The question only refers to CO2 sequestration via Direct Air Capture (DAC). The solution must be scalable. I'll define scalable as there existing somewhere in the world that "could" produce 100,000+ tonnes at such a price. There doesn't have to be such a system in place; there must only be consensus among experts that such a system is possible.
Current estimates are that CO2 costs between 600-1000 USD per tonne [1]. I will resolve this when the price drops to 60 USD per tonne adjusting for inflation. If the threshold is not clearly surpassed within one of the above periods, I reserve the right to resolve two time periods as being correct.
@Irigi I imagine there will be significant uncertainty over the exact time in which the prices drop to 60 USD / tonne. If the error bars overlap two of the time periods, I reserve the right to resolve two time periods as Yes. I imagine the uncertainty bars will be over months, not years. Therefore, I think it very unlikely beyond the first few options that I will resolve Yes to more than one option.
@ChrisCameron If we are not sure, should it rather be proportion? (E.g. resolving 50%-50%, or 70%-30%, depending on the uncertainty?)