Human population growth may be the largest threat to earth ecosystems. We develop land for living space, business operations, government use, transportation, waste disposal, recreation, agriculture, energy production, and mining. We are also depleting wildlife for food and profit. Population growth is probably not sustainable at the current rate.

Google World Population Counter:

    U.S. Census Bureau - U.S. & World Population Clocks

    U.S. Census Bureau - U.S. POPClock Projection

    U.S. Census Bureau - World POPClock Projection

    Population by Country

    Worst Environmental Problem? Overpopulation, Experts Say

    U.N. Study Ends Overpopulation Fears?

    Family Planning: A Major Environmental Emphasis