1. Can be solved with phytoplankton, and separately also by more land-area-efficient farming e.g. greenhouses, 2. Can be improved with genetic engineering.
Do the right generic engineering and you even get the oil feedstocks you need for plastics. You could even put the algae in a tube on a rooftop as an alternative to PV, if you could resolve the issue of unwanted other phytoplankton getting in and gumming it up.
A lot of agricultural land is wasted growing crops to feed to animals. If we were to lower meat consumption, agriculture land could be freed for other uses without taking away poor people’s food supply.
The problem is to do with things called "numbers".
1. There is no spare land to devote to CC. You could do this only at the cost of poor people's food supply.
2. The rate at which plants remove CO2 from the air is very low. Far too low to solve the problem.