Metaculus Help: Spread the word
If you like Metaculus, tell your friends! Share this question via Facebook, Twitter, or Reddit.
What year will the 2˚C climate threshold be crossed?
At the Paris climate accord, world leaders promised to keep the global temperature increase this century (relative to pre-industrial levels) "well below 2 ˚C". Many experts were (and are) skeptical about this being feasible. Hence, it was asked whether there would be 5 consecutive years in which the global temperature was at least 2 ˚C above pre-industrial levels by 2100. As of the writing of this question, the Metaculus community assigns an 80% probability to this happening. The year of comparison chosen was 1880.
Here, it is asked: In what year will the average global temperature be at least 2 ˚C above the 1880 value for the first time?
Note that the answer to this question could be never and that a non-never resolution could occur without triggering a positive resolution to the previously mentioned binary question. In the case of a non-never resolution, December 31st of the first year to achieve 2 ˚C warming shall be used as the resolution date.
Data for resolution shall come from NASA, if possible. Note that the data in the link is normalized relative to the 1951-1980 baseline and 1880 stands at -0.19, so the critical value to look for is 1.81 (for temperature anomaly). It is possible, though, that the linked-to data source will no longer be available in a few years, in which case the best alternative (as of the judgement of Metaculus staff) shall be used for resolution.
Closing date is set to 2025, but should resolution triggering information become available earlier, the question shall close retroactively one year prior to that information becoming available. (In all cases in which the question was still open at some point within one year of the information becoming available.)
Metaculus help: Predicting
Predictions are the heart of Metaculus. Predicting is how you contribute to the wisdom of the crowd, and how you earn points and build up your personal Metaculus track record.
The basics of predicting are very simple: move the slider to best match the likelihood of the outcome, and click predict. You can predict as often as you want, and you're encouraged to change your mind when new information becomes available.
The displayed score is split into current points and total points. Current points show how much your prediction is worth now, whereas total points show the combined worth of all of your predictions over the lifetime of the question. The scoring details are available on the FAQ.
Note: this question resolved before its original close time. All of your predictions came after the resolution, so you did not gain (or lose) any points for it.
Note: this question resolved before its original close time. You earned points up until the question resolution, but not afterwards.
This question is not yet open for predictions.
Metaculus help: Community Stats
Use the community stats to get a better sense of the community consensus (or lack thereof) for this question. Sometimes people have wildly different ideas about the likely outcomes, and sometimes people are in close agreement. There are even times when the community seems very certain of uncertainty, like when everyone agrees that event is only 50% likely to happen.
When you make a prediction, check the community stats to see where you land. If your prediction is an outlier, might there be something you're overlooking that others have seen? Or do you have special insight that others are lacking? Either way, it might be a good idea to join the discussion in the comments.
Embed this question
You can use the below code snippet to embed this question on your own webpage. Feel free to change the height and width to suit your needs.