The world realized too late what we had done. Even though we saw the inevitability of the something that was coming. We thought it would be a nuclear holocaust, or perhaps an astrological one. We thought maybe pollution would do us in, or overpopulation; but no, it was the grass. Species that we introduced where they didn't belong, slowly crept up, took over, suffocated everything other green thing within their reach, and then slowly began to die themselves. Like with so many things, we didn't realize until it was too late, there was nothing we could do, nothing to be done. The animals continued to breath for a while, but then it got harder. Eventually, we all choked on our own ambition. I'm sorry.