Because "urgent system-wide transformation" is just a euphemism for war.
It's ironic that they criticize the current approach for not working, and then suggest a nebulous 'transformation' that has even less chance of working. Even if they created a communist revolution in the US, they would then need to extend this to the rest of the world which would likely involve wars that increase emissions.
https://aninjusticemag.com/is-revolution-necessary-to-move-f... https://aninjusticemag.com/is-free-market-capitalism-sustain...