Every month, NASA´s website releases data about carbon dioxide (CO2) levels in the atmosphere, as measured at the Mauna Loa Observatory, Hawaii.
If data from the next report from NASA - expected to be released in the first half of October 2024 - indicates that the deseasonalized concentration of CO2 in Earth's atmosphere in September (with the average seasonal cycle removed) was greater than its concentration in August, this market will resolve to “Yes”.
Source: https://climate.nasa.gov/vital-signs/carbon-dioxide/
See the current crowd-generated prediction, and make your own bet: Atmospheric CO2 levels to grow in August?