There is no doubt significant species loss due to humanity's effect on nature is occurring. But is that all there is to it? British conservation biologist Chris Thomas has published a book, Inheritors of the Earth: How Nature Is Thriving in an Age of Mass Extinction. that argues that a focus on species loss misses what has been accompanying these losses: a remarkable genesis of new species as nature adapts to the new environments we have created. It's an excellent read with many vivid examples of the dynamic he describes and much surprising information about the continuing ebb and flow of species in different areas of the globe.
Vox published an interview with Thomas awhile ago that gives a flavor of his argument and may interest you in checking out his book.
"We shouldn't take the existing state of the world, or how we imagined the world was a few centuries ago, as some correct state of the world. We are changing the world so dramatically, and species have moved into all sorts of new environments — well, that is what has always happened in the geological past. It's no longer realistic to think we can stop the change. It's like nature's healing process. When we see things changing, one attitude is, “Oh, the whole world is going wrong.” The other attitude is that nature is adjusting to a new situation....
You can't treat humans and nature in isolation. We should look on change for exactly what it is: change, not loss. We should ask is it objectively worse in some way than it was previously? Britain has 1,500 extra species of plants growing in the wild. Large numbers of conservationists regard that as a bad thing. I find it rather difficult to understand why having so many more wild plants is in any objective sense a bad thing. On something that I can actually measure, is it worse? Nature survives by being flexible and moving, and we should facilitate that flexibility if it makes ecosystems more robust and potentially more useful to us.
My bottom line is that there are biological losses going on on the planet. It is very rational to fight those losses, particularly when it is the loss of an entire species that may be difficult or impossible to get back in the future and which may have some unknown future value to us. But we are also living in a world in which there are biological gains. It is equally valid to celebrate biological life forms that are doing well in the presence of humans, rather than simply to resent these species and somehow prevent them from becoming the new biological success stories of the human epoch."