According to the National Geographic and NASA, an iceberg 350 square miles (907 square kilometers) in area—larger than the five boroughs of New York City combined—is poised to break-off of Antarctica’s fastest-melting glacier. A giant crack 19 miles (30 kilometers) long and up to 260 feet (80 meters) wide has formed in the Pine Island Glacier in West Antarctica. Although it is extremely difficult to predict when the New York City-size ice chunk will split from the glacier, scientists anticipate that it may be within the coming months.
As glaciers flow from the Antarctic continent into the sea, stresses cause the floating ice tongue to break off and form icebergs. This process, called glacial calving, is normal. However, the crack observed in the Pine Island Glacier has caught the eye of scientists not only for its size but for how anomalously far upstream it is occurring. When such rifting begins far upstream, it typically indicates that glacial flow is accelerating, which is of particular concern for the Pine Island Glacier as it is expected to account for a quarter to a third of Antarctica’s total contribution to global sea level rise.
Due to buoyancy effects, glacial ice that already sits in the ocean does not contribute to sea level rise when it splits off to form icebergs that subsequently melt. This is why a melting ice-cube in your drink doesn’t cause the liquid level to rise. But the ice that flows from upstream to replace it—from up on the Antarctic mountains into the sea—will then displace additional ocean water and contribute to sea level rise. So while this New York City-sized iceberg will not cause sea level rise, the fact that this massive crevasse signals accelerating flow—in a glacier that’s already moving at three kilometers (nearly two miles) a year—is especially worrying for the future sea level rise as much more continental ice flows into the sea.
As Ted Scambos of the National Snow and Ice Data Center (NSIDC) in Boulder, Colorado, sums it up, “This glacier is really important.”