The oceanic crust is about six miles thick, and floats on top of gigantic convective cells originating over a thousand miles down in the mantle. The movement of these convective cells is what causes plate tectonics and earthquakes like the Japanese quake last month. Relative to the size of the sphere it sits on, the crust is thinner than an apple skin.
By some amazing new climate science principle, an increase of 0.0001 atmospheric CO2 concentration over the crust is affecting the speed of convection in the mantle thousands of miles below it.
(And they wonder why we think that climate science is the chosen profession among morons.)