Guest post by Steven Goddard
Scientific American has reported that global warming may cause an increase in volcanic eruptions, due to increased magma formation at lower pressures as glaciers melt.
This caught my attention because I used to work as a volcano researcher and igneous petrologist.
That report said that about 10 percent of Iceland’s biggest ice cap, Vatnajokull, has melted since 1890 and the land nearby was rising about 25 millimetres (0.98 inch) a year, bringing shifts in geological stresses.
They estimated that the thaw had led to the formation of 1.4 cubic km (0.3 cubic mile) of magma deep below ground over the past century.
At high pressures such as under an ice cap, they reckon that rocks cannot expand to turn into liquid magma even if they are hot enough. “As the ice melts the rock can melt because the pressure decreases,” she said. Sigmundsson said that monitoring of the Vatnajokull volcano since 2008 suggested that the 2008 estimate for magma generation was “probably a minimum estimate. It can be somewhat larger.”
Interesting theory, but does it work quantitatively? Magmas, as with most solids, do show a direct relationship between the melting point and pressure. As the pressure increases, so does the melting point. (Ice is a noticeable exception to this, and shows an inverse relationship. The reason that people can ice skate is because the pressure under the blade creates a thin later of melted ice which lubricates the surface.
Below is a phase diagram of a basaltic magma similar to that found in Iceland, showing the relationship between temperature and pressure. The melting temperature does decrease at lower pressures. From 100 km depth to 0 km the melting point drops about 300°C. That is about 3°C / km. Ice is about one third as dense as basaltic magma, so the loss of 1 km of ice lowers the melting point by about 1C, or less than 0.1%.
More precisely, this study from the Carnegie Geophysical Institute did an empirical measurement of the relationship for one basaltic mineral – diposide. They found the relationship to be
Tm = 1391.5 + 0.01297 * P
Where Tm is the melting point in degrees C and P is the pressure in atmospheres. One atmosphere pressure is equal to about 10 metres of ice, so one additional metre of ice increases the melting point by about 0.0013°C. The loss of 100 metres of ice would therefore lower the melting point by about one tenth of a degree. The thickest ice in Iceland is only 500 meters thick, so complete loss of all ice would only alter the melting point by about 0.5°C, or less than 0.05%.
The geothermal gradient of the earth is typically about 40°C per km, so a 0.5°C change in temperature is equivalent to a depth change of about 20 metres. Near mid-ocean ridges this gradient is steeper, so the equivalent depth change in Iceland would be less than 20 metres. Is it credible that a 0.5°C decrease in the melting point could stimulate excess volcanic activity? Short answer – no. Volcanic activity is caused by magma rising to the surface, not glaciers melting. However, the loss of the glaciers would reduce the amount of steam and ash generated. Ash is formed when magma is cooled and fractured by steam. So the loss of the glaciers would reduce the size of the steam/ash cloud and make the Iceland volcanoes behave more like Hawaii volcanoes.
In short, the loss of all ice in Iceland would make the volcanoes less destructive.
BTW – On Al Gore’s planet, the geothermal gradient is much higher, with core temperatures averaging millions of degrees.
http://www.youtube.com/watch?v=ag2AWst3Qv4
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Mike Odin (20:17:45) :
The economic damage now being inflicted by the volcano ash upon the British and European economies appears to be on a scale equivalent to the economic damage recently inflicted upon Iceland by the activities of UK and Europe. This is simply a non-judgmental observation unrelated to any karma or other introspection.
An interesting observation Mike. Was karma also responsible for the attempt by some mad Icelandic bankers to destroy West Ham United Football Club?
The Norwegian Prime Minister was stuck in New York because of “The Cloud”. Then he managed to get to Switzerland, and is now in a car on his way to Norway.
They talk a lot, but dont act as if they believe in their own saying.
Why dont they use Video Conference’s. Why all this travelling? The only outcome is [snip], anyway.
Kate: “…The financial crisis in Iceland was brought upon itself mainly by three Icelandic billionaires who all face criminal prosecutions.”
The financial crisis was created using the old “socialist” scam of borrow-to-boom-to-bust except with a new twist: this time the government didn’t do the borrowing themselves.
In the old version, the governments would borrow from international money markets and then spend the money on job creating schemes which would in turn create money in the pockets of those being employed who would spend the money creating more jobs. The big problem being that the wage-inflation caused by this spending made (e.g.) UK goods uncompetitive meaning much a lot of this money went to companies outside of the UK.
And as everyone knows, sooner or later the money has to be repaid, at which point the government must cut back spending, reducing money going into the economy, cutting secondary jobs from those employed on government contracts resulting in a massive and nearly always greater (capital repaid+interest) hit to the economy.
This time, this borrow-to-boom-to-bust “debtoconomic miracle” was accomplished by freeing up personal and business borrowing and instead of government going on a spending spree, the government “covertly” encouraged (i.e. actively stood back and applauded) the massive rise in personal and business borrowing which I think boosted the UK economy by a massive 10% year in year out throughout Labour’s reign of debt.
And what really scares me is the way our political classes debt-addiction means they keep telling us like some sick junkie that all that is needed is “just one more fix” of debt “got to have it to enable them to pull themselves together so that they can sort out their lives/economy”
Doug in Seattle (21:36:41) : shutting down all air traffic over northern Europe seems an over reaction.
The density of the dust cloud is very thin, but jet engines ingest a huge volume of air, and there would be a significant flow of foreign material through the engine.
For the engine compressor, it would be like being sand blasted. Clean, shiny smooth blades are best for efficient compression.
The dust melts at the high temperatures of combustion, and it sticks onto downstream surfaces. This distorts the aerodynamic profiles in the turbine, resulting in further power reduction. The additional mass on the blades would cause vibration.
The engine control systems would shut the engine down as the departure from the normal operating range would be diagnosed as a fault.
If the engine could be forced to keep running, the turbine clearances would eventually be bridged, causing rubbing and lumps to break off, and a cascade of damage flowing down through the turbine. There wouldn’t be much left after that.
Not a good idea to fly with any of the above going on. Better late than dead on time – the authorities did the right thing.
@ur momisugly Kate (23:24:52) :
That’s what happens when the Progressive’s tie the worlds economies together. The idea was to create M.A.D. (Mutually Assured Destruction) through economies instead of weapons. However, someone didn’t really think it through real well (typical for Progressive’s and Greenie’s), as is becoming increasingly apparent.
Al Gored (21:20:21) :
The ash will block out the sunlight if it keeps it up. No summer. Then fresh snow can fall on the ash and effectively bury it. I watched a special where ancient supermassive volcano hunters found what they were looking for in Greenland. Didn’t stop the Ice Cap there.
I’m not going to get worried about the warmists who will grasp at every hypothetical straw, no matter who says what.
We both know that whatever they come up with, they’ll sure as shouting make a total mess of it. People who are prone to panic don’t have a habit of thinking things through prior to jumping on the PA system.
[yes off topic, please use tips and notes ~ ctm]
A long time ago on WUWT where I think the subject involved Geo-engineering and the various “climate scientists” who were advocating all sorts of totally hare brained and potentially catastrophic global climate geo-engineering projects to “stop global warming”, a poster made the comment to the effect that a scientist of his acquaintance had told him, “when you can show me that you can control a volcano then we will sit down and discuss controlling the Earth’s climate!”
I have never forgotten that comment and every time I hear of another significant volcanic eruption I think of that comment and just smile at the hubris and stupidity of those who believe that they have the power to change the global climate and can and will change it to their requirements IF, of course, you give them enough money!
Of course if you ever suggested to these same global climate geo-engineering advocate “scientists” that they first try to exercise control over a small but significant and natural global phenomena such as the current volcanic activity in Iceland which is a quite small item compared to other historic examples of volcanic activity and is a particularly small item when compared to the global climate, they would consider you to be quite mad!
The deficiency in mental capabilities actually resides with the global climate geo-engineering advocates when they can’t even demonstrate ANY ability to modify volcanic activity of any sort and yet claim to be able to geo-engineer the global climate to a set of specifications that they have, in their hubris, judged to be of an absolute necessity for the continuation of human life on this planet.
One cannot write a valid article with these deductions without knowing the properties of the rock between the base of the ice and the top of the magma.
There is no certainty that this mass of rock has any capability to transmit the changes in pressure/thickness from the ice above it to the magama below it.
This rock can be considered as an incompressible load-bearing arch, at one end of a spectum of possibilities, and a spongy material like the matress on a bed that can transmit pressure through its thickness to its base at the other end of possibilities. The authors of the original article are aware of this.
For example, you can remove a brick near the base of a high brick wall without causing significant change. The surrounding bricks do not usually collapse under pressure to fill the void.
There is widespread misunderstanding of the meanings of pressure changes with depth in rock layers. It is not the same as hydrostatic pressure, like water in a well.
The properties of this mass of rock, such as faulting and fracturing, the amount of such, the directions of such, the intrinsic rock hardness, elasticity, amenability to isostasy and other factors determine its behavior. Often these are not known well, because the world’s deepest drill holes seldom go more than 10 km deep. The magma here is modelled at 25 km depth. It is not possible to drill from surface to magma using any known technology, so models have to contain assumptions.
The amount of pseudo scientific [snip] to which we are subjected on an hourly basis makes you very cynical.
No doubt the EU aviatio agency that seems to have been most active in grounding everything has the safety interests of the travelling public most at heart. But I have yet seen a sensible explanation why jetliners can’t fly under the ash cloud. No one expects them to hedge hop. But, despite what is being put about in the media, planes can fly at 5 or 10 thousand feet. OK, they are designed for 30,000 ft and they do use more fuel. But unless I’ve missed something, it would surely be better to have some planes flying lower than just grounding everything?
Couldn’t be anything to do with another EU “beneficial crisis” with a grab for control of aviation in the pipeline, or could it?
And taking the focus off what’s happening in Greece?
Surely not?
Great article, Steven!
To “Just The Facts”: Yes, it’s very disturbing that political leaders seem all to be planning for unverified negative consequences of a possible hotter future, while they appear to ignore the possibility of a sudden planet-wide cold spell. The most important measure would be to stock more cereals again. Currently, there’s quite a surplus of wheat grain (after two good seasons since the food crisis of 2008), so this may be a good time to start.
Scientific American knows tabloid science sells well.
How long before Paris Hilton is linke to Global Warming in Scientific American ?
The pressure of Ice has nothing to do with a volcano surpressing an eruption.
Unlike water pressure. Water pressure is designed to collapse on itself and cover a huge area depending on depth if you desplace water.
Since the boughten theory is that our core is made of nickel, then the mass of nickel must be fire proof from burning and turning to ash with the incredible pressures and heat.
This theory does not stand up.
After 4 billion plus years and we still have pressure build-up which causes earthquakes and volcanoes.
So we wander off into ice-skating …. I think you will find the pressure theory is wrong, and Pearland Aggie post is right. Ice near melting point is just very, very slippery. It’s a surface effect. If you ever tried to pick up a peice of ice that dropped out of your glass onto a hard surface, you would just ….. know that.
>>Not a good idea to fly with any of the above going on.
>>Better late than dead on time – the authorities did the right thing.
It is a matter of density, surely.
In OZ jet aircraft flew through many a dust storm (silicates) without too much problem. That is because they avoided the worst of the dust, but it still abraided the leading edges of the wings.
According to Al Gore, the volcano must be spewing out millions degrees of ash.
@Pearland Aggie (20:51:23) :
Be fair, Steven’s account was the Settled Science for many decades, a universal consensus.
Geoff Sherrington (03:00:43) :
A+ Science!
Espen (03:21:24)
All it takes is a few cool summers to suppress plant growth and we are in deep trouble. Food prices would soar astronomically and collapse the free market system and make currency worthless.
Since scientists are falling from the high positions society has put them in of “All Knowing”. Science itself has made many an error by no one questioning the validity of theories and are they correct.
If I generate a theory, I rip it apart and turn it any way possible to see if it will stand up to the best questioning. I must be doing a hell of a good job as no questions or replies means I must be doing something correctly. On the rare occassion I get a “Very Interesting”.
Jordan (02:05:09) :
That only happens if you are stupid enough to fly through the Cloud itself, which can be easily seen, plus they can fly under or over it.
As Ralph (03:46:41) : surely it is the density that they fly through is the main problem.
Joe (04:11:50),
Very interesting! ☺
“lgl (01:13:44) :
Ah, so that’s why the nearby Katla erupted in 1580, 1612, 1625, 1660, 1721, 1755, 1823, 1860 and 1918.”
The eruptions are primarily due to temerature differentials, as with all eruptions.
A very cool month or so followed by a strong uplift in temperature is what triggers
volcanic activity. Katla eruptions:
http://www.volcano.si.edu/world/volcano.cfm?vnum=1702-03=&volpage=erupt
July 1999, cold June followed by hot July.
Late June 1955, very cool start to June, warms up at and of month.
Oct. 1918, Cool September, turns warmer in October.
May 1860, very cool Feb to April, then very warm May.
Late June 1823, same pattern as 1955.
It is hard to find many exceptions to this pattern of volacano eruptions occurring at a strong temperature uplift after a cold period, in the complete list of VEI 4+
events globally; http://www.volcano.si.edu/world/largeeruptions.cfm
Fears of Katla erupting this June; http://www.newscientist.com/article/dn18690-iceland-waits-for-volcanic-shoe-to-drop.html
are most likely misplaced. My solar based temperature forecast for this May and June is generally above above average, so I do not see any strong temperature differentials occurring through these months.
Fitzy @21:03:09
Latest edition of NGM carries an article on melting Himalayan glaciers. Not referenced so can’t check the source. The description of a “glacier” being ” a deathly shade of black” and “losing mass from the surface down” would indicate soot causing melting rather than increased temperatures. There is a statement that 40% of the glaciers could be gone by 2050. Sounds familiar.
The NGM used to be a great source of information but it has become a mouthpiece for the AGW brigade. Pity.
“The reason that people can ice skate is because the pressure under the blade creates a thin later of melted ice which lubricates the surface.”
Balderdash. The pressure is nowhere near enough to melt the ice. The pressure from an ice skate would change the melting point by a few tenths of a degree at most. Ironically, this is the whole point, albeit with a different sign, that Goddard’s article is trying to make.
http://www.faculty.virginia.edu/lehmannlab/badchemistry.html#ice
Furthermore, why do hockey pucks slide so well on ice? Or curling stones? Why do folks slip over wearing ordinary shoes on an icy sidewalk? The pressure? Give me a break.
Uh oh Main Stream Media just made a big boo boo. A few minutes ago a very animated and seemingly brilliant physics professor (an Asian male – I missed his name) gave a stirring description of how glaciers/ice are making this eruption far more damaging – as in the conclusion above state.
Some ABC Good Morning producer is being called on the carpet right now for screwing up the narrative.
Priceless!
I believe that volcanic eruptions must be due to local accumulations of relatively low density magma that progressively become more buoyant, perhaps from gradual infusion of dissolved subterranean gases, until a point is reached that a surface failure occurs and the dissolved gases leak explosively into the atmosphere.
I suspect that this Icelandic volcanic event has been ‘a long time coming’ and would have occurred sooner or later no matter what had happened to the arctic ice-pack above.