Suppose you have any finite number of humans to work on the problem.
Emissions reductions can be achieved in known ways at some relatively modest cost, e.g. the difference in cost between using fossil fuels and using electric cars or renewable/nuclear generation methods, which are already very close together in price and could be made closer or even cause the alternatives to cost less through certain types of engineering R&D or reasonable regulatory changes, and not only lower emissions but lower energy costs.
Carbon capture requires a large amount of R&D which might not yield any useful results whatsoever, and if it did the result would be a reduction in cost from a level which is hopeless and preposterous to one where actually deploying it would still cost trillions of dollars in implementation and operating costs to have any meaningful effect, while producing no other economic value and almost certainly a vast amount of chemical waste.
The difference in cost effectiveness is so vast that the optimal allocation of finite resources to the latter could plausibly be zero.
