The Oceans and terrestrial biomas. This reaction takes up CO 2 . The CO 2 is taken up in the upper waters very quickly just a few years. But the oceans can only hold a small amount of the CO 2 that we are producing. The deep oceans could hold much more.
Diffusion is very slow.
On theorder of thousands of years. One way to get it down there is the biological pump. This is where organisms die and fall through the thermocline into the deep ocean. But the growth rate is not limited by CO 2 . Plants grow faster when CO 2 is higher.