it)
http://iopscience.iop.org/0022-3727/45/44/445302/pdf/0022-3727_45_44_445302.pdf
Related articles
- S. African Scientist Kelvin Kemm: Glacier melting is not caused by global warning: ‘To melt ice, the temperature has to go up past 0 ºC to at least ‘plus something’ (climatedepot.com)
- Thwaites Glacier Tongue Major Calving Event, Antarctica (glacierchange.wordpress.com)
I have taken a quick look at the paper, as far as I can see what they have done is run a molecular dynamics simulation on a very small and very simplified system, they justify doing it at all by alluding to the real world, and then the press release makes a huge leap which the results of the paper in no way substantiate.
It appears that they have modelled a very small cube of pure ice, 44 Angstroms across and containing only 2880 water molecules. They then introduce a ‘crack’, which actually seems to be a cavity in the middle of the system created by removing some water molecules (they don’t say how many). Into this void they then place CO2 molecules. They describe the ratio of CO2 to water molecules as being the ‘concentration’ of CO2, which varies from 0.2 to 2 percent (ie. 6 to 58 CO2 molecules?). My first problem is that this is not really a concentration at all, just a ratio of molecules in the system partitioned into two phases – does this reflect the distribution of CO2 in glacial ice? Secondly there appears to be nothing else in the system, no air, no liquid water, no salts, no lattice defects – again, is this the best representation of reality? This kind of excercise can be legitimate, but on the physical scale of this kind of simulation it is only ever possible to model limited aspects of a real system – for instance, real glacial ice must be full of dirt (significantly affecting its bulk mechanical properties), but the tiniest visible speck of dust would be massively larger than the whole system modelled here!
The next part of the simulation is to simulate a mechanical load and measure the fracture toughness of the system at various CO2 ‘concentrations’. The results presented (Fig.3) show the modelled toughness with no CO2 is 19.4kPa m^1/2 compared to an experimetal value of 24.5+/-5.3kPa m^1/2. At 0.2% CO2 (2000ppm) there is virtually no difference, about 18kPa m^1/2 – well within experimental variation. At 0.5% CO2 (5000ppm) there is a significant reduction to about 14kPa m^1/2. These are fairly massive CO2 concentrations (and the local concentration is really much higher than the average across the system suggests), although the authors do suggest that there are measured values that justify them.
I would say that they have observed a mechanism in a model whereby CO2 may promote the propogation of cracks in ice, this can be considered a hypothesis rather than an experimental result (modellers can be rather bad at confusing the terminology) and would require experimental substantiation – which I think would be rather difficult (proving the mechanism, not testing the effect of CO2 on the mechanical properties of ice). The two main flaws in the logic of the press release as I see it are in extrapolating this extremely limited system to a glacier, which is a much more complex system; and that the results shown have any significance at all to a world where atmosperic CO2 concentrations have risen from 280 to 390ppm.
Maybe my reference to Alain Sokal could have been clearer:
“Sokal is best known for the Sokal Affair, in which he submitted a deliberately absurd article[1] to Social Text, a critical theory journal, and was able to get it published.” (Wikipedia)
This paper could be in the same category.
see google for right answer: Climate change: The untold MUST READ truth behind the making”
or:”Defense for Dr. Charles Bolden: empirical evidence that climate change is human CO2″
THESE ARTICLES FOR DESSIMINATION. JSALDEA12
This paper has a serious intellectual flaw. Because glacial ice is near its melting point, it flows by creep: the movement of defects in the crystal structure. Another mechanism is grain boundary sliding, a strong inverse function of the grain size. Because of this, the build up of stress sufficient to cause cracking is quite difficult.
This paper is in reality about the crack propagation rate for a given normal stress once cracking has started. This may be affected by CO2 competing for hydrogen bonds. However, I strongly suspect these people have forgotten that the concentration of CO2 is set by the partition coefficient between adsorbed and dissolved molecules.
Junk science until they have experimental verification. And because that so easy to do, i am highly suspicious they might have already done it and found the theory didn’t work.
PS I am a materials’ scientist.
@ferdinand meeus Engelbeen says:
October 11, 2012 at 3:51 am
responding to
H.R. says:
October 11, 2012 at 2:40 am
You bring up some very good additional points (thanks!) but I was just thinking only about the difference in the number of CO2 molecules available to react with H2O molecules regardles of other conditions. I looked up the minimum number of H2O molecules to form an ice crystal and it’s probably 275.
http://phys.org/news/2012-09-chemists-smallest-molecules-ice-crystal.html
Now there’s a whole lotta ice crystals in a glacier (multiplied by at least 275 to get H2O molecules) and there are only 390-something ppm CO2 molecules in the atmosphere available to attack all those ice crystals. If the experiment could be done, I could see throwing 1-2 CO2 molecules at a 275-molecule ice crystal and getting a crack to start. But when one scales up to the number of ice crystals in your average, everyday glacier you would tend to come up short on atmospheric CO2 molecules that would even amount to a hill of beans against all those ice crystals.
I realize ‘a whole lotta’ and ‘hill of beans’ are not very precise mathematical terms but my guess is the basic relationship holds; what works on one ice crystal won’t work on a glacier because there isn’t anything close to enough atmospheric CO2 to crack up a glacier.
Just an unsubstantiated opinion from a dumb ol’ engineer, but I think gravity has more to do with glaciers cracking than does CO2.
I was going to raise this question about ice being a major carbon sink, but I see Ferdinand Engelbeen has answered it above. Thank you. I thought the ocean water absorbed a fair amount of CO2, so removing polar ice would expose the arctic ocean surface directly to the atmosphere. Wouldn’t this increase the amount of CO2 absorbed by the ocean?
I just need to pick apart that 80% reflection claim for the sake of my own sanity.
If the albedo of the ice caps is 80% and they cover 7% of the surface area of the earth, then they couldn’t possibly reflect more than 5.6% of the total incoming sunlight. Considering that they will never both be fully illuminated at the same time, that 5.6% figure immediately gets halved to 2.8%. Since the maximum angle of incidence on either pole is ~23.5°, that 2.8% gets multiplied by the sine of 23.5° (0.40) to give 1.1% of total incoming solar radiation that gets reflected by the ice caps.
Clearly, arithmetic and trigonometry aren’t prerequisites to the classes at MIT.
To be picked up by the media and dangerously idiotic politicians as truth in 5….4….3…..2….
I despair that in a world where there are serious problems for probably the majority of the population, that money is spent on such a facile proposition.
Did I miss the bit where they went out and checked the model with Nature? What used to be call ‘experimental observation’?
/sarc
As if this is claim is not ridiculous enough now we have the larest garbage from AP extremist reporter Seth Borenstein claiming that “experts” say global warming is causing increased Antarctica sea ice. After decades of climate alarmists pushing false claims of global warming causing decreased Antarctica sea ice they now switch gears and claim the exact opposite because their prior claims could not stand up to empirical data showing they didn’t know what they were talking about. What a complete farce!
I feel sick.
@jim Turner says:
October 11, 2012 at 5:03 am
I think your post was in queue while I was writing my reply to Ferdinand Englebeen. You said it a lot better than I did. If I had seen your comment, I could of saved myself a whole lotta keystrokes. Nicely done, sir.
I this were true, CO2 would accummulate in the cracks anyway whether 250ppm or 350ppm. A test: take samples of the ice on either side of the crack and into the main body of the ice and compare. Also, initiate a crack in a plaque of ice in a lab vessel, pump varying amounts of CO2 into the vessel, Cool the vessel down and see if it freezes over in comparison to a comparative test with no CO2 added. Shish, that you even need a crack to start with is a confounding issue. The crack got there because of stresses in the ice and progression of the crack is to be expected, especialy if it is at the hinge of a tongue of ice coming from land into the sea. Are we going to use models now exclusively instead of real experiment – if so we can replace physicists with robots.
There are white papers, grey papers, and now puke green papers. HOWEVER! If CO2 proves capable of keeping my drink at the slushy stage, time and money well spent.
This just in from the Chicken Little Institute: CO2 stole my lunch money.
Oh no, the sky is falling!
“…and then migrate through the ice in a flipping motion along the crack boundary towards the crack tip.”
I’m sorry, but I keep getting this vision of the poor CO2s screaming their little heads off as they tumble end over end down the face of the ice wall.
This should be easy to prove; their hapless little bodies will be piled in vast heaps along a line at the bottom of ancient fissures, still clinging to the hydrogen atoms they grabbed futilely on their way down.
Back in the early 1940s, long before CO2 was turned into a criminal molecule, the chemist Primo Levi wrote a little tale called “Story of a Carbon Atom,” while he was detained at Auschwitz.. There is a paragraph in that story where he makes a few observations about CO2, in very different terms than what we are used to today:
http://www.transitionnetwork.org/sites/default/files/CarbonStoryByPrimoLevi.pdf
“[…] But there is more and worse, to our shame and that of our art. Carbon dioxide, that is, the aerial form of the carbon of which we have up till now spoken: this gas which constitutes the raw material of life, the permanent store upon which all that grows draws, and the ultimate destiny of all flesh, is not one of the principal components of air but rather a ridiculous remnant, an ‘impurity’, thirty times less abundant than argon, which nobody even notices. The air contains 0.03 percent; if Italy was air, the only Italians fit to build life would be, for example, the fifteen thousand inhabitants of Milazzo in the province of Messina. This, on the human scale, is ironic acrobatics, a juggler’s trick, an incomprehensible display of omnipotence-arrogance, since from this ever renewed ‘impurity’ of the air we come, we animals and we plants, and we the human species, with our four billion discordant opinions, our milleniums of history, our wars and shames, nobility and pride.”
Larry Hamlin says:
October 11, 2012 at 6:23 am
As if this is claim is not ridiculous enough now we have the larest garbage from AP extremist reporter Seth Borenstein claiming that “experts” say global warming is causing increased Antarctica sea ice. After decades of climate alarmists pushing false claims of global warming causing decreased Antarctica sea ice they now switch gears and claim the exact opposite because their prior claims could not stand up to empirical data showing they didn’t know what they were talking about. What a complete farce!
And that should stop them doing so because???? It never stopped them before, but they really, really do think that they have caused sufficent “dumbing down” that we are that stupid to fall for it, without noticing one or two almighty clangers in their argument! 😉
Alert Alert Alert!, there is a crack in my driveway also. The real alarm should be over the cracking breaking up of science institutions in thje new dark ages of alarmism and bias indulgences paid out.
The well-documented presence of excessive levels of carbon dioxide (CO2) in our atmosphere is causing climate scientists to crack up!
MIT! Are these the same guys from the photo where they can be seen standing beside a colorful climate tombola wheel?
Glaciers are rivers of ice. The amount that calves is based on the flow of that river. If the ice cracks a little quicker at the outflow point that will have very little effect on the rate of flow. The rate of flow is based on the weight of the ice along the river and the incline. Hence, no more ice will be lost into the sea independent of this claimed effect.
They’re taking the piss aren’t they?
So much rot in one paper. 7% ice cover reflects 80% sunlight ? ( they know what they mean but this phrasing is misleading)
CO2 a significant atmospheric component. Hard to see a 0.04% of anything as significant.
Fracturing increases the surface area leading to more rapid melting. Well yes, if you want to be pedantic but if something the size of Manhattan ( the standard measure I understand ) breaks in half the couple of metres of side exposed isn’t a significant increase in area, particularly the bit underwater which is where most of the melting happens anyway.
And so on and so forth. We must be afraid of Carbon Dioxide at all times. You could almost think the whole thing was political if you didn’t know any better.
@ur momisugly Geoff Sherrington
Both authors are from the MIT Department of Civil and Environmental Engineering. There is a list of the students on their website (surprise!). Assuming that “very foreign” names correspond to foreigners, about 23% of grad students are Chinese, 10% are Arabic, and 2% are Indians. This is better than other schools where 60% – 75% of grad students are foreign. For example, the MIT Mechanical Engineering Department has seemingly following distribution of Post-Docs: 37% Chinese, 9% Arabic, and 9% Indians. Educating foreign students is a fantastic idea; however, practically all foreign grad students in Sciences and Engineering and a large fraction of the undergrads receive funding from the US funding agencies covering 100% of their tuition and living expenses. So, the foreign contingent is educated for free at taxpayer’s expense while children of these taxpayers have to pay in full.