Lots to unpack here. First, consider the delta in PPM between present day and pre-industrialization [1]. Next, consider that the ocean has acted as a carbon sink [2] (you mention this), but to great detriment to its chemical composition (more CO2 = increased acidity). We should absolutely not rely on it further as a carbon sink if we expect to use the ocean for aquaculture and to sustain life. Finally, soil, plants, and trees are in no way able to absorb CO2 at the rate necessary to mitigate climate change. This leaves air source extraction as a critical need. I'm partial to Climeworks [3], but any technology that can sequester CO2 underground in a stable form will do.
I specifically wrote that we need further work on ocean deacification, because of all those things you've mentioned.
It's not an either/or proposition: we need to do all of these things:
- restore the ecosystem's ability to consume CO2
- decrease our production of CO2
- develop technology to artificially sequester and consume CO2
Alongside other, non-CO2 related things like restoring biodiversity and ecosystems (where possible, mass extinction is still a thing), reducing our chemical output and destruction of nature etc.
[1] https://www.climate.gov/news-features/understanding-climate/...
[2] https://www.ipcc.ch/site/assets/uploads/2018/03/srccs_chapte...
[3] https://climeworks.com/