Phase 2- water vapour condenses, forms oceans. Lots of carbon dioxide removed as it is dissolved in oceans- goes through a series of reactions to form carbon precipitates- form sediments on seabed. Green plants and algae evolved and absorb carbon dioxide so can photosynthesise. Marine animals then evolved. shells and skeletons contain carbonates from oceans. Organisms took in some carbon from atmosphere and oceans, which became locked up in rocks and fossil fuels after organisms died. When plants, plankton and marine animals die, fall into seabed and get buried by layers of sediment. Over millions of years, get compressed and form sedimentary rocks, oil and gas- trap carbon to reduce levels of carbon dioxide. Coal, crude oil and natural gas made by this process- formed fro deposits of plankton- form reservoirs under seabed when they get trapped in rocks.