Scientists say that arctic sea ice at its minimum extent — that is, the north pole’s icecap at the moment when there has been as much summer melting as there is going to be in a given cycle –has been declining at a rate of 13.1% per decade.
The surface of a patch of white ice reflects Earth-bound sunlight upward, back into space. This is known as albedo. There is an ice-albedo feedback cycle, such that the reduction of the arctic sea ice over time has allowed more of the sun’s energy to enter the darker-colored water, which in turn has helped melt the ice more quickly.
Why is this important? One reason for concern is simply that there is a huge ecosystem in the arctic that depends upon the annual recurrence of that ice. Most obviously, such animals as Arctic Foxes, seals, and polar bears lose their habitat.
Less obviously, the regular freezing and melting of polar cap ice creates a cycle within the water below, as water near the surface becomes saltier during the freeze-up and sinks into the depths and water in the depths according moves upward to match this. That water from the depths is nutrient rich, and that underwrites an aquatic ecosystem.
Strange New Worlds:
According to Dr. Rachel Tilling, a sea-ice expert at the University of Maryland, “Our planet is this huge, interconnected place, and the atmosphere is connected across it. The Arctic is changing so rapidly, that we don’t even know yet exactly how the changes there are going to impact us. All we know is that they will.”