Currently almost all of the world's CO2 removal occurs through natural processes. That's primarily plants and trees taking in CO2 from the air, and the soil absorbing and storing it.But there are limits to how much nature can do. For example, how much more of the world can realistically be given over to forests? Some optimistic scenarios suggest that natural CO2 removal could be doubled by 2050, but that's still only about 4 billion tonnes of CO2 a year.
