This depends on what you mean by ‘destroyed’… a lot of people would say that by using up lots of fossil fuels (petrol, coal, gas), burning of which emits carbon dioxide (which causes ‘global warming’), and not resuing and recycling as much waste as possible, that we are effectively making our planet uninhabitable for ourselves and many other species.
I grew up in the 60s, 70s and early 80s when the Cold War meant that we all thought the big risk of destroying the world was from nuclear world war. My parents told me that the Cuban Missile Crisis (when I was two years old, and my little brother was just a baby) was the time they had thought the whole world might go up in a nuclear fireball.
It’s quite ironic – and really depressing – that now, when the danger of nuclear war seems to have receded, we’re facing the prospect of humans basically bleeding the planet dry and making it uninhabitable via resource exhaustion, habitat destruction and climate change.
To be honest, no matter what we do the planet will be here long after the human race has become extinct. Until the sun blows up into a red giant and incinerates the planet’s surface. But that’s not for another 5 billion years or so, so not anytime soon. I agree with Sarah and Austin that we are doing a lot to damage the earth’s biosphere and probably changing it irrevocably. But I am an optimist and I believe that the earth has survived bigger extinction events than us, and will recover in time. The types of species that are around will change, but life will go on regardless.