for National Geographic News
For decades the northern Japanese island of Hokkaido has attracted tourists hoping to step out onto drifting slabs of the world's southernmost Arctic sea ice.
Free-floating pieces of ice that form each winter in the Sea of Okhotsk travel about 620 miles (1,000 kilometers) to Hokkaido's Shiretoko Peninsula. The ice, which normally lingers near the coast for up to four months, is key to the region's rich biodiversity, including many rare seabirds and marine mammals. (See a map of the region.)
In recent years, however, the peninsula has seen noticeably less drift ice, raising fears that global warming is to blame.
Arctic sea ice overall has been disappearing much faster than initially predicted, with some experts saying that the region's summer ice could be gone within five years.
Over the ten years leading up to 2007, the amount of sea ice forming in the Sea of Okhotsk shrank by 3.6 percent, according to the Japan Meteorological Agency.
And in 2004 the Shiretoko town of Abashiri had just 54 days of drift ice—the second shortest period of ice there since 1946, when recordkeeping began.
"If you just look at the last five years of data, the amount of drift ice is decreasing," said Takashi Yamamoto, director of a tour company that has organized icebreaker trips from Abashiri since 1991.
"It's a headache for us," he said. "If this continues, we are going to be in trouble ten years from now. Perhaps we need to think about a different kind of business."
Between January and April tourists flock to Abashiri and other towns along the peninsula's coast to see and sometimes step out onto the Arctic drift ice.
Where it reaches the coast, the sea ice is thick enough for dry suit-clad visitors to scramble onto some of the jagged chunks.
Data from the Abashiri Meteorological Observatory, near the base of the peninsula, show that drift ice has approached the Abashiri coast for an average of 87 days each year since 1971.
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