I guess in a way that depends on how you define "drastic". Are we changing the environment? I believe so, but really, who can say? We have a lot of evidence that seems to suggest that we do, but on such a short timescale, we cannot possibly think we have definitive proof. The hole in the ozone layer over the antarctic that people were convinced was a harbinger of the apocalypse 20 years ago? We didn't even start measuring it until 1956. Did CFCs really cause it, or has it existed in various forms for millions of years? We don't know. We've been measuring the world around us consistently for, at most, 500 years. That's like measuring the last ten seconds of the past 2.5 years. And even though our techniques for reading the past are getting better, the readings are getting more complex. So how much are we changing the world? We have absolutely no idea - because we just don't have enough data to compare it against.
If we lived in 17th century London, we'd have thought the Earth wouldn't last in its current state another 50 years.
Not to put too fine a point on it, but your statement uses "wonderfully diverse" and "interesting" - both of which are highly human-centered concepts. I am no stranger to aesthetics, and I would certainly mourn the loss of all the wondrous species that give our planet such rich (in our minds) diversity. But if you take us and our emotional attachment to the status quo out of the equation, it's quickly apparent that the Earth has no sense of aesthetics, nor does it care about biodiversity. Only the creatures that depend on it do. And even with all of our bombs, guns, pesticides, artificial chemicals, and everything else, nature is capable of so much grander scales of catastrophe than we can produce that it dwarfs our efforts in comparison. Volcanoes produce as much as 1/3rd the pollutants humans currently do... and have been doing it for 10,000,000 times as long.
We are stewards of the Earth, but most certainly not masters of it. We have an inflated sense of self, and an inflated sense of our own impact. We should do what we can to preserve what we can, because that is important to us - but we should do it knowing that it is only because it is important to us that it needs to be done, and not because the world around us cares a whit for our meddling.