Giant Antarctic Iceberg Could Affect Ocean Circulation Patterns

An iceberg 49 miles long and 24 miles wide has broken off from a massive floating ice sheet in East Antarctica, and should the iceberg become wedged near the continent it could affect circulation patterns in the Southern and Atlantic oceans, scientists say. The iceberg, roughly the size of Luxembourg, broke off earlier this month from the 100-mile long Mertz Glacier Tongue, which juts into the Southern Ocean. The iceberg was created, in part, because an even larger iceberg — 60 miles long — rammed into the Mertz Glacier Tongue and dislodged the Luxembourg-sized slab of ice, which is 1,300 feet thick. Both icebergs are now floating next to an extensive area of open water that plays an important part in global ocean circulation patterns. Dense, salty water in this open area slowly sinks to the bottom of the Southern Ocean, then circulates around Antarctica before slowly creeping northward into the Atlantic Ocean, where it eventually rises and plays an important role in Atlantic circulation. Should the icebergs become grounded in the area, as now appears likely, they could change circulation on the ocean’s surface and reduce the volume of so-called Antarctic bottom water heading into the Atlantic, scientists say.