March 14, 2011

Volcanism Caused by Global Warming?

Filed under: Volcanism

We all know that if you are impacted by a flood, drought, tornado, hurricane, heat wave, wildfire, tsunami, earthquake, landslide, or anything else you can dream of, you might as well just go ahead and blame global warming—after all, if you don’t someone else most assuredly will. Whether or not you’d be correct, though, is another story entirely.

Over the past year, a number of volcanic events have been in the news from Europe to Hawaii and now the big earthquake in Japan and resultant tsunami has a lot of folks asking “can we blame all of this global warming.” Literally one day after the earthquake in Japan, The Daily Caller ran a story entitled “Some respond to Japan earthquake by pointing to global warming” starting with the sentence “Hours after a massive earthquake rattled Japan, environmental advocates connected the natural disaster to global warming. The president of the European Economic and Social Committee, Staffan Nilsson, issued a statement calling for solidarity in tackling the global warming problem.”

Another a story at Grist was titled “Today’s Tsunami: This is What Climate Change Looks Like” (but this Grist story was softened after severe critcism from the Center for Environmental Journalism). Even in far away places like Nunavut Canada, people are pushing a global warming/earthquake link.

And back when volcanoes were closing down air traffic in Europe, Reuters (April 16, 2010) carried a story worldwide entitled “Ice cap thaw may awaken Icelandic volcanoes”. Here is an excerpt from that story:

A thaw of Iceland’s ice caps in coming decades caused by climate change may trigger more volcanic eruptions by removing a vast weight and freeing magma from deep below ground, scientists said on Friday.

They said there was no sign that the current eruption from below the Eyjafjallajokull glacier that has paralysed flights over northern Europe was linked to global warming. The glacier is too small and light to affect local geology.

“Our work suggests that eventually there will be either somewhat larger eruptions or more frequent eruptions in Iceland in coming decades,” said Freysteinn Sigmundsson, a vulcanologist at the University of Iceland.

“Global warming melts ice and this can influence magmatic systems,” he told Reuters.
The end of the Ice Age 10,000 years ago coincided with a surge in volcanic activity in Iceland, apparently because huge ice caps thinned and the land rose.

“We believe the reduction of ice has not been important in triggering this latest eruption,” he said of Eyjafjallajokull. “The eruption is happening under a relatively small ice cap.”

The door is left wide open here for the alarmists to add volcanic activity to their long list of consequences of burning fossil fuels.

If you search the internet for links between volcanism and climate change, you will find thousands of sites, but most deal with how volcanic activity impacts climate. Big volcanoes dirty-up the stratosphere, less solar radiation makes it to the lower atmosphere and surface, and the earth cools. The volcano/climate link is well-established from both modeling studies and research on the empirical record of climate.

However, this new link with climate change causing volcanism is gaining steam, and news reports and websites on the subject are increasingly common (there is even rumor that the IPCC may include this linkage in an upcoming report).

A major review article on this subject entitled “How will melting of ice affect volcanic hazards in the twenty-first century?” has appeared recently in the prestigious Philosophical Transaction of the Royal Society by Lancaster University’s volcanologist Dr. Hugh Tuffen. He begins the piece noting that “Glaciers and ice sheets on many active volcanoes are rapidly receding. There is compelling evidence that melting of ice during the last deglaciation triggered a dramatic acceleration in volcanic activity. Will melting of ice this century, which is associated with climate change, similarly affect volcanic activity and associated hazards?” Well, we definitely found the correct article.

Tuffen is probably correct that volcanic activity increased during the past deglaciation of the planet, but the deglaciation of the planet was orders of magnitude larger than the melting expected during the 21st century. Losing a mile of ice covering the northeastern United States is a rather bigger geophysical event that losing a small amount of ice over the next century. Although while perhaps it is possible that even relatively small changes in ice cover will instigate volcanic activity, making such a claim disregards the enormous unknowns on this subject. Before any credible prediction can be made (or taken seriously), major uncertainties would have to be reduced.

In his paper, Tuffen identifies six major uncertainties:

Uncertainty about the time scale of volcanic responses to ice unloading. We currently have only limited insight into the reasons for delayed volcanic responses and the time scales involved; response times are likely to differ in different tectonic settings.” [The problem is that ice may indeed be lost from atop volcanic areas, but no one knows the lag time before the volcanoes would respond.]

Poor constraint on how ice bodies on volcanoes will respond to twenty-first century climate change. The highly localized effects of topography, microclimates and local geothermal and eruption-related processes on volcanoes conspire to create considerable diversity in the response of individual glaciers and ice sheets to climate change”. [We agree and we have written essays on how different glaciers and ice sheets might respond to changes in climate. Antarctica is expected to thicken over the century, not thin.]

The sensitivity of volcanoes to small changes in ice thickness or to recession of small glaciers on their flanks is unknown. Although there is strong evidence that wholesale ice removal during deglaciation can significantly accelerate volcanic activity, there is considerable uncertainty about how volcanic responses to unloading scale with the magnitude, rate and distribution of ice unloading.” [Just because volcanoes responded to enormous deglaciation is no guarantee that they will respond to relatively small changes in ice cover.]

Lack of data on how past changes in ice thickness have affected the style of volcanic eruptions and associated hazards. Most statistical studies of the effects of ice thickness changes on volcanism have focused exclusively on the frequency of eruptions. It would be of great interest to know whether the sizes of eruptions or the probability of large caldera-forming events increase during periods of ice recession.”

It is not known how localized ice withdrawal from stratovolcanoes will affect shallow crustal magma storage and eruption. Existing models for how loading by ice affects volcanism have focused on large (greater than 50 km diameter), near-horizontal ice sheets and mantle melting. Stratovolcanoes, which constitute the vast majority of ice- and snow-covered volcanoes worldwide, are entirely different systems, being characterized by smaller, thinner ice bodies and the existence of crustal magma chambers.”

Broader feedbacks between volcanism and climate change remain poorly understood.” [More volcanism could yield more atmospheric CO2 and enhance warming. Debris from eruptions could cover the once near-white ice cover and accelerate melting. More volcanism could also mean more dust in the stratosphere thereby cooling the earth.]

What we see here is what we see throughout the climate change issue. Simple claims are made about how something is linked to global warming, and if it sufficiently scary, it becomes front page news. Look up the issue in the serious scientific literature, and an entirely different picture immediately emerges!

Reference:
Tuffen, H. 2010. How will melting of ice affect volcanic hazards in the twenty-first century? Philosophical Transaction of the Royal Society A, 368, 2535-2558.




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