A comprehensive carbon tax that's more expensive than CO2 sequestration will solve the problem by itself (or rather by market forces, everyone will either optimize away emissions or offset them with sequestration rather than pay the tax). For that we need a sequestration method that's cheap enough that a comprehensive CO2 tax at that price point is viable and won't be riddled with loopholes. $50/ton is still a bit high for that, but it's a lot closer than other methods we have so far.