Posts Tagged ‘Population’

Comments Off on Annual Polar Bear Migration Under Way : How It Works and How Climate Change Could Be Impacting It

Melting sea ice means big changes for the world’s 20,000 polar bears. (A polar bear watches over two cubs in Hudson Bay, near the town of Churchill, Manitoba) Photograph by David Jenkins/Robert Harding/Corbis In the past month, hundreds of polar bears have strolled past a small town in Canada. It’s part of their annual migration […]

Comments Off on Did a Mega-Flood Doom Ancient American City of Cahokia?

(Clues found near the site of Cahokia (above) indicated that a flood occurred at the height of the city’s population and power.) Photograph by Ira Block, National Geographic. One thousand years ago, on a floodplain of the Mississippi River near modern-day St. Louis, the massive Native American city known today as Cahokia sprang suddenly into […]