Not, the removal and the addition don't offset each other - in the sense that someone _else_ emitting some CO2 and you planting a tree don't offset each other.

Not, the removal and the addition don't offset each other - in the sense that someone _else_ emitting some CO2 and you planting a tree don't offset each other. The contribution to CO2 sums up to zero (or not exactly zero but nevermind) - but the _actions_ don't offset each other.