Alright, let's see if I can convey my concerns in an orderly fashion.
1. Humans are a part of nature.
2. Humans are animals.
3. Humans therefore are subject to the laws of nature and function in the same manner as animals.
Typically in nature, when an animal population thrives, it grows at an exponential rate. This occurs for a period known as the "Net Growth" phase. This occurs until one or both of the following conditions are met: 1) There is little or no food left, or 2) There is so much waste that an outbreak of disease wipes out the majority of the population. Once this happens, we enter a period known as the "Net Death" phase, where the population collapses almost as fast as it grew.
The human population has tripled in the last century. There are now over 6 billion homo sapiens, most of them want to breed. Most of them want to eat. You see the problem here now, correct? If we divide that 6 billion into 4 assumptive factors: males, females, children, elderly, we have at least 3 billion potential babies. Within a generation or two, we'll have nine billion humans. Then 12. Then 18. Then 24...
There has to be a point when we reach one of those conditions. Some argue we already have. I prefer not to be as fatalistic.
The reality of the matter is that our industrial society is based on disposability and convenience, both have terrible consequences for both health and the enviroment. We are now generating more waste than the enviroment can handle. This is chiefly because we are demolishing the biosphere's ability to "digest" our wastes effectively at an alarming rate.
For the first time since anyone, including the resident amazonians apparantly, can remember, there is a drought in the rainforest. In an ecology that depends on rain to fall daily for months on end, this is catastrophe. For us, this the beginning of the sacrifice of 10-20% of the world's oxygen for the richness of a few and the ever needed "job" for everyone else.
This is why you should care; the economists and the cons and energy industries seem to think they can go on expanding and building products for your consumption forever. They seem to have no concept that all that paper is coming from wood, all that beef is coming from farmland from demolished rainforest, all that mercury is pilling up in oceans, etc. They don't see that resources can only be consumed at a rate they can be recovered at.
So what can you do? Recycle, recycle, recycle. 90% of people's garbage is recycleble (is that a word?) If it's paper, you can recycle it. If it's plastic, recycle. Food, you can garbage or compost. Something simple as recycling and using recycled paper can prevent trees from being cut down, providing us with more Carbon Dioxide (Greenhouse Gas emissions) breathing and oxygen exhaling trees to slow the tide of global warming.
The alternative concept is fairly easy to imaging. If we continue on our present course, eventually the weathern patterns will be altered enough to promote large scale drought conditions. Without food, people will stop being concerned about silly things like cds and movies. The economy will collapse. Governments will lose control. People will flock around those who can provide them food and protect them from preditors. These protectors will quickly become warlords. One of these bozos would eventually aquire the leftover nuclear warheads from our glorious civilization, and that's where the real problems would begin.
Nations less affected will of course also try to seize any nuclear assets left in the wake of a superpower crushed by famine. War would quickly follow a serious famine.
This is not doomsayer paranoia. This has happened to civilizations before. Mayan cities, the old kingdom of egypt, the Anazazi, the Nordic Greenland colonies; all these cultures appear to have fucked with their local ecologies (whether consiously or not) and made their lifestyles unlivable.
So there you have it. Remember, we are nature, we are natural beings, but we also are rational beings. Societies have changed before to suit new circumstances, and we can too. Just worry about what you gotta do, and the rest will work out fine.