Well we do move that 40 billion tons to the atmosphere. If we can do that, then in principle we can do the reverse. We just need an economic framework to pay for it.

It's certainly going to be cheaper, in most cases, to avoid emissions in the first place. But there will also be cases, like long-haul jets, where it may be cheaper to remove the CO2 later. Plus the CO2 is already above a safe level, so we'll have to draw it down somehow anyway.