7 Billion and Counting: Welcome to a Planet With Population Overload and Resources in Crisis [With Photos From National Geographic]

Editor's Note: View a photo slideshow at the end of this article from National Geographic magazine's new "7 Billion" app for iPad, based on its year-long series on world population.

Here's some freaky news: According to United Nations, Earth's seventh-billionth person could be born by Halloween, even though "the fire marshal only certified Earth for 6,999,999," according to a recent tweet from "The Daily Show." It's a clever joke hiding a tragicomic dimension of the uncertain achievement: The planet's increasingly inhospitable climate and depleted resources mean we have little room for more humans, especially the 10 billion or more expected to stress the planet's already overweight system by 2100.

"Let's assume the average weight, or mass, of a human is 50 kilograms, or 120 pounds," University of Washington paleontologist and The Flooded Earth author Peter Ward told AlterNet. "That takes into account all the fat men, and all the kids, so it's a ballpark figure. That means 350 billion kilograms, or 770 billion pounds, of humanity on the planet. I wonder if this is the highest mass of any chordate on Earth. Only rats might weigh more of all natural populations."

But even rats have the good sense to abandon a sinking ship. Not so for humanity, whose resource wars have created a hyperreal dragnet that has caught up everything from mass-media distractions like Herman Cain and Mommar Gaddafi to worthy insurgencies like Occupy Wall Street. As those stories, for better or worse, dominated the news cycle, British Petroleum was quietly freed to resume drilling in the Gulf of Mexico after turning it into a marine nightmare since 2010. Exxon Mobil posted a $31 billion profit on the year thanks to billions in groundless government subsidies. American rivers and streams have become hypersaturated with carbon dioxide, and Arctic sea ice has become as thin as the United States is fat in the gut and head. Environmentalists and other concerned parties can be forgiven for not breaking out the bubbly because the planet has managed to spawn seven billion souls with increased life expectancy, thanks to miracles of science and industry. Because in the scariest scenario, that same science and industry could doom most, and perhaps even all, of us.

"Seven billion is not a time for unbridled celebration," cautioned Bill Ryerson, fellow at the Post-Carbon Institute and president of Population Media Center and The Population Institute. "It must be a catalyst for people, leaders and advocates regarding the steps we need to take to achieve sustainability."

Sustainability is key, because even rats can tell you that our expansive, singular planet has more than enough actual room to fit the 10 billion and more that humanity is expected to create over the next few centuries. After all, the definition of overpopulation has less to do with raw numbers of people than their relationship with the planet's sustainable resources. Yet population control remains a controversial topic, for everyone from real-time worriers like the Roman Catholic church and anti-choice Republicans to sci-fi dystopias like Logan's Run and In Time, which topically opened the Friday before Earth was scheduled to reach its seven-billion benchmark.

"The world is much more interconnected now than any time in history," Center for Environment & Population director Vicky Markham told AlterNet. "This is not only because of technology, but also because our per-capita energy, water, land, forest and other natural resource use is linked around the globe. America is particularly important: While we represent just five percent of the global population, we contribute 25 percent of the planet's energy use and carbon dioxide emissions. So our role in global climate change is disproportionately large; so should be our responsibilities for curbing it."