Saturday, April 4, 2009

More Scientists Notice the Pace of Arctic Climate Change

One of the biases you will see in science is a tendency to believe that things are not changing. There would be no science unless we could pin down principles and characteristics that don’t change, so it’s understandable that science would seek those out. At the same time, the built-in skepticism of science often turns into a skepticism of change, in which scientists may continue to insist that things are not changing until there is overwhelming evidence that change is occurring.

All this is frustrating to those of us who are trying to get science to recognize a change that is taking place, such as the change in Arctic climate reflected in the disappearance of the Arctic ice cap. It is easy enough for someone like me to point to one event after another and say, “That never happened before! That never happened before!” Scientists need good, clean data, and often lots of it, before they can prove anything.

In the Arctic, scientists have long since proved the “Arctic ice cap” of mid-20th century textbooks does not currently exist. But that’s not the same as proving that the ice cap melted. Maybe the textbooks were wrong. There was nevertheless enough solid data by about 1997 to create a consensus that the Arctic climate is changing and the ice is melting, but not nearly enough to describe the pace of change. How long would it take for the Arctic ice to melt? Some thought 10,000 years; others, 250.

That recognition is more progress than it sounds like, because once you establish the existence of a trend, it’s considered fair game to use any available data to make the best guess you can about the pace of change. The stories that are coming back from visits to the Arctic Ocean suggest that the change is happening rapidly, and more and more data is being collected.

One reason scientists are starting to acknowledge the pace of change in the Arctic is that the data is showing that the more cautious climate-change models are wrong. One model of Arctic climate predicted a five-degree increase in fall Arctic surface temperatures by 2070. Then data came in that showed that the predicted five-degree increase had already occurred by 2008. Does that mean the Arctic ice is melting 62 years sooner than they thought? Well, maybe so — it’s hard to argue with hard data.

You can watch the extent of Arctic sea ice day by day and see history taking place. This spring the ice is melting rapidly and is closer to the record minimum track of two years ago than to the long-term average. Will Arctic sea ice set a new record minimum this year? There have been several new record lows in recent years, and with the ice thinning dramatically last year, a new record low this year seems more likely than not.

To the public, television is the ultimate proof, and most people won’t be completely convinced that the ice cap is gone till they see the live pictures on CNN of Richard Branson’s yacht at the North Pole. That may still be a few years away, but commercial shippers are hoping for the first trans-Arctic commercial freight traffic this summer, and that too would be a change that would be hard to argue with.

With all the focus on sea ice, it is easy to forget that the most compelling evidence of climate change is on land. The loss of permafrost has been affecting towns across Alaska and northern Canada since at least the early 1990s. It’s a change you can see, it doesn’t depend on the precise calibration of anything, it’s a permanent change, and it affects everything else.