If all of the CO2 we sequester eventually leaks back into the atmosphere, then all we are really doing is time-shifting emissions. We’re putting CO2 in today. and it’s leaking out 100 years or 200 years from now. How can we put a value on the time-shifting of an emission? This is not simply a question of economics. One advantage might be that it would give us time to invent new, carbon-emission-free energy technologies. It might be worth reducing emissions in the short term in anticipation of new energy technologies coming online in the long term.