[UPDATE, 7/14: A remarkable animation depicting the pulsing flow of Arctic sea ice over a stretch of years moved to the “jump” page because it was slowing the loading of Dot Earth for some users.]

The Drudgeosphere was all pumped up today about the “shock claim” in the (UK) Independent that the sea ice that normally persists year-round at the North Pole (I stood on it in March, 2003) will be replaced by open water later this summer.

Given the unpredictable short-term dynamics up there, which make the ice subject to vagaries of Siberian winds and a mix of currents, a lot of polar ice experts tell me it’s pretty much impossible to make such a prediction with high confidence. In fact, the Independent’s story — the opening sentences and headline at least — go way beyond what Mark Serreze of the National Snow and Ice Data Center tells the reporter. As early as May, ice experts were putting good odds on having open water at the North Pole. [UPDATE 11 p.m.: Gavin Schmidt of Realclimate.org muses on why the media hyperventilate over polar non-news developments.]

One way or the other, it’s clear that, by the end of the 1990s, the veneer of ice on the Arctic Ocean had shifted to a far more tenuous state, with ever less thick, years-old ice like the floes I camped on when I went with the team setting up the annual North Pole Environmental Observatory. The animation above shows that the ice was flushed out, not melted.

Most of the seasoned Arctic ice experts I’ve canvassed for recent stories see the region exhibiting a mix of natural variability in the ice (like the flushing process) and a long-term trend toward less of it in summer, and more of it being fresh-made each season, and thus thin and easy to melt. Most also are convinced the change is now at least partly driven by human-caused global warming.

Their various projections are laid out in monthly Sea Ice Outlook reports. Right now the odds are essentially even on a 2008 match for the dramatic ice loss last year.

Here’s what trends looked like leading to last year’s remarkable ice vanishing act:

Many foes of greenhouse-gas restrictions and skeptics on the strength of climate science have pointed out that the world’s total sea-ice area hasn’t changed appreciably when you add up the ice in the Arctic and the sheath of sea ice that annually forms in winter around Antarctica (but disappears in austral summers). The Antarctic sea ice (distinct from the massive ice shelves fringing the continent and ice sheets inland) has, in fact, been expanding in recent years. You can compare the differences by clicking here for Arctic and Antarctic trends.

But scientists studying trends at both poles say there is nothing inconsistent with the intensifying greenhouse effect. William Chapman, who maintains the helpful Cryosphere Today Web site at the University of Illinois, Urbana-Champaign, sent me an email this morning reminding me of a 2005 study that projects more Antarctic sea ice (by volume) in a warming world.

“Yes, sea ice seems to behaving as the consensus of the climate models have been projecting – more rapid and larger response in the northern high latitudes than anywhere else, flat to possible increase in [southern hemisphere] sea ice as warming takes hold,” he wrote.

Here’s where the extent of sea ice in the Arctic stands now in relation to the average tracked between 1979 and 2000, and the remarkable ice loss in 2007: