The difference is that, barring time travel, there is nothing we can do to prevent the emission of a ton of CO2 that was emitted in 1020 (and even with time tra

The difference is that, barring time travel, there is nothing we can do to prevent the emission of a ton of CO2 that was emitted in 1020 (and even with time travel there is little contemporaneous technology we could replace it with.) But there is potentially a lot we can do (at various levels of cost) to prevent the emission of one ton of CO2 in any future year and the consequences of that additional emission may be disproportionately worse. Your own post acknowledges this, and it’s very much the point of the GP poster.