(Last week’s Calbuco eruption in Chile spews massive cloud of ash and sets off a fireworks display of volcanic lightning. Image source: IFLScience.)
If you look at the geological record of the end of the last ice age, there’s something that crops up that’s more than a little bit disturbing. The approximate 10,000 year period in which 4 degrees Celsius of warming took place was also punctuated by a rash of intense volcanic activity, earthquakes and tsunamis.
It was a time of extraordinary geophysical changes that not only saw the, sometimes catastrophic, melting of massive ice sheets and extreme rises in sea level — it also saw severe geological upheaval. In one region alone — Iceland — instances of volcanic eruption increased 30-50 fold during a period starting about 12,000 years ago. Overall, global spikes in volcanism began near the start of major melt events at around 18,000 years ago and continued on through the Iceland spike at the 12,000 year time-frame, finally tapering off around 7,000 years ago. In the 12,000 to 7,000 year before present period, global volcanic activity was between 2 and 6 times today’s frequency.
(A 2010 study found large spikes in volcanic activity at a number of Iceland volcanoes at the end of the last ice age. Image source: How Will Melting of Ice Affect Volcanic Hazards in the 21st Century?)
Geologically active regions around the world and especially in close proximity to melting ice and rising seas saw much greater volcanic eruption, earthquake and tsunami frequency. In particular, California, Europe, and Iceland saw intense volcanic activity spikes. A set of past events pointing toward 21rst Century risks explored in the book: Waking the Giant — How Climate Change Triggers Earthquakes, Volcanoes and Tsunamis.
A leading theory, presented by Dr. Bill McGuire, Hugh Tuffin, J. Maclennan, Peter Huybers and many others is that changes in stress to the Earth’s crust caused by the loss of billions of tons of mass by ice sheets and the displacement of those billions of tons into the world’s ocean system spurred previously stable magma systems into a chaotic displacement. In addition, direct melting of glaciers on slope systems, rising seas and even changes in flood frequency at individual volcanoes, faults and zones of steep topography can result in heightened rates of eruption, earthquakes and instances of slope collapse.
This evidence is causing scientists to investigate feedbacks between warming and potential increases in volcanic activity, earthquakes and tsunamis. A set of events that may also risk the destabilization of undersea methane hydrate stores through the slope collapse and enhanced magma heating mechanisms as well.
Current Events, Raging Pace of Human Warming Bring old Concerns to Light
Though this line of research isn’t new — with modern studies stretching back to the 1950s and with end ice age upheaval research extending for nearly two centuries — recent events have served to underline old concerns. In 2013, the massive eruptions of Iceland’s volcanoes and related disruption of European air travel brought voices like those of Dr. Bill McGuire again to the fore. And, more recently, the massive Tibetan earthquake of this past weekend, resulting in the loss of 4,000 lives, has called into question current human climate change’s role in geological upheaval events.
(Dust flies through the air during the initial moments of last weekend’s catastrophic Tibet Earthquake. Image source: RT News.)
Evidence from the end of the last Ice Age has already shown that the planet’s uneasy web of seismic faults – cracks in the crust like the one that runs along the Himalayas – are very sensitive to the small pressure changes brought by change in the climate. And a sensitive volcano or seismic faultline is a very dangerous one.
Though the Tibetan earthquake was going to happen at some time, it is possible that changes in ice loading on Himalayan glaciers, changes in water volume outflows in the annual Asian monsoon, and sea level rise adding pressure to the geological plates below coastlines — especially in low-lying Bangladesh — had an impact. Such stresses can increase magma chamber production or trigger fault lines to release.
McGuire notes in Newsweek:
Climate change may play a critical role in triggering certain faults in certain places where they could kill a hell of a lot of people. These stress or strain variations – just the pressure of a handshake in geological terms – are perfectly capable of triggering a quake if that fault is ready to go (emphasis added).
One example of where relatively small changes to geological stress can have a big impact on volcanic activity is the Pavlov volcano in Alaska. As McGuire describes, this volcano only erupts during Autumn and Winter. At that time storms ride up into a nearby ocean zone, pushing an average 10cm or 15cm rise in sea level. The added weight of the water is enough to torque the crust and push magma out. Now imagine the kind of extra volcanic activity that could result from 1, 6, or 250 feet of global sea level rise under the raging rate of human-caused warming and you begin to understand the concern.
So the question that many geologists are asking is this: will the greatly exaggerated spike of human warming and related extreme pace of glacial melt, sea level rise, and rainfall changes also result in a greatly exaggerated spike in volcanism, earthquakes, and tsunami events?
Fault lines around the world will be under increased and ever-changing stress. Volcanoes around the world will see the same. The great Ring of Fire is in an ocean-spanning zone. Many, many volcanic, fault and slope systems encompassed in its arc will feel the added weight of sea level rise caused by human warming. In addition, as much or more than the 4 degrees Celsius worth of warming achieved at the end of the last ice age could be seen by the end of this Century.
It’s that kind of very rapid pace of change that has geologists worried with more than a handful thinking that the catastrophic geophysical changes may have already started.
Hat Tip to Colorado Bob