Nature became less and less as mankind grew.
It was a reckless growth, spurred on by the arrogance that came when we discovered that we had developed the tools to dominate other species. There was a great outcry when our population grew by another billion, but no one could be troubled to limit their reproduction or to safeguard the planet. The suspicion that every man looked out for only himself was quickly confirmed when we swallowed up all of our limited resources and overtook the earth like a boat being drowned by the sea.
When the trees had gone, we replaced them with great machines that allowed us to breathe while the oceans slowly asphyxiated. When the oceans were dead, we shrugged our massive shoulders and made a profit from the private farming of seafood, and were happy that we had a place to dump our increasing waste.
Endangered species such as the Giant Panda passed away.
They were novelties at best - we had more important things to worry about,
and besides, they could also be replaced with machines if people truly wanted worthless, pretty animals to look at.