Resolves positive if the long-run [20 year] global mean temperature average raises more than 2.5°C vs. the 1850-1900 average before 2050
Resolves negative otherwise
https://web.archive.org/web/20220518083042/https://library.wmo.int/doc_num.php?explnum_id=11178
If the temperature reaches the threshold, then falls back below that level the contract still resolves positive.
The temperature must heat more than the threshold in the title for the contract to resolve positive, to whatever precision measured. So, if a reputable source gives the midpoint temperature increase as 2.51°C, the contrast will resolve positive, but not if the source lists 2.50°C. If the source uses a confidence interval, the contract will resolve based on the reported midpoint.
see also:
Will the climate heat up more than 2°C by 2050?
https://manifold.markets/B/will-the-climate-heat-up-more-than-4a9f7174817a
Will the climate heat up by more than 2.5°C by 2050?
Will the climate heat up more than 3°C by 2050?
Will the climate heat up more than 3.5°C by 2050?
Will the climate heat up more than 2°C by 2100?
Will the climate heat up more than 2.5°C by 2100?
Will the climate heat up more than 3°C by 2100?
Will the climate heat up more than 3.5°C by 2100?
Will the climate heat up more than 4°C by 2100?
Current policies are expected to result in 2.5-2.9C by 2100.
https://climateactiontracker.org/global/temperatures/
Certainly won't happen by 2050, and may not happen ever if the world gets its shit together.