Contribution of melt in the Beaufort Sea to the decline in Arctic multiyear sea ice coverage: 1993–2009

Abstract

For the summers of 1993 through 2009, we estimate the loss of multiyear sea ice (MYI) area in the Beaufort Sea due to melt. Parcels of MYI in April are traced into the Beaufort Sea where they melt as the ice edge retreats. Net loss of area (with fractional MYI coverage >50%) over the 17‐year period is ∼900 × 103 km2. Three‐quarters of that area, ∼10% of the area of the Arctic Ocean, was lost after 2000. There is a clear positive trend in the record, with a distinct peak of 213 × 103 km2 in 2008; this is twice the summer outflow at the Fram Strait that year. The net melt area of 490 × 103 km2 between 2005 and 2008 accounts for nearly 32% of the net loss of 1.54 × 106 km2 of Arctic Ocean MYI coverage over the same period. Volume loss, for the years with ICESat thickness (2004–2009), is highest at 473 km3 in 2008 followed by 320 km3 in 2007. Net loss in MYI volume for the six summers is ∼1400 km3. This is ∼20% of the loss in MYI volume of 6300 km3 during 2004–2008. This adds to the freshwater content of the Arctic Ocean and locally to the freshening of the Beaufort Gyre.