[kiliantics]

How are you arriving at the 12 trillion trees number? I think there are some less obvious ways that trees can capture more carbon. For instance, trees build soil over time. Much of the deforested land in the world has had its topsoil washed away without trees to hold it in place. That soil is also a form of captured carbon.

[jjk166]

Earth currently has about 3 trillion trees, this population captures about 20% of current human co2 emissions (which includes soil creation). To get to 100%, you need 5 times as many trees, which means increasing the current population by 12 trillion.

Of course this is a crude estimate, not all trees are equal and planting trees in such large numbers would undoubtedly have other effects, but no matter what you are talking about an absurdly large number.

[stevage]

Soil carbon sequestration is definitely well known.

Eg https://carbonfarmersofaustralia.com.au/carbon-farming/soil-...