Earth’s natural long-term carbon cycle removes carbon dioxide (CO2) from the atmosphere through a chemical reaction between volcanic rock, CO2, and water.
The process, which normally takes millions of years, involves rain interacting with CO2 and breaking down rocks, which are then transported by rivers into the ocean for use in shells and corals.
Without this carbonate-silicate cycle of water interacting with volcanic rocks to remove CO2 from the atmosphere, Earth would look like Venus.
The long-term carbonate silicate cycle has lead to 99.9% of all carbon on earth being stored in solid form as rock, in sediment, limestone (CaCO3), or dolomite.
The amount of carbon in the atmosphere as CO2 is only .00095% of the total carbon on Earth. Our climate change problems are being caused by an approximate 1/3 increase in this amount of CO2.
Total global CO2 emissions are now 100 times more than the amount of CO2 the carbon cycle typically converts into carbonate rocks.
Most of the weatherable rocks on Earth that are exposed, have already weathered and the reaction has caused a coating to form that slows the reaction.
At certain times in geological history, when tectonic forces have exposed large quantities of volcanic rock in humid, tropical latitudes, it has greatly increased the rate of CO2 removal from the atmosphere.