Nature: Human Warming Now Pushing Entire Greenland Ice Sheet into the Ocean [View all]

[GliderGuider]

Nature: Human Warming Now Pushing Entire Greenland Ice Sheet into the Ocean

Greenland — a vast store of ice three kilometers tall at its center and the final remnant of the Northern Hemisphere’s great glaciers of the last ice age has now begun what is likely an unstoppable rush to the sea. For according to a new report in Nature Climate Change, the last stable region of glacial ice along the Greenland coastline is now accelerating through one of the ice sheet’s largest and deepest outlets — the Zachariae Ice Stream.

Throughout the 1990s and into the early 2000s, both warmer air and ocean water temperatures at the margins of Greenland began to speed up and destabilize glaciers all along Greenland’s southern, eastern and western coasts. But the northern glaciers remained relatively stalwart, continuing the rate of seaward motion observed over previous decades.

Then, starting in 2003, something ominous began to happen. A combination of sea ice loss, warming air and ocean temperatures began to affect the northern edge of the great ice sheet. Its speed of forward motion through its outlet bays began to increase. By 2012, the great glaciers were dumping 10-20 billion tons, or roughly 10-20 cubic kilometers of ice into the ocean every single year. In just nine years the Zachariae Ice Stream had retreated a total of 20 kilometers toward the heart of Greenland. By comparison, the Jakobshavn Ice Stream, known to be Greenland’s fastest and located in South Greenland, has retreated 35 kilometers over the past 150 years.

The initiation of the great Zachariae Ice Stream’s destabilization is ominous for a number of reasons. First, it means the entire Greenland Ice Sheet has, as of the early 2000s, begun a plunge into the ocean that is likely unstoppable. For once the great and massive glaciers of Greenland start to move, gravitational inertia sets in and even a radical cooling of the climate may not halt the surge. Furthermore, the Zachariae Ice Stream drains 16 percent of the entire Greenland ice sheet alone. And finally, Zachariae stretches deep into the heart of Greenland, extending seven hundred kilometers inland and taking hold of Greenland’s massive central glaciers in its now accelerating ocean-ward draw.

Tick, tick, tick...