A quick note on thawing ice caps and volcanism

Webcam shot of Eyjafjallajökull erupting on April 17, 2010.

I don't want to get too far into this but there has been a lot of chatter about the link between melting ice caps and increase/decrease/neither of volcanism. The two main articles we're talking about are:

Scientific American, saying that ice loss could increase volcanism:
Ice cap thaw may awaken Icelandic volcanoes

The long and short of the Scientific American study is that you reduce the pressure of rocks in the crust/mantle below Iceland, you generate more melting - depressurization melting of rock. If you melt the ice cap, you release a decent amount of pressure - ice is heavy and adds weight to the crust, so melting ice cap = more melting = more volcanism.

Watts Up with That saying no, it won't:
Reply to: "Ice cap thaw may awaken Icelandic volcanoes"

Now, my take on this is that Scientific American - and the geologists quoted - are not saying that the loss of the ice cap will increase volcanism in Iceland. They suggest that there could be a connection between the loss of ice and volcanism. This has been suggested before for the Cascades after the end of the last ice age from 12-7 k.y. ago. This could be the same for Iceland, where the loss of ice (for whatever reason) might increase overall volcanism ... but is it?

WUWT take on the problem is interesting, saying that the lower pressure will cause the melting point of the rocks to change only a little bit, so you shouldn't expect more volcanism. However, the key to this problem (in my mind) isn't melting point but rather the volatiles dissolved in the magma. Most magmas can dissolve more volatiles (from the source of the magma, not a surface source of water) under high pressure than low pressure. If you release that pressure, then the volatiles escape in the form of bubbles and you can get an explosive eruption (like popping the top of shaken soda can). If you happen to have shallow magma chambers with volatiles near the surface and deglaciate (remove the ice), you might be prompt a reaction of the volatiles (gases) coming out of solution with the magma. Now, if you combine that with even a small amount of additional melting from lower pressures brought by deglaciation, then, maybe you could produce a temporary, larger supply of eruptible magma. Magma does not need external water to produce explosive eruptions (such as an ice cap/glacier) - and it seems that the current eruption is silicic enough to produce its own explosivity due to its viscosity and water content - so the lack of an ice cap should not preclude more explosive eruptions in Iceland.

Now, this is all just speculation on my part and I'm not trying to connect it to global warming, global cooling or the Red Sox subpar start to the season. However, what I can say is that we need to stop trying to look at every study with the lens of climate change - and especially stop treating each side of the issue as adversaries if you don't agree with them. Science is about discussion not confrontation, but a lot of this debate becomes "Jeez, the other guys are idiots because they don't agree with me!" A little civility and open-mindedness goes a long way.

That being said, this idea of deglaciation leading to more volcanism is fascinating and has some evidence that seems to indicate that after a major glaciation, it might happen.

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@George, thanks for the answer to Gina's question. I've been wondering the exact same thing. This is indeed a very long period of high tremor rates, especially low frequency.

Just my (less than) 2 cents....

Is it possible that the current tremor burst is actually the volcano deflating on itself due to lack of pressure? (that is, the magma chamber is exhausted...)

Or is it possible that the volcano has now switched to lava dome extrusion?

By Volcanophile (not verified) on 18 Apr 2010 #permalink

There has been some saying that this eruption is chemical like the eruption in the year 920.

But it looks like that there is something more going on now then in the eruption in 1612 and 1821-1823.

Scientists have stopped saying that the eruption is going to end soon. Now they say that it is currently low, but it might pick up again.

Anyone, is it possible to estimate the position (depth and coordinates) of the source for this harmonic tremor? :)

By Mattias Larsson (not verified) on 18 Apr 2010 #permalink

Hey all, there's a new entry up.

@ Greg, 299

R. de Haan Denial site?? Just like Eugenics, you couldn't question that pseudoscience. Climate Change is also a pseudoscience, I think WUWT is the clearest thinking body in climatology today...

Posted by: Greg | April 18, 2010 6:50 AM

Greg, I agree 100%.

By R. de Haan (not verified) on 18 Apr 2010 #permalink

Go ahead and question climate change. Questioning however involves looking at the evidence, not just listening to talk radio.

Which parts do you consider pseudo science?

A) The measured spectrum of CO2?
B) The increase of CO2 in the air?
C) That we see retreating glaciers and sea ice?
D) That we see warming oceans?

By Larry Foard (not verified) on 18 Apr 2010 #permalink


I don't think anyone is questioning climate change. The climate changes on a regular basis, they are called seasons. The question is man's role in climate change, specifically global warming. The "evidence" as you call it is tainted and biased towards profiteers and globalists who want to make us aerobic earthlings pay for this insanity willingly without any objection or questions at all. Did you simply ignore the leaked emails concerning this or are they are not "evidence" as well? If Al Gore feels a little too warm it is because his head is stuck up somewhere it should'nt be. If you want to join him then by all means do so. Don't force this idiotic idea on people and expect them to but into it. The "scientists" who are involved in this scam need to be prosecuted and any licenses they may have need to be revoked. This crap is along the same line as the health care scam being forced on us. The issue is access to "Health Care," not access to health insurance. One should not cloud these issues with ignorance.

Did you simply ignore the leaked emails concerning this or are they are not "evidence" as well?

The investigation into the stolen e-mails demonstrated that there was no 'there' there. The only people still pushing that story are of a piece with the 9/11 truthers, Obama birthers, and CIA killed Kennedy nutcases.

Do try and keep up, sport.

Already "proven" by Non-government influenced scientists that glaciers are not melting. What you are seeing are several years of very cold weather to cause snow falling on the glaciers to freeze and build up over time. since we are seeing a "normal" climate now, the ice "frozen snow" is melting. The result may well cause the volcanic conditions you describe but not global warming. After all, since the earth has cooled about half a degree in the past twenty years, I don't think we will catch fire in the next few hours. Get a grip and do the science instead of just believing every word you hear because some famous person says it's so. THINK!!!!!!

By Cliff Wood (not verified) on 20 Jun 2010 #permalink