So only looking at the byproducts of methane combustion is also misleading since nat. gas plants largely aren't burning methane - and blanket statements for all natural gas are also misleading since e.g. the gas from Canada is extremely 'Sour' and releases a ton of sulfur compounds when burned, often with fewer scrubbers than coal plants.
Methane will eventually break down into CO2, so if you look at the GWP for years 13-100, it’s 1. The weighted average for years 1-100 is over 20x, so it follows that if you look only at a shorter time frame, it would be dramatically higher and is indeed - somewhere north or 80 for a 20-year time frame.
https://www.epa.gov/ghgemissions/understanding-global-warmin...
As far as sour gas is concerned - not all natural gas formations are created equal. If you look at any serious pollution evaluation, they take into account which formation the gas was harvested from. Texas gas is pretty ‘sweet’ with low sulfur and acid content but much of the oil/gas in Western Canada or the Gulf is ‘sour’ and must be treated and refined prior to being sold as fuel. So it also follows here that flaring methane from sour fields is going to release a bunch of the souring compounds and have a much stronger environmental impact as compared to sweet formations.
https://nsrp.vn/latest-article/sour-crude-oil-and-sweet-crud...