A younger, thinner Arctic ice cover: Increased potential for rapid, extensive sea‐ice loss

Satellite‐derived estimates of sea‐ice age and thickness are combined to produce a proxy ice thickness record for 1982 to the present. These data show that in addition to the well‐documented loss of perennial ice cover as a whole, the amount of oldest and thickest ice within the remaining multiyear ice pack has declined significantly. The oldest ice types have essentially disappeared, and 58% of the multiyear ice now consists of relatively young 2‐ and 3‐year‐old ice compared to 35% in the mid‐1980s. Ice coverage in summer 2007 reached a record minimum, with ice extent declining by 42% compared to conditions in the 1980s. The much‐reduced extent of the oldest and thickest ice, in combination with other factors…