If methane numbers have been underestimated, it is very likely that so have nitrous oxide (300x more potent GHG) numbers and, as such, the total GHG contribution from all of animal agriculture. It doesn't matter if it's pasture-bred/raised, animal agriculture is wreaking havoc on the environment. The one action anyone can take to combat emissions from animal agriculture is to switch to organic, whole-foods plant-based foods.
How long will we continue to make excuses for our animal product consumption to the detriment of the planet and the billions of animal who are bred and suffer unnecessarily?