Arctic sea ice extent image for August 24, 2010, as compiled by The University of Illinois Cryosphere
For the fourth year in a row, and for the fourth time in recorded history, the Northwest passage is completely open. For only the third time, both the Northwest and Northeast passage (north of Russia) are open. If you had a fast enough boat you could race right around the North Pole and Greenland.
Jeff Masters explains why in his Wunderblog:
This year, Canada experienced its warmest winter in history, and record warm temperatures were observed during spring over the Western Canadian Arctic. Spring 2010 was the warmest in the region since 1948; some regions of the Western Canadian Arctic were more than 6°C (11°F) above average. These warm conditions helped break the ice up early in the Northwest Passage. Warm conditions continued this summer over both the Northwest and Northeast Passages, with temperatures averaging 1 - 2°C above average over the majority of the region. As observed in previous years, contributing to this year's melt was the presence of much warmer than average ocean waters invading the Arctic from both the Pacific and Atlantic Oceans, and the deposition of black soot on the ice, which absorbs sunlight and heats up the ice.
It took Roald Amundsen three years to sail through the passage, dodging pack ice and getting frozen in; now it is smooth sailing. More at wunderground, via
Northwest Passage opens for 4th year in a row http://j.mp/atJQlt
More on the Northwest Passage, Amundsen and Ice
Global Warming Opens Northwest Passage
Northwest Passage All But Ice-Free