The world's population has just hit 7 billion people and continues to grow. Population experts are concerned about the rise in consumption that will accompany the increase in people. One California home builder, ZETA Communities, designs and builds small, highly energy-efficient homes.

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itoggle caption Zeta Communities

Lujiazui, Shanghai's financial district, includes the world's third- and sixth-tallest buildings. The city's population is 23 million.

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The National Audubon Society considers fall leaves to be "natural vitamins" to use in yards.

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To feed China's insatiable demand for coal, U.S. companies are trying to sell and ship the lucrative commodity to the Asian market from new West Coast ports. Above, the cooling towers of a coal-fired power plant are seen on the outskirts of Beijing.

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A researcher who wrote a famous report about dead polar bears was asked to take a polygraph test by a federal agent who has been investigating allegations of scientific misconduct. Above, a polar bear rests with her cubs on pack ice in the Beaufort Sea in northern Alaska.

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Bellingham, Wash., a progressive college town of 81,000, could soon be home to a new coal terminal. Developers want to ship the lucrative commodity to China, but some locals are worried about the potential environmental impacts.

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