It's not just ships. Before and after ships forests were/are cleared for farming. Net carbon sequestration of almost any forest is likely to be better than cropland and pasture - more so the old forests with well developed fungi and worms and stuff that fix and recycle some of it, not so much the timber forestry but i sustect theyre better than farms still.

Steel ships did not really even slow deforestation much - globally. Though you could argue that the sail ships enabled Europeans to bring all their various shit to the Americas - so it is maybe linked to the farming thing.

https://ourworldindata.org/world-lost-one-third-forests . FYI This graph is a bit misleading because time is warped on the vertical.

We also drained and dried out wetlands and bogs which are quite good at trapping a high amount of rotting material, also to make farmland. I'm not sure if that is counted in those stats - that is possibly more of a European overpopulation thing than a global one anyway.

I dont see how it will stop unles people start eating less, or more efficiently (I guess swap a lot of cow for cereals).

I don't think monocultures + fertilizer + pesticides is going to be all that sustainable at keeping high yields in the long run - but we shall see about that I guess. Gene techlogy does seem to create some advances.

Decomp still sequesters carbon... where do you think all the oil came from, to begin with?