> reducing carbon seems like it should be a much lower priority compared to how hard its pushed
I'm not sure what you mean. The last 50 years (and even 5) have been far more bark than bite.
> incoming nuclear fusion would alleviate a ton of our carbon issues
A bird in the hand is worth two in the bush. I worked on nuclear in a previous career and still have friends there, including fusion (including the big labs). Being bullish, fusion net gain is still 10 years away. It'll take decades to add to the energy portfolio after that. The case for fusion is worse than the case for fission. We should work on both, but we can't hold out for future technologies (we can say the same about storage). We needed to act decades ago, pushing it off by a few more decades is not going to solve the issue, it is repeating the same mistakes.
> fleshed out cost-benefit analysis
I wouldn't trust any of these. Zero of them. You need to have a pretty good understanding of these systems (highly complex) to even understand if the analyses are good. Every single one has a bias and is highly politicized. The more politicized a topic is, the higher level of expertise you need to understand who is telling the truth (politicization adds large amounts of noise).
> Bjorn Lomborg
Who is a political scientist. He isn't a climate scientist, nor even a scientist. Here's a rather well known scientist, Stefan Rahmstorf (studies physics of oceans) discussing Bjorn[0]. You can check Bjorn's scholar page[1] to even verify that he's not doing actual science bust just writing opinions with no supporting evidence. Please stop supporting hacks.
[0] https://www.realclimate.org/index.php/archives/2015/08/bjorn...
[1] https://scholar.google.com/citations?hl=en&user=HUMF5c0AAAAJ