More melting mayhem

Yet more evidence that the Arctic ice cap is disappearing at (yes, here comes that word again) alarming rates. This time the harbinger of bad news is William L. Chapman of the University of Illinois Urbana-Champaign.

Today, the Northern Hemisphere sea ice area broke the record for the lowest recorded ice area in recorded history. The new record came a full month before the historic summer minimum typically occurs. There is still a month or more of melt likely this year. It is therefore almost certain that the previous 2005 record will be annihilated by the final 2007 annual minima closer to the end of this summer.

Andrew Revkin, who seems to have assumed the mantle of full-time climate reporter for the New York Times, reports that there is a little bit of friendly disagreement between Chapman and Mark Serreze, of the National Snow and Ice Data Center in Boulder. But the debate evokes the marginal disagreement between those who think 1998 was the warmest year on record or those like 2005. In the end they're just splitting hairs. As Chapman notes on his website:

Regardless of these differences, the rapid rate of sea ice melt this summer, along with the current negative sea ice anomalies almost guarantees a record Northern Hemisphere summer sea ice minimum this summer, by any metric.

And Revkin writes that

it was close even by the center's calculations, he said, adding that it is almost certain that by September, there will be more open water in the Arctic than has been seen for a long time. Ice experts at NASA and the University of Washington echoed his assessment.

Here's one of the more dramatic graphical illustrations, using sea ice area anomaly as the metric. In other words -- the difference between historic norms and what we're seeing now (click on it for full size):

For those who haven't been following the science of melting ice caps, read this and this.