Mineral weathering is reasonably predictable in terms of what it will be capable of capturing.

Planting trees is anywhere from very good (cutting the trees down and burying it so deep it doesn't rot back to the atmosphere) to very bad (the tree doesn't grow or burns in a fire, effectively adding CO2 equal to the cost of planting).

Maybe we can plant fields of new coal to be found in a million years ;-)

Apparently we can’t. That worked because there were no bacteria that’d consume the biomass and release CO2 back then.

If its deep enough underground, the conditions favorable to that bacteria may not exist.

I'd disagree with "very bad" being the bottom end of the scale. The cost to plant a tree is not very resource intensive and many trees lost would be made up for a single successful tree. It's almost all upside.

The problem is you haven't actually offset anything, and by the time you find out that you have offset nothing, the carbon you were hoping to sequester is back again.

There's other not good (carbon-wise) uses of trees, like harvesting for firewood, or culling to prevent the spread of diseases like oak wilt or bugs like the emerald ash borer.

Compared to chemically weathering minerals, trees are at best a gamble. Most people aren't stuffing dead ones in really deep holes; the best we can hope for now is they get cut up into quality furniture or building materials that will last decades or more.

There's really very little long-term upside to randomly planting trees and hoping for the best, aside from the fact that trees are really nice things and intrinsically good to have. Just not a super effective carbon sequestration scheme by comparison.

Planting trees isn't a method of carbon capture. Trees die, decay, and release the CO2.

Famously, they also burn.

Famously they also make houses and many other products like paper.

If you plant a forest where there was no forest before, then while individual trees will die, the entire forest will capture carbon dioxide proportional to its biomass.

Forests will typically grow for years-decades, and absorb carbon dioxide throughout, till their biomass (per km^2) reaches an equilibrium point. At that point the forest will go from a carbon sink to carbon neutral (averaged over several years to account for forest fires and subsequent regrowth).

Yes, they emit some carbon when they decay, but not all of vegetation goes back into CO2, so even mature forest is an overall carbon sink. New forest is an even larger carbon sink.

Estimates of the carbon sink per km2 are about ~200-400 Ton/km2/yr or ~2-4 Ton/ha/yr (Slope of curves in Fig 7 in https://www.nature.com/articles/s41598-021-99395-6) To absorb our current 10 GTon C (~30 GTon CO2) we would need ~30-50 M km2 of area; Arable (crop) land area is ~15 M km2 (~10% of Earth's total land area) and grassland is ~30 M km2. Clearly we aren't going to turn nearly all of arable/grass land area to forests, but vegetation management could be a significant part of carbon management.