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

[1] 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.