It's not absolutely clear from the comments here whether you settled on 'average for all of 2025' or 'single day/week/month in 2025'.

I am assuming that it is global yearly average as done in, https://gml.noaa.gov/webdata/ccgg/trends/co2/co2_annmean_gl.txt

as there is a lot of variation from both seasons and the different observatories.

Based on annual trend data from:

https://gml.noaa.gov/webdata/ccgg/trends/co2/co2_gr_gl.txt

and the 2022 avg. of 417.06 from the first data set, it would have to increase by an annual average of about 2.65ppm per year for three years to exceed 425. Based on the trend data, I find this unlikely, so I am betting No. If the market description changes dor becomes more specific, I will update. Edit: I fixed my calculation to more decimal places (too much app crashing), it makes it much closer as looking at the last decade annual increase where it was about 2.4ppm, with an upward trend - eyeballing this at 2.5 is where I would put my prediction as the decadal mean for annual increase for 2020-2030, but 2.65 is not unreasonable. As of now I would bet it being about 424.56 ppm in 2025 (3*2.5 + 417.06).

@parhizj Yes daily weekly and monthly numbers are certain to exceed 425 in 2025 whereas annual average looks to be sensible.

a bit of a bounce back from low increase in 2022 seems likely.

@parhizj Yes, that was my intention. I think global yearly average makes most sense in terms of influence on global climate and NOAA seems like a decent source for resolution.

data source? is resolution based on daily co2 reading at ANY point during 2025 or mean atmospheric concentration during the year? shouldn't the market close 01-01-2026?

@lumi Undecided on data source, but other commenters point to NOAA as a good option. The intent of the question was to get at the drivers of global climate change, for which global mean during the year seems most relevant. I'm not that interested in local or seasonal fluctuations.

@lumi I set the close date at the start of the year since I don't want traders to be discouraged from buying if they don't think they will be around to react quickly to any announcements of measurements that would cause resolution in the year.

@RobinFoster Closed is the same as being 'open but resolutely refusing to bet any more'. You can choose to do latter if you wish if it is left open. The differences are you cannot cash in your holding, nor choose to bet during last year if it is closed. These both seem disadvantages

To explain a little further: To avoid a more active person taking advantage of you when announcements come out, you should not leave open book orders at these times. It is quite possible to do this if the market is left open, just don't leave open book orders.

@ChristopherRandles Hmm, yes. This makes sense. I guess I was thinking by analogy with sports matches where I'd rather not bet on an exchange where someone else watching the match can react to that information faster than me, who is busy doing other things. But if no-one can react to information (the market is closed) that doesn't actually matter.

Other comments welcome! Would other traders prefer this market to close at the end of 2025 or do you prefer the end 2024 close?