Earth may hide a lethal carbon cache
Carbon is locked away down in the Earth's crust: in magma and old carbonate rocks buried by plate tectonics, in fossil fuels like coal and oil, and in ice lattices beneath the ocean bed. It has long been assumed that this carbon was largely cut off from the surface, and could safely be ignored when analysing the effect of greenhouse gases on climate. Now it seems there may be much more "deep carbon" ready to spew out than we thought.