I saw this post on /r/SSC, and the diagram looks pretty dramatic. But I don't know much about it. Haven't seen people discussing it before, which I would've used to take as a sign that it is not so significant, but I don't know anymore.
Let's have a market on it. This market resolves YES if it matters, such as if:
This is the beginning of runaway global warming
This is the beginning of some non-runaway phase shift in global warming that is going to suddenly lead to a lot of damage
Rationalists broadly acknowledge that this spike is uniquely important for other reasons
This market resolves NO if it doesn't matter, such as if:
The spike disappears in future data
The spike remains but turns out to be misleading/meaningless
Related questions
@tailcalled I don't know yet whether it's that important, but I think it's been argued that this is due to some accidental geoengineering via atmospheric sulfur injection from marine fuels being halted by new regulations on their sulfur content, so it will at least probably not go away soon.