Thursday, August 28, 2008

Arctic Meltdown

This week, scientists at the National Snow and Ice Data Center (NSIDC) announced that the amount of unmelted sea ice in the Arctic has reached the second lowest level since satellite monitoring began 30 years ago, and it may be on a trajectory in the coming weeks to break the record melting that occurred just last year. The revelation comes on the heels of reports earlier this month of polar bears swimming in the open waters off the northwest coast of Alaska. It has long been known that the effects of global warming appear first near the north and south poles, so this news provides a glimpse of what's in store for the rest of the world if we don't begin to change course soon.

On the summer solstice this year, I was on an airplane returning from a two week visit to Denmark -- I purchased carbon offsets for the trip, but the irony of the situation is still tangible. In the middle of the day, I peered out the window to discover that we were flying over the east coast of Greenland. I was encouraged to see that there still seemed to be plenty of sea ice floating around, but the land was littered with cobalt blue melt ponds and the dramatic retreat of the surrounding glaciers was readily apparent from above. Little did I know at the time that only about a third of that sea ice would still be around by the annual low point in mid-September.

Through most of the melting season this year, the total area covered by sea ice in the Arctic has followed roughly the same pattern as observed in 2005, which was previously the second greatest melt in recorded history. But in early August this year, the melting seemed to accelerate -- maybe from all of those flights to China for the Olympics. "We could very well be in that quick slide downwards in terms of passing a tipping point," said Mark Serreze, a senior scientist at the Colorado-based NSIDC. Within the next few weeks as the melting bottoms out, we'll know whether this year's melt breaks the all time record from last year.

Nothing seems to bring this crisis into clearer focus for most people than the plight of the polar bears. Last week an aerial survey of wildlife off the northwest coast of Alaska reported observing 9 polar bears swimming in open waters between 15 and 65 miles offshore. Ironically, the survey was being conducted to prepare for future offshore oil development. Satellite data from the time of the survey showed that the nearest pack ice was about 100 miles from the coast. Polar bears are good swimmers, but they typically only swim distances of 10 to 15 miles. "We have some observations of bears swimming into shore when the sea ice was not visible on the horizon. In some of these cases, the bears arrive so spent energetically, that they literally don't move for a couple days after hitting shore" said Steven Amstrup, senior polar bear scientist for the U.S. Geological Survey in Anchorage. If the changes in Arctic melting were happening more gradually, the polar bears might have time to adapt over many generations. But the unprecedented pace of Arctic warming makes the outlook fairly grim.

The inconvenient truth of the matter is that these events give us a sneak preview of the types of changes we are likely to see at lower latitudes in the coming decades. Only it won't be the polar bears who are struggling to adapt to the new circumstances -- it will be us.