That is an ephemeral change. It takes very little time for the biosphere to make a full recovery. You're talking about a small, brief, suppression of the biosphere. And you're calling it "destruction of the biosphere".
Even if you're talking about the fires in Yellowstone in 1988, the only way to call that "destruction of the forest" is if you define the forest as being the trees. That's a defensible choice.
(And temperate forests "burn down" all the time as part of their normal operations.)
But you can't define the biosphere as "the species that go extinct in a particular scenario". You're stuck with the whole thing, which is not going to notice whatever humans do. It would make as much sense to call it "destruction of the biosphere" if I moved a rock thirty feet.
