Human dominance of biology

Many people suffer from the false image of a vast 'natural' world compared to a miniscule human influence. This is the reverse of the actual situation. The sun is the primary natural source of energy and variability, but it changes slowly. The overwhelming human influence on the planet is due to our success as a species and our ability to manipulate energy which have, in the last 200 years or so, yielded a large-animal population - us - at least 5 times larger than any previous species bigger than a cat has achieved. The only times the planet's biosphere has seen this rapid a change in the past have involved cataclysmic events like large meteor strikes.

Humans, at 6 plus billion and rising, are the commonest large animals on the planet. The next most commmon mammals are domestic livestock that total another 3 billion or so. Even pets, at 50 million dogs and 70 million cats in North America greatly outnumber the whitetail deer, the commonest large wild mammal at 15 million.
The total wild waterfowl population of North America is 70 million birds. North American poultry production is 14 million tons per year - over 100x as much. We, with our livestock, are overwhelmingly the large animal population of the world. We will thus overwhelm all other large animals in our influence on the world.

Since animals eat plants, it shouldn't be a surprise that the majority of land vegetation is planted and harvested by humans. Something that really brings this home, though, is the animation of primary production available at http://earthobservatory.nasa.gov/Newsroom/NPP/Images/npp_20012002_sm.mpg

Rainfall gets used for agriculture, manufacturing, and to wash down our habitation areas. All non-human usage combined about equals these totals. http://www.globalchange.umich.edu/globalchange2/current/lectures/freshwater_supply/freshwater.html

We are the dominant large animal life, the dominant plant life user, and the single largest users of fresh water. In addition we control energy out of proportion to other animal usage- several horsepower per person. Total CO2 output now providing this energy overwhelms natural sources,but to look at the energy itself take a look at the night sky view at
http://images.google.com/imgres?imgurl=http://www.phoenix5.org/gallery/earthlightsFull.jpg&imgrefurl=http://www.phoenix5.org/gallery/earthlights1500.html&h=296&w=591&sz=18&tbnid=VEumcq6aKN4J:&tbnh=66&tbnw=131&start=14&prev=/images%3Fq%3Dearth%2Bat%2Bnight%26hl%3Den%26lr%3D%26sa%3DG
and realize that this light is just wasteage from a small portion of our energy usage.

What we do, as the overwhelming variable in present-day earth's environment, is the most influencial factor in the world we will live in. Since no projection of earth's human population shows it as dropping, our influence will continue to be overwhelming for the forseeable future. The world is not human habitation spotted through a wilderness. It is cities, suburbs, farms and ranches with occasional parklands.