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
1,000People are also trading
Almost normal after ~1.7 years?
https://climatereanalyzer.org/clim/sst_daily/?dm_id=natlan
Is that "The spike disappears in future data"? Not convinced yet - might be a temporary dip back towards a more normal 'near top edge of other years temperatures' with the dip due to La Nina. Also because:
There is still a puzzle as to what is happening:
https://www.bbc.co.uk/news/articles/cwyjk92w9k1o
A puzzle as to what is going on is a long long way from "the beginning of runaway global warming".
To "to suddenly lead to a lot of damage" is rather open to interpretation, how sudden? How much is a lot? I would suggest from severity of other scenarios suggested that this is meant to be a 'whole lot of damage' which we are not close to yet.
"spike is uniquely important for other reasons"
Far more likely it is a combination of a few factors eg Marine emissions 70% cut in sulphates starting 2020, a bit of solar forcing, El Nino effects longer lasting for some unknown reasons and so on. Reaching a level of "uniquely important" seems unlikely to me at present.
Seems like pretty high bar has been set for yes and we are not approaching that yet.
@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.