I emailed an atmospheric methane professor about the NASA paper a couple of months ago, asking if it could be used for tracking permafrost thawing related methane leaks (in Siberia etc), and got this back:

"Yes, there is a lot of work on finding methane emissions by satellite. This is good as a broad guide to spotting big emissions like the huge US leak: the real problem we have is in quantifying emissions at ground level from a wide range of much smaller sources, and in placing good accurate numbers on the fluxes.

Unfortunately, the emission is from the ground into the boundary layer, at the bottom of the atmosphere, while satellite observation sees through the total column. We use wind back-trajectory analysis to identify the source of the methane (running the weather backwards), but there have been bad examples in the past where the media latched onto claims of major methane anomalies seen from space (e.g. in the Arctic or in S America) and didn’t realise that the methane was in the mid-troposphere in air that had last been in contact with the ground many thousands of miles away.

What is needed is an integrated approach at all levels, using satellite observation, wind-tracking using chemical transport models, and careful ground measurement to identify sources."

Assuming there is a law. I think we can already detect methane well enough to know that cows make a lot of it.

You don't want to make the law something they must "escape" from, but rather something they can profit from by not polluting. Like tax credits.

I disagree. I think we need to increasingly shift to pollution taxes because 1) physical pollution is hard to hide and 2) minimising pollution both improves the environment and maximises industrial efficiency.

This new result could push things along, because it provides the solution without lowering production. There would be less lobbying and backlash against such measures if the industry has clear way of dealing with them.