I do love George Monbiot, I've just finished 'Feral' and that has a lot of interesting ideas in it.
But he is on the extreme edge of conservation and rewilding and ecology, so although he's always worth listening to, you will find other writings that are more middle ground.
Eco-warnings are depressing because it takes so long for anyone other than enthusiasts to get their arses into gear and do something about it, and you're nbattling against very wealthy interests that don't want change or sistainability if it inconveniences them or lowers profit.