[newt_slowly]

> So how can it be feasible to afford enough energy to "unburn" a century's worth of burnt carbon if we can't even get enough energy to avoid burning new carbon in the first place?

It isn't, and it won't be. Carbon capture is a pleasing myth we tell ourselves to avoid the massive and immediate actions that would be necessary to avert catastrophe.

We're addicted to fossil fuels, telling ourselves that when we eventually sober up we can undo the damage we've done to ourselves.

[imtringued]

Carbon capture will never lead to negative emissions. What it will do is merely capture CO2 at central locations for processes that have no alternative.

[epistasis]

I sincerely hope you are wrong, because if you are not, we will never keep to less than 1.5C of warming. Every single pathway for that requires carbon capture above and beyond what we can do with terrestrial processes.

There are several startups trying to come up with ways of sequestering atmospheric carbon in ways that will last for thousands of years. We need something like that to work, and to come up with ways to fund massive deployment in the second half of this century.

[PeterisP]

Well, we probably will not keep to less than 1.5C of warming, e.g. in the IPCC report even the most optimistic (i.e. unrealistic) scenario has a most likely estimate of 1.6C of warming.

IMHO when estimating future, starting with the desired outcome (or even considering it much) is harmful, as it causes you to accept unrealistic assumptions and estimates for the key items driving your predictions, just so the predictions will come out as "acceptable" to you. You need to consider the impact factors as they are, and have realistic expectations of the effect and likelihood of interventions (especially considering the specific motivation factors of the narrow groups who can make each of those interventions, how that aligns with their interests), and see to what prognosis they lead you.

If we "need to come up with ways" then it means that it's plausible that we won't, and we (in this case, not we-as-the-world but we-as-individuals and we-as-smaller-communities) also need to plan on how to protect our interests in that (quite likely) scenario. An aching desire for something to work does not imply that it's possible in the required timeframe. Especially because there's no single "we"; those that need a solution to climate change and those that could fund it are largely separate groups; you can't look at it as a primarily technical problem when the largest impact factors are political.