Pretty much all animal agriculture is horrible for the environment (and many other things including the animals themselves), but cattle ranching is certainly one of the most egregious offenders. Vast parts of the US Western states are Federal lands that are leased to cattle ranchers for pennies on the dollar. These lands are kept barren but for grass for the cattle to eat. All of the native residents of the land – deer, elk, wolves, foxes, coyotes, beavers and even eagles – are viewed as threats or competitors to the ranchers profits, so they are eradicated (murdered) by the ranchers, usually with plenty of help from the government.
In places where these lands have been reclaimed from the ranchers, and a few native species were reintroduced, the lands quickly grew into complex and sustainable ecosystems in a short amount of time. These areas help protect us from the climate crisis by taking millions of pounds of methane produced by the cattle out of the environment and holding carbon in the ground, They also preserve and expand biodiversity, provide billions of excellent pollinators, and greatly reduce water shortages.
We vegans and our allies need to take the lead on this. Really, it's so simple. We just need to get beef and dairy off of our plates, persuade our friends and family to do the same, and petition our leaders to reduce subsidies to the ranchers and to begin to reclaim land back to subsidize our children's future. We can do this!