Grass-fed beef is worse for the environment than feedlot beef, which is already pretty damned terrible. You need more cows to produce the same amount of beef, which means more methane emissions. There isn't enough pasture land available to meet our demand for beef; cattle farming is already the primary cause of deforestation, which would only be exacerbated by a shift away from feedlots.

There is no ethical way to eat beef.

https://iopscience.iop.org/article/10.1088/1748-9326/aad401

https://www.ucsusa.org/global-warming/stop-deforestation/wha...

https://www.fcrn.org.uk/sites/default/files/project-files/fc...