Apparently humans have (effectively) killed off another species:
The white dolphin known as baiji, shy and nearly blind, dates back some 20 million years. Its disappearance is believed to be the first time in a half-century, since hunting killed off the Caribbean monk seal, that a large aquatic mammal has been driven to extinction.
A few baiji may still exist in their native Yangtze habitat in eastern China but not in sufficient numbers to breed and ward off extinction, said August Pfluger, the Swiss co-leader of the joint Chinese-foreign expedition.
"We have to accept the fact that the Baiji is functionally extinct. We lost the race," Pfluger said in a statement released by the expedition. "It is a tragedy, a loss not only for China,
but for the entire world. We are all incredibly sad."
I know that 95 percent of species that lived on the planet are now extinct! Don't get me wrong, I'm not upset because cute fuzzy animals are dying. I'm upset because the ebb and flow of nature has been stretched past its limits, and this is not good for Earth, not good for other species-- heck, it's not good for us. And there is no fixing this problem, unlike other human-wrought environmental changes; once a species is gone, it is gone forever.
Perhaps I'm not mature enough to form my arguments clearly enough (I'm still a teenager), but I hope I'm making sense.