WASHINGTON — An iceberg 47 miles long and 4.6 miles across has broken off the Ross Ice Shelf in the Antarctic, the National Ice Center reported Thursday.
The giant sheet of glacial ice and snow was named C-18, meaning that it's the 18th iceberg to be tracked in that section of Antarctica since 1976, when record keeping began.
The iceberg, floating close to the ice shelf, is not considered a hazard to navigation. It was spotted on satellite images.
The discovery comes just under a month after a much larger iceberg — 40 miles by 53 miles — broke away from another part of Antarctica. That iceberg is known as B-22.
Also in March, a large floating ice shelf in Antarctica collapsed. The 1,250-square-mile section of the Larsen Ice Shelf collapsed during a five-week period that ended March 7. It splintered into a plume of drifting icebergs.
Meanwhile, however, new measurements indicate the ice in parts of Antarctica is thickening, reversing earlier estimates that the sheet was melting.
Scientists reported in January that new flow measurements for the Ross ice streams indicate that movement of some of the ice streams has slowed or halted, allowing the ice to thicken.
Researchers don't know if the thickening is merely part of some short-term fluctuation or represents a reversal of the long retreat of the ice.
That report, in the journal Science, came less than a week after a paper in Nature reported that Antarctica's harsh desert valleys — long considered a bellwether for global climate change — have grown cooler since the mid-1980s.
The National Ice Center provides worldwide ice analyses and tracking to assist the military and private shippers.
It is a joint operation of the Navy, National Oceanic and Atmospheric Administration and Coast Guard.
On the Net: Satellite image: www.natice.noaa.gov/c18.jpg
