Earth may hide a lethal carbon cache

Carbon buried in the Earth could ultimately determine the fate of our planet's atmosphere. So concluded a pioneering meeting last week about the Earth's long-neglected "deep" carbon cycle.

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. This realisation could have profound implications for our climate, argues Robert Hazen of the Carnegie Institution, who organised the meeting at the institution's Geophysical Laboratory in Washington DC. "We may be on the verge of a transformational moment... a glimpse ...