The area covered by sea ice in the Arctic has shrunk to its lowest level since satellite measurements began nearly 30 years ago, opening up the Northwest Passage â€“ a long-sought short cut between Europe and Asia that has been historically impassable.

In the mosaic image above, created from nearly 200 images acquired in early September 2007 by the Advanced Synthetic Aperture Radar (ASAR) instrument aboard ESAâ€™s Envisat satellite, the dark gray color represents the ice-free areas while green represents areas with sea ice.

Leif Toudal Pedersen from the Danish National Space Centre said: “We have seen the ice-covered area drop to just around 3 million sq km which is about 1 million sq km less than the previous minima of 2005 and 2006. There has been a reduction of the ice cover over the last 10 years of about 100 000 sq km per year on average, so a drop of 1 million sq km in just one year is extreme. To give you an idea of how big 1 million sq km is that is about 386,000 sq miles, or 1.5 times the size of Texas.

With melting this year 10 times the average are we experiencing the tipping point? The tipping point would be when there is enough dark ocean water not covered with white reflective ice that the amount of heat absorbed would make it impossible for ice to reform. It is extremely hard to calculate just when this point will happen, but we can imagine what the results of such a scenario would be.

The first thing we would notice is a rapid, and out of control melting (see above), this would be because as more ice melts, more heat is absorbed, which melts more ice, which allows more heat to be absorbed, which melts more…you get the idea. The second thing we would notice is that the ice that did form this winter would not extend as far as previous years (we will have to wait to see this data as the ice usually continues to melt until mid/late September). If the ice does fail to recover this winter it means that all winter long the water exposed to the sun will be kept at a higher temperature than it normally would and next summer the ice will melt that much faster.

“The strong reduction in just one year certainly raises flags that the ice (in summer) may disappear much sooner than expected and that we urgently need to understand better the processes involved.”

Arctic sea ice naturally extends its surface coverage each northern winter and recedes each northern summer, but the rate of overall loss since 1978 when satellite records began has accelerated.

The most direct route of the Northwest Passage (highlighted in the top mosaic by an orange line) across northern Canada is shown fully navigable, while the Northeast Passage (blue line) along the Siberian coast remains only partially blocked. To date, the Northwest Passage has been predicted to remain closed even during reduced ice cover by multi-year ice pack â€“ sea ice that survives one or more summers. However, according to Pedersen, this yearâ€™s extreme event has shown the passage may well open sooner than expected.

The previous record low was in 2005 when the Arctic area covered by sea ice was just 4 million sq km. Even then, the most direct Northwest Passage did not fully open.

The Polar Regions are very sensitive indicators of climate change. The UNâ€™s Intergovernmental Panel on Climate Change showed these regions are highly vulnerable to rising temperatures and predicted the Arctic would be virtually ice free by the summer of 2070. Still other scientists predict it could become ice free as early as 2040 due to rising temperatures and sea ice decline.





click for larger animation above.

The prospect of a warm arctic, is in short not a good one. Not good for polar bears, not good for the people who live in the arctic, and even though they think it would be a gold rush, not good for industrialized countries either.

If this is the tipping point, it might be a little late to do much. But if this is just a small taste of things to come, well we still have some time. Quick direct action to lower CO2 emissions will make progress towards healing this problem. Things are starting to get pretty serious. I wonder will we start to act?