Following last year’s record low sea ice coverage in the Arctic, NASA data released today shows a slight increase in square mile coverage, which would be considered a good thing were it not for something else they discovered: the area of Arctic perennial sea ice actually decreased. Perennial sea ice is the thicker, longer-lived ice that is present throughout the year. And according to scientists that makes this particular ice vulnerable to further melting this coming summer.

For the past couple of years scientists have been blaming the ice melt on human-caused climate change saying sea ice has shrunk precipitously in the past decade. But last summer, the melting intensified and the ice shrank to an area 27% smaller than the previous record. Overall ice coverage this winter grew by 4% to 5.8 million square miles. Still, according to NASA scientist Josefino Comiso, ice coverage area is still below the long-term average level for this time of year.

“It could be compared to a building in a movie: it looks OK, you see a building, but in fact it’s a set, and behind the facade there is nothing,” said Walter Meier, of the National Snow and Ice Data Center at the University of Colorado in Boulder.

Left: February ice age distribution in the Arctic during normal conditions (1985-2000 average). Right: February 2008 Arctic ice age distribution. The ice in the Arctic is much younger than normal, with vast regions now covered by first-year ice (ice that has formed since last summer’s melt) and much less area covered by multiyear ice (ice that has survived at least one melt season). Ice that is 6 years old or older shows an even more dramatic decrease in 2008 compared to average conditions. Ice age is a good indicator of general ice thickness, with older ice thicker on average than younger ice. First-year ice generally ranges between about 3-5 feet thick, while multiyear ice averages about 8-10 feet; old ice that has survived several melt seasons can easily be 12-15 feet thick. > High resolution image Credit: NSIDC, Courtesy S. Drobot, University of Colorado, Boulder

So, why does this matter to us? “What happens there, matters here,” according to Waleed Abdalati, head of ice studies at NASA Goddard Space Flight Center in Greenbelt, Maryland. “Climate for the period of human record has depended on the ice being there.”

The amount of summer Arctic sea ice matters because it acts as an air conditioner for the planet’s climate. It is connected intimately with global weather patterns and affects temperature, and wind and oceanic currents. There is some concern also that there could be an adverse affect on the Ocean Convery Belt.

But what is important to take away from this is that more than 70% of the new sea ice this year is thin and salty and adds no additional volume to the perennial ice and this, combined with the effects of global warming, have resulted in a net loss in ice that survives the summer season.

In fact, as Meier explains, the Arctic has lost more than half of its perennial ice since 1980. And, to make matters worse, three quarters of its “tough as nails” ice 6 years or older,  has melted. To put the amount of sea ice loss into perspective, the area lost, he says, is the size of Texas - times two!

Scientists suspect that this can only mean one thing: when the temperature comes up again this coming summer, we can expect plenty of melting. “We’re in for a world of hurt this summer,” Mark Serneze, NSIDC senior scientist, told the Associated Press today.