[stupendousyappi]

That's based on two very cautious geoengineering approaches that have virtually no negative side effects. If governments were willing to consider other geoengineering approaches, I think that number could be driven down significantly. My favorite candidate is ocean-wave-based olivine weathering, as proposed by Project Vesta. They think that, at scale, that approach could get costs down to $21/ton, plus reduce ocean acidification more effectively too. But it's more complicated and could have some negative effects, such as putting a lot of poisonous heavy metals like nickel in the ocean. But because politicians hate ever having to say that they're knowingly causing any problem, those avenues get starved of research funding, as we see here. But I think that, within 50 years, we're probably going to find a scalable CO2 removal approach for less than half the target cost of this program, and that basically could solve global warming, but because of political cowardice it's discovered 30 years later than it could have been.

Everyone wants to do emission reduction first and delay geoengineering as long as possible, when we should be doing the opposite. Even if the financial cost appears much smaller, it's clear now that large scale emission reduction is politically very expensive. Emission reduction is the clean, ideal solution that we don't have the ability to scalably implement yet. Geoengineering should be temporary quick and dirty approach we use to buy time, creating some problems that last decades in exchange for time to implement a solution for a problem that lasts for millennia. Assuming that cheap geoengineering techniques whose negative side effects are bounded in space and time can be found, but I think that they can.