This is the fundamental problem with green ideologues, they think that the biosphere is static and that life is impossible if it changes. You need to wrap your head around some facts. Mass extinctions created the current biosphere. If you think mass extinctions are bad, you must by extension think that the current biosphere you currently hold next to sacred is also ultimately a perversion of the state of life before said extinctions.
If the thrust of your argument is that "environmentalists are stupid because they're not okay with mass extinctions," then... um, okay. I suppose we'll have to agree to disagree - anyone not okay with mass extinctions on my side.
I have to say, though, that I thought you were setting up to make an "environmentalists are the REAL bad guys because they oppose mass extinctions, which usually lead to increases in biodiversity, which means that you stupid greenies are ANTI-EVOLUTION and ANTI-LIFE, man!" I'm a little disappointed, because that would have been worth a few extra comedy points.
Life can spring back from virtually nothing. During the greatest mass extinction, 90% of ocean-dwelling species perished completely. Have you noticed how they're not still empty? More importantly, have you noticed how there are a lot more species in the oceans now than in the Permian? Over time, biodiversity has always increased, regardless of how severe any event has been over short periods.
The implication being that following a catastrophic collapse of the ecosystem due to climate change, lots of life forms will bounce back nicely. That's a safe bet on two counts. First, because I don't know of anyone suggesting that everything down to single celled organisms will die off, and then a few million years later we're back where we started, only with merfolk or whatever. And second, because either way, all the humans are likely to be dead, so who is going to call you on it if you're wrong?