According to a recent study by researchers at the University of Cambridge, we’ve been underestimating the CO2 levels at the end of the last ice age. It turns out that melting glaciers lead to an increase in volcanic activity, something they have known about for a while, but so does increased erosion, a side effect of that melting which they hadn’t thought of before.
Melting glaciers reduce pressure on the Earth’s mantle, allowing for greater magma production and more volcanic eruptions. That’s because rocks under less pressure melt at lower temperatures. Erosion contributes to this as well, as parts of the Earth’s crust change in depth; those regions put less pressure on the mantle.
And of course, increased volcanic activity unleashes more CO2 into the atmosphere, which results in more melting, and so on. It is this system, which brings an end to an ice age, a process that generally lasts about 20,000 years or so. Glacial and interglacial periods (we’re in the latter now) tend to last in 100,000-year cycles.
Because the timescales are so vastly different, the researchers warned readers not to draw too strong a connection between these systems and the glacial melting that were seeing now as side effect of human activity. Global warming is leading to increased glacial melt, and increased erosion, both form those glaciers and in other ways as well.
That could mean that, as time goes by, we will see an increase in volcanic activity around the world, which could have a lot of negative consequences. For one, that means more CO2 in the atmosphere, but it also means the potential for massive destruction and huge loss of life, depending on the activity in question. If the rebuilding effort afterward leads to greener communities moving forward, it may help offset some of the damage, but at what cost?