But isn't that the natural way, you inquire; species go extinct all the time, evolution never stops, survival of the fittest & all that, what's the big deal. Of course, but that is the process of natural selection. We humans have become aware of the process (and conscious of how disproportionally we influence it!) and thus in a way transcended it (although a good case could be made that we, as a species, are still firmly subject to evolutionary processes: anthropologists studying big cities, for example, discover behavioural patterns in the multitudes, not unlike a beehive or anthill. Zoom out enough and there will always be a pattern). The main problem remains, however: we are conscious of what we could - and should - do, but blithely continue worsening the situation anyway. I'd call that harmful with malicious intent.
So all the time, like some cancerous growth, humanity inexorably expands beyond the limits of natural resources and continues to raze the planet like a biblical plague. I can't imagine the amount of human beings that would result in a ESS (evolutionary stable strategy), but I'm pretty sure 7 billion is way over the limit. In the brilliant but harsh British TV series Utopia, a plan is introduced to sterilize the world population (excepting a small selected group, that is); it's not so hard to see that this idea has a certain realistic merit and would appeal to many people - if often for the wrong reasons. Scientists are busy looking for earth-like planets, whither a selected and privileged few of us could embark after Earth has been plundered and scavenged beyond salvage, but wouldn't that be just like the ark story, where god resets the earth but still uses those same old and unbelievably problematic humans to repopulate? We'd just take the root problem - our divided and self-destructive natures - with us, like a disease or genetic defect. I would suggest prioritizing an attempt at harnessing our darker side, educating and elucidating ourselves, seriously slimming down the global population, creating better living conditions for everyone (including other animals) and trying to repair the damage at home instead.