This is very one sides - not necessarily wrong, but in general simple solutions to complex problems are wrong and this pushing of biochar/coal is likely to be another one. Maybe part of the solution but not enough alone.
If you've ever seen cowpies sprouting grass out in some arid, quasi-desert environment, it's because their droppings contain grass seeds, insect eggs, worms, bacteria, fungal spores, and raw nutrients. Droppings are like ecosystem spores; they can help the originating ecosystem bootstrap itself in a new area, complete with hundreds if not thousands of species of microbiota, plants, insects, etc. Life is a team sport.