AP photo/Mahesh Kumar A

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With the demands currently being placed on it, the planet is having an increasingly tough time getting by, let alone sustaining the number of people living on it. Between the nearly 80 million people added to the planet every year, and recent calculations projecting a population of 7 billion by 2011, prospects for a healthy future are not great. We are running out of resources, and polluting the only environment we have to live in. Some areas have been so contaminated or depleted of their natural resources, especially water and trees, that it is expected to be impossible to replenish them, if serious change does not happen soon--if it is not too late already.

The UN has been issuing warnings for years now, and upon the release of a 2007 report, the director of the Environment Program said, "The human population is now so large that the amount of resources needed to sustain it exceeds what is available at current consumption patterns."

Diminishing Returns

In 1900, 7.91 hectares of land was available for every person, and by 2005 that share had dropped to 2.02 hectares, and is expected to fall further to 1.63 by 2050. Demand for resources, however, has only been growing, and stands at about 22 hectares per person. Not exactly sustainable.

Feeding the population has become an increasingly difficult task, especially as regions that already struggle agriculturally, Africa in particular, become drier because of global warming. With animals going extinct faster than ever, biodiversity is plummeting. Some have predicted that the oceans will be depleted of all the species now being fished if current consumption and fishing practices continue, since, according to the same UN report, we are catching 250 percent more fish than the oceans can produce. Also associated with population-induced environmental degradation are the "dead zones"--areas that cannot support marine life because of depleted oxygen supplies--that have expanded and multiplied around the world.

On top of all that, population growth is blamed for the resurgence of some diseases as well. Over-reliance on things like drugs and insecticides has eliminated symptoms rather than risks, and of course the more crowded cities become, the more easily illnesses are transmitted.

The damage will be irreversible if sufficient action is not taken immediately, and the magic number, according to leading scientists, is 350. That's the safe upper limit for carbon, measured in parts per million, that our atmosphere can handle before the harm caused by climate change is completely irreversible.

Watch Focus Earth: Population Overload