Eventually the ice melts or drifts back out to sea, depending on the winds.
The annual drift ice is vital to the pristine ecosystem at Shiretoko, a national park and UNESCO World Heritage site. That's because it carries nutrients that spur phytoplankton growth in the region.
"Plankton are at the base of the food chain," said Masaaki Aota, director of the Okhotsk Sea Ice Museum of Hokkaido.
The productive waters around Shiretoko have traditionally sustained a rich diversity of species, such as Pacific saury, flounder, cod, seals, dolphins, Steller's sea eagles, and white-tailed sea eagles.
But observatory records show that 2003 was the last time Abashiri had more ice than average, and observers say the amount of ice reaching the town has been on a downward trend.
A 2007 report from the Japan Meteorological Agency noted that there is a "gentle tendency toward a decrease in the amount of ice" in the Sea of Okhotsk as a whole.
(Related: "Shrinking Arctic Sea Ice Thinner, More Vulnerable" [March 18, 2008].)
"If the drift ice decreases, so will the amount of plankton," Aota said. "Then there will be an effect on the fish that eat the plankton."
The decrease in drift ice is also having a big impact on local tourism.
Tour director Yamamoto noted that 2008 was a good year, with ice for 86 percent of the tour season. But 2006 and 2007 were the worst years so far: just 12 and 23 days, respectively.
Tatsuya Fujisaki, who runs walking tours onto the drift ice further up the peninsula, confirmed that 2006 and 2007 were unusually bad years.
"There was a lot of ice this year, but the ice was thinner than usual," he added. "You can fall through it easily, and the slightest wind will shift the ice."
Blowing in the Wind
Although Arctic melt is generally considered a result of climate change, experts stop short of directly linking declines in Hokkaido's sea ice to global warming. The peninsula's relatively short data-collection period and a normal variation in the amount of ice makes drawing conclusions difficult, they say.
How much ice arrives in Abashiri, for example, depends on wind patterns, said Keiji Hamada, a scientific officer at the Japan Meteorological Agency.
Southern and western winds tend to push the drift ice away from the coast, so observed decreases in ice reaching the town might not mean there is less drift ice present in the Arctic seas.
"We don't know yet if this is due to global warming," he said.
Still, locals are keen to encourage ecotourism to raise awareness of the possible threat to the drift ice.
The catch is that, like any industry, tourism increases carbon dioxide emissions, which contribute to global warming.
The Okhotsk Sightseeing Federation based in Abashiri has therefore helped set up an organization called the Okhotsk Drift-Ice Trust Movement, with the slogan "Save the Ice, Save the Earth."
The group encourages local hotels to turn heating thermostats down a few degrees. They have also introduced buses that run on used cooking oil, and they ask visitors to bring reusable chopsticks from home.
"We want people who come on holiday to Okhotsk to realize how the drift ice only survives as part of the Earth's sensitive balance," said the federation's secretary-general Masanori Ito.
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