One of the things you learn getting an anthropology degree (2nd most useless degree on the planet, by the way) is just how trashy humanity is.
A real common misconception is that previous generations were somehow neater, respected the environment more, or used up fewer resources. Absolutely none of it is true. One reason for the perception that we are trashier than our ancestors is that their trash biodegraded, and ours doesn't. The other is that there are just a whole lot more of us than there ever were of them. Something like 20% of all the people that ever lived are alive today. More folks, more trash.
And don't give me this crap about how Native Americans were more careful with the environment than the awful invading white guys. Entire cultures in Mesoamerica broke down because they used up all their resources and didn't have anywhere to put the trash. We don't find ancient American Indian sites because they have giant "WE WERE HERE ->" signs sticking out of them. We find them because the trash piles got so huge they end up being the most prominent part of what's left. Even tiny overnight camps are easy to spot because the hunters would stop to make and sharpen stone points. Do you really think they cleaned up after themselves?
The trash heaps outside the walls of ancient Jerusalem were so famous and so foul they became a synonym for hell. The streets of Roman cities were so covered in filth that they put raised crosswalks across them, with cuts through them to allow carts to pass. In medieval England it was dangerous to walk on the sidewalks because people thought nothing of emptying full chamber pots from the top windows. Out the front of the house. Dead bodies would pile up, not just of animals but of people as well.
Africans and Arabs got so good at "preserving" the environment that the Sahara desert expanded from a sandy spot in the center of Africa to a continent-spanning wasteland.
And don't give me all this crap about "the US consumes 1/3rd of all the energy produced by the world so it should be making the most strenuous efforts at keeping the environment clean." Guess what chief; we're the largest economy in the world. We produce stuff with all that energy. More stuff than anybody in the world. And do you really think that all these countries that have been tearing their shirts about Bush dumping the Kyoto treaty have been hugging trees all this time? The truth is, in the 1960s and 1970s, when the US was putting the screws to all heavy industry, the rest of the world was merrily polluting along its own way.
It wasn't until the late 1980s that Europe started taking all this stuff seriously, and really only the last ten years that it's made a difference. The only reason they want treaties now is that they were able to guilt the previous administration into agreeing to the US taking on a much higher share of the antipollution efforts. And of course you know that they would make absolutely sure that none of their industries took advantage of any competitive advantage this might give them! How dare you suggest such a thing! We're all just looking out for the environment here! Pay no attention to the French run factories in India, the unregulated Korean industries in Malaysia, or the Brazilian smokestacks belching poison. Nothing to see here, move along.
Do we need to conserve more? Of course we do, don't be stupid. There's six times as many of us on this planet, and our garbage doesn't rot anymore. But lets just everyone take care of our own houses, yes? After all, if we all made sure our air was cleaner than the next place's, the world would take care of itself.