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.
It’s a question of scale. Methane is useful fuel, so leaks are an exception rather than the most common result. Spilled gasoline when fueling your car also results in atmospheric CO2, but you produce vastly more CO2 from what ends up in your tank.
There is plenty of evidence that leakyness is a common feature of natural gas infrastructure.
The Methane being leaked is 86x more potent than co2 over 20 years and 34x more potent over 100 years.
At 1% leakage todays natural gas emissions don't gain a climate advantage over coal until around 2100. At 2% leakage todays natural gas emissions are still significantly worse than coal in 2100.
Interesting. Oil companies frack to get petroleum, and are OK with burning the natural gas at the well head. I get the impression that a big reason they choose to capture the natural gas instead is criticism of just burning it by environmentalists, but maybe it is more environmentally friendly to just burn it in the absence of the political will to ban fracking. (I am assuming that burning at the well head is an effective way to reduce the amount of unburnt gas released.)
They flare it where there is no infrastructure or insufficient infrastructure to get the gas to market. There are limits on what can be flared and this is what drives some of the decision making. However, if sufficient infrastructure exists they are literally burning money by flaring the gas or just letting it evaporate into the atmosphere.
