August 13, 2008—Visitors to Japan's northern island of Hokkaido venture onto drift ice near the coast of Shiretoko Peninsula. These free-floating pieces of ice, which annually travel about 620 miles (1,000 kilometers) from the Sea of Okhotsk, are the world's southernmost Arctic sea ice.

In recent years the amount of drift ice reaching Shiretoko has decreased noticeably, raising fears global warming will affect the local ecosystem and endanger winter tourism. (Read the full story.)

Tatsuya Fujisaki, who leads walking tours onto the ice, said his experience is in line with data indicating 2006 and 2007 were unusually bad years.

"There was a lot of ice this year, but the ice was thinner than usual," he said. "You can fall through it easily, and the slightest wind will shift the ice."

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