Here’s a update on the mass/volume of article sea ice by by Michael D at Climate Central
The melting season is now fully under way in the high Arctic. Months of relatively warm temperatures and nearly continuous sunshine have taken their toll on the ice that blankets the Arctic Ocean. By mid-September, the sea ice will reach its low point for the year, before starting its annual re-freeze. All of this is normal, but the conditions scientists are seeing this year are anything but normal. “Right now,” said Mark Serreze, director of the National Snow and Ice Data Center in Boulder, Colo., in an interview, “we’re on a record pace for ice loss. If the melt stopped today, we’d have the fourth lowest ice coverage on record.”
Whether this year’s ice loss ends up being worse than the melting in 2007 isn’t the most important question. “What is worrying,” said CryoSat-2 mission scientist Mark Drinkwater in an email, “is the reductions in volume and mass of the sea ice.” The reason is simple: if you’re just looking at how much of the Arctic Ocean is covered by ice, a thin layer is just as good as a thick layer. But a thin layer can melt much more easily, whether buffeted by storms or not, and decades of summer melting have thinned the ice dramatically. “Perhaps most disturbing,” Drinkwater said, “is the fact that current models would appear to be significantly underestimating the true values.”
In short, the new data confirm what scientists have been seeing for several years now: the ice is thinning a lot faster than climate models originally predicted it would, and while no one knows for sure when the first truly ice-free summer in the Arctic Ocean will come, it could plausibly be within years, not decades. That would be terrible news for seals and polar bears, but it could also accelerate the warming of the entire planet.