Thread by @grazing_paige

Let's talk about GWP100 vs GWP* for short lived climate pollutants.

I see lots of folks in the regen grazing community latching onto this metric as a get-out-of-jail-free card on CH4, the one GHG area where grazing really suffers compared to conventional beef.

I often err on the conservative side of grazing & GHGs that way there's no question of methods.

GWP* is newish (not yet codified by IPCC GHG accounting, to my knowledge), but I do think it rectifies an important problem with CH4 as a short lived climate pollutant.

CH4 is a "flow" pollutant, meaning it doesn't accumulate in the atmosphere in the same way that "stock" pollutants like CO2 do. But GWP 100 doesn't take this into account.

In short, that means constant CH4 emissions will reach an equilibrium w/ atmospheric removals.

In the case of beef, as long as herd size isn't expanding (true in the US), then cattle aren't contributing as much to warming as GWP 100 would lead us to believe

On the flip side, this also means that CH4 reductions under GWP* cause pretty rapid declines in the rate of warming

"A key point emerges which is obscured by conventional use of GWP100: to prevent further warming, it's necessary that net CO2emissions are ⬇️ to 0, but this is not the case for CH4, where it's possible to have climatically sustainable ongoing emissions." iopscience.iop.org/article/10.108…

So yes, I think GWP* is a better measure of warming from short lived climate pollutants, but I don't think it absolves the beef industry from trying to ⬇️ CH4.

At the same time, I think we can better weight CH4 against other environmental impacts (i.e. soils) w/ this new info