The long, frigid Arctic autumn and winter began late last week—and the shrinking sea ice has begun to expand anew. That's good news for starving polar bears waiting for the ice to come in so they can hunt. But the dwindling ice pack—courtesy of global warming—bodes ill for Earth's future.

"The continued drastic melting of the Arctic sea ice is a disaster for the polar bear and a harbinger of what's to come for the rest of the world if we don't reduce greenhouse gas emissions," says Kassie Siegel, climate program director at the Center for Biological Diversity, who led the charge to list the polar bear as an endangered species.

For the second year in a row, the fabled Northwest Passage has opened in the Arctic—thanks to a sea-ice melt that has already shrunk the polar cap to the second smallest extent ever recorded. And with a few more weeks to go in the summer thaw season, 2008 could surpass 2007 as the smallest amount of sea ice on record, according to the National Snow and Ice Data Center (NSIDC).

This year's record-breaking melt was, to some extent, set up by the 2007 season—also a record-breaker. More open ocean means more trapped heat in the water, which means that thinner ice forms during the long Arctic winter. Thinner ice melts more readily when temperatures rise. So, despite a relatively cool summer this year, the sea ice is just melting away.

The thawing of the fabled Northwest Passage on Canada's north coast isn't just an opportunity for humans to cut shipping times between Asia, Europe and North America—or squabble over oil. It's also an opportunity for the tough shellfish species that thrive in the northern Pacific to colonize the gentler environs of the northern Atlantic, according to new research in Science.

Last year—thanks to global warming—said passage cleared for the first time in recorded history as the ice that covers the Arctic Ocean dwindled to a record minimum. This year is shaping up to be another low and scientists project that the Arctic could be ice free by the summer of 2050--or sooner.

Warmer waters (and water that is not beneath an ice sheet) means plankton—food for these mollusks—enabling them to slowly spread across the Arctic Ocean and into the Atlantic. They've done it before. The fossil record shows that a similar invasion of clams, oysters, snails and slugs took place in the Pliocene era (roughly 3.5 million years ago)—the last time the Arctic was ice free.

It looks as though global warming will cut short a study of… global warming.

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That’s what happens when your lab sits on a melting ice floe. Adrift on ice in the Arctic Ocean, 21 Russian scientists (and two dogs) will need an early rescue thanks to global warming. The ice chunk supporting North Pole-35—a project designed to study Arctic flora and fauna, environmental conditions and even geography—has dwindled from 3 square miles to just 0.7 square miles.

That's still 2 million square feet, but it brings the floe's edge too close to the expedition's huts and equipment for comfort. So instead of abandoning the floe in September, as planned, scientists will climb aboard a research vessel towed by the nuclear ice-breaker Arktika in coming days. Just when depends on ice conditions, of course.