That is actually the most effective way of scrubbing CO2. The problem is that trees take up a lot of valuable real estate.

Lots of unused land are shrubs, grass and hillsides. The mediterranean coast used to be all trees a little more than two millenia ago[0]. Some semi-arid zones around deserts could also support reforestation.

[0] https://en.wikipedia.org/wiki/Deforestation_during_the_Roman...