"previous 25 years" including 2023?

@StevenK yes

On average the temperature is surely increasing, but the yearly average temp tends to be a bit of a sawtooth/zigzag where on the years that it sets a record, it increases more, whereas non-record years are only slightly cooler.
So 50-60% seems reasonable to me, so I bid it down.

I also recalled another market where I think I could do a bit of arbitrage against it, and hence avoid a ruinous outcome.