It breaks down by half over 7 years. 7 years is the half life not the lifespan. Also yes it continues being a greenhouse gas even after it breaks down. So the "Global warming potential" of a ton of methane leaked to atmosphere starts out extremely high.
(Edit: I misunderstood this next part. It's potencies here are averaged over that period of time. Most of the impact comes at the begining.)
After 20 years it is 86x more potent than co2 and after 100 years it is 34x more potent. It never becomes less potent than co2 because it eventually becomes co2.
(Edit: I misunderstood this next part. It's potencies here are averaged over that period of time. Most of the impact comes at the begining.)
After 20 years it is 86x more potent than co2 and after 100 years it is 34x more potent. It never becomes less potent than co2 because it eventually becomes co2.