While Methane has a shorter half-life it is also a much more effective GHG. The common way to look at this is Global Warming Potential, which is measure in CO2

While Methane has a shorter half-life it is also a much more effective GHG. The common way to look at this is Global Warming Potential, which is measure in CO2 equivalents. You can find this on the wikipedia: https://en.wikipedia.org/wiki/Global_warming_potential https://en.wikipedia.org/wiki/Global_warming_potential Notice that you can look at the GWP potential over time spans. For methane, over the next 100 years (which is the period that will impact most HNers the most) it is at least 20x as impactful as CO2. The reason this matters is because the biggest unknown with climate change is positive feed backs. A classic example of this is that as the arctic has less ice it also reduces the albedo of the oceans allowing them to absorb even more heat faster. Another, methane related, theoretical, positive feed back is methane clathrates which are essentially frozen stores of methane deep in the arctic ocean. If the ocean were to warm up enough this might rapidly release methane leading to a catastrophic runaway warming scenario, leading to what is suspected to have caused rapid climate change in the Quanternary period [1]. It is currently believed by many researchers that, in the specific case of the 'clathrate gun' firing, it is unlikely to happen. The trouble is we don't know for sure. That is just one unknown, potentially devastating positive feed back. If you read Peter Ward's work (and some others as well) it looks like at various times in the history of the planet there was very rapid, very destructive climate change that was caused by a cascading series of positive feed backs. We don't know exactly where these are, but the more methane we release (and CO2) and the faster the planet warms the more likely we are to find these. It is important to note also, that these positive feedbacks are not factored into the IPCC report (just like the potential collapse of Thwaites Glacier is not) because the is no way to effectively model this and make predictions about them. It means that if you think the IPCC report sounds bad (or even if you don't) there is a lot of potential risk not mentioned in the various pathways there. 1. https://en.wikipedia.org/wiki/Clathrate_gun_hypothesis https://en.wikipedia.org/wiki/Clathrate_gun_hypothesis