Reflecting on the Melt
NASA notes that the increased summer melt is mirrored by an equally alarming decrease in winter ice extent:
The maximum amount of sea ice in the Arctic winter has fallen by six percent over each of the last two winters, as compared to a loss of merely 1.5 percent per decade on average annually since the earliest satellite monitoring in 1979.The alarming sea ice retreat will not impact sea level (although melting of the Greenland ice sheet certainly will), but it will have many other serious repercussions. Among the most obvious and most frightening is the positive feedback loop that a melting Arctic is expected to create; i.e., as the reflective ice surface is replaced by an energy absorbing ocean surface, melting is liable to beget more melting.
The loss of sea ice is also problematic for many species -- and not just polar bears. As Joey Comiso, a research scientist at NASA's Goddard Space Flight Center, explains:
The seasonal ice regions in the Arctic are among the most biologically productive regions in the world. For example, sea ice provides melt-water in spring that floats because of low density. This melt-water layer is considered by biologists as the ideal layer for phytoplankton growth because it does not sink, and there is plenty of sunlight reaching it to enable photosynthesis. Plankton are at the bottom of the food web. If their concentration goes down, animals at all trophic levels would be deprived of a basic source of food.