Tuesday, January 02, 2007

Climate Affects Volcanoes, Volcanoes Affect Climate...

We know that volcanic eruptions can change the climate. The ash they throw up into the atmosphere blocks sunlight, cooling Earth. (The 1815 eruption of Mount Tambora in Indonesia caused the "Year Without a Summer" in Europe and North America -- and led to the writing of Frankenstein.) But can climate affect volcanic activity? Several discoveries reported in 2006 say yes.

The first discovery concerns isostatic rebound after glaciation. The rock continents are made of is less dense than the molten rock of the mantle, so continents float on the mantle like a rubber duck floats in your bathtub. Push down on the rubber duckie, or put an ice sheet on top of the continent, and they sink a little bit. When the ice sheet melts, the continent slowly rebounds to its former height. Patrick Wu of the University of Calgary have found links between isostatic rebound and seismic activity. Wu's research indicates that melting ice makes earthquakes, and maybe even volcanic eruptions, more likely as the crust rises to its new equilibrium height.

The work of Allen Glazner, of the University of North Carolina, is even more dramatic, finding a possible link between the dry climate of interglacial periods and supervolcanoes. Essentially, rainfall and groundwater can cool a volcano's magma chamber, making it less likely to build up the amounts of magma needed for a supereruption.

Let's look at this a bit more closely. Interglacial periods are warm and dry, which, according to this new work, makes volcano eruptions more likely. Volcanoes produce both suspended particles, which cool the Earth, and carbon dioxide, which warms it. Depending on which effect is more important in the long run, we may have a climate-stabilizing or destabilizing feedback loop. Either way, the connections are intricate and interesting. I look forward to learning more about this topic.


Ed Davies said...

Volcanoes produce both suspended particles, which cool the Earth, and carbon dioxide, which cools it.

Oops, I think you mean "warms" at the end of that sentence.

Interesting post, though. We really don't know enough about how our planet ticks, do we?

Jane Shevtsov said...

Oops, brain fart! Fixed it.