In terms of climate change it’s not a 10 years thing and then methane instantly swaps, it’s a second by second thing where a percentage of existing methane is constantly converted. In steady state new methane from say cow farts 1:1 replaces methane from past cow farts being transformed into CO2. The only difference is an atom of CH4 at 16.043 grams per mol weigh less than an atom of CO2 at 44.009 grams per mol. Though many sources of CH4 start by extracting atmospheric CO2, natural gas leaks don’t.
The critical difference is if we cut net CO2 and hold methane steady the atmosphere stops warming, where cutting methane and CO2 would actually cool the atmosphere.
Put another way NEW sources of methane are different because it takes multiple years to reach an equilibrium. In the first years they have a very big impact, but eventually it falls off until eventually a constant source of CO2 may actually have a larger impact.
Why the US? Shale gas is based on an enormous number of gas wells with a short lifetime each. It's not economical to provide power and compressed air at each of these shale gas wells, so they use the pressure of the natural gas as the energy source to actuate their valves and pump liquids. That means the gas is vented to the atmosphere. And any liquids storage is in tanks which have no blanketing, so any evaporation and associated gas goes straight to the atmosphere.
US shale gas has incredibly high methane intensity. Not quite as bad as Russia, but worse than the rest of the world, including Saudia Arabia.
LNG plants themselves tend to have fairly low methane emissions. If you go to Qatar or Australia, the other two leading LNG exporters, their CO2 emissions will be high, but due to their upstream facilities they will have a tiny fraction of the methane emissions of US production.
But it's cheaper and easier to just engage in finger-wagging, pledges and vague ESG-inspired aspirations that to pay more for less-GHG-intensive LNG, so nothing will change in the short term.
https://www.esa.int/Applications/Observing_the_Earth/Coperni...
