By Nick Iraola
Volcanic eruptions are one of the most vivid and awestruck natural phenomena on Earth. Their powerful impact on climate change is clear, as their catastrophic volumes of ash and minerals descend chaos into our atmosphere and alter our climate cycles.
If climate impacts of terrestrial volcanoes are that clear, then why haven’t we been paying more attention to the climactic impacts of underwater volcanoes? Is it possible that we have been missing a significant player in climate change, and that underwater volcanoes could have been the straw that broke the Ice Ages’ back?
A recent paper published in March of 2015 by Dr. Maya Tolstoy of Columbia University took a look into what types of impacts Mid-Ocean Ridge volcanoes had on climate change and what we could have been missing. She claims that undersea volcanoes could be, “…acting as a climatic valve that causes the flow of greenhouse gases to fluctuate.”1 This fluctuation may even have been the catalyst that drove the abrupt end of the ice ages.
If underwater volcanoes are that influential, why has it taken science this long to notice? Tolstoy explains that little has been known about the Mid-Ocean ridge eruptions because, “…most occur far from land, at seismicity levels below the detection capabilities of global seismic networks.”
The current understanding is that underwater volcanoes erupt at a fairly constant rate, emitting small amounts of CO2 over a cycle of about 100,000 years. These emission amounts are significant, but not enough to raise any alarms about impacting climate due to their occurrence over a long time scale.
With newly available technology in seafloor hydroacoustics, Tolstoy argues that our current understanding is a misconception. She boasts that underwater volcanoes are moderately dormant over this 100,000-year time scale, and actually erupt in short, consecutive pulses during ideal conditions. This releases carbon dioxide in a condensed time span versus spacing it out over a 100,000-year cycle.
Her theory is supported by data that reveals a direct correlation among CO2 emissions, production of seafloor crust, and high orbital eccentricities. At high orbital eccentricities (when the moon is furthest from the sun) magma in the oceanic crust experiences increased pressure of being forced out of its chamber. When sea level is low during Ice Ages because of glacial formation, this pressure exceeds the strength of the crust and an eruption occurs. Carbon dioxide is emitted into the ocean, equilibrates with the atmosphere, and increases the greenhouse effect.
So could these volcanoes really have spelled the abrupt end for the Ice Ages? The key in Tolstoy’s study is the pulsing frequency compared to spacing out eruptions over time. Oceanographic scientist, Dr. Iraola of UNC at Wilmington’s Center for Marine Science, comments that: “Underwater volcanic high frequency events over a small time scale would result in rapid increases in atmospheric COs levels, thereby quickly warming the planet, and plausibly ending an Ice Age.”
For now, continued monitoring and data collection is needed to further robust Tolstoy’s theory. One thing is for certain: with the startling results from Tolstoy’s work, we’d be hard-pressed to continue ignoring underwater volcanoes as significant climate change players.