'Tis the season in the Arctic when the sun disappears below the horizon and twilight replaces daylight. Temperatures drop and ice that melted throughout the Arctic summer begins to cover the world's northernmost ocean again. Scientists have used satellite pictures since 1979 to map the extent of such ice at its minimum, and the picture this year isn't pretty. Covering 1.59 million square miles (4.12 million square kilometers), this summer's sea ice shattered the previous record for the smallest ice cap of 2.05 million square miles (5.31 million square kilometers) in 2005—a further loss of sea ice area equivalent to the states of California and Texas combined.

"The sea ice cover this year has reached a new record low," says Mark Serreze, senior research scientist at the U.S. National Snow and Ice Data Center in Boulder, Colo. "It's not just that we beat the old record, we annihilated it."

As a result of atmospheric patterns that both warmed the air and reduced cloud cover as well as increased residual heat in newly exposed ocean waters, such melting helped open the fabled Northwest Passage for the first time [see photo] this summer and presaged tough times for polar bears and other Arctic animals that rely on sea ice to survive, according to the U.S. Geological Survey. Such precipitous loss of ice cover far outpaces anything climate models or scientists have predicted.

This new record low continues the trend of steadily shrinking summer sea ice. "We're already set up for a big loss next year," Serreze notes. "We've got so much open water in the Arctic right now that has absorbed so much energy over the summer that the ocean has warmed. The ice that grows back this autumn will be thin."

In fact, a German expedition on the icebreaker Polarstern has revealed that existing Arctic sea ice in the center of the ice cap is only about three feet (one meter) thick, 50 percent thinner than it was just six years ago. As a result, more melt water is mixing with the salty seawater and pulses of warmer Atlantic seawater have intruded into the Arctic Ocean.

Whereas the South Pole remains protected by differing geographic, atmospheric and oceanic conditions, the North Pole is undergoing rapid change not seen in at least 6,000 years and perhaps as much as 125,000 years, and which may spread to lower latitudes. "It is reasonable to think that if you lose the sea ice cover that is going to have an impact elsewhere, in the midlatitudes," Serreze says. Some modeling studies of such effects have suggested drought in the western U.S. or changes in precipitation patterns across Europe.

Serreze expects the ice will bounce back somewhat next year, if only because he cannot imagine it shrinking any more so swiftly. But ice-free summers in the Arctic may become the norm in the near future. "At this point, I'd say the year 2030 is not unreasonable" for a summer without sea ice in the Arctic, Serreze says. "Within our lifetimes and certainly within our children's lifetimes."

When that occurs, the Arctic Ocean may become a spooky, foggy place, haunted by diminished populations of spectrally thin polar bears clinging to life in residual habitat. "It's going to be a different world," Serreze notes. "The observed rates of change have far outstripped what we projected."