Arctic sea ice has reached its peak extent for this winter, clocking in as the joint-smallest in a satellite record going back almost half a century. Provisional data from the US National Snow and Ice Data Center (NSIDC) shows that sea ice extent peaked at 14.29m square kilometres (km2) on 15 March. This is slightly smaller than the previous record for the annual maximum – set just last year – but it counts as a statistical tie, the NSIDC says. The annual maximum is a key marker in a cycle that sees sea ice extent grow through the cold, dark winter, before melting in spring and summer to a yearly minimum. The joint record marks a “very alarming” winter for Arctic sea ice, Dr Zack Labe – a scientist at Climate Central – tells Carbon Brief. And there is more “grim news”, Labe says, as the thickness of the ice is near record lows – meaning that Arctic sea ice is “entering late winter in one of its weakest states in the satellite record”. ‘Unusually warm’ The past six months has seen Arctic sea ice extent “at record or near-record lows, alongside unusually warm conditions” across much of the region, says Dr Lettie Roach, a polar climate scientist at the Alfred Wegener Institute. These go “hand in hand”, Roach tells Carbon Brief, as “warmer air and ocean temperatures help melt the ice and with less ice, the ocean absorbs more heat, which further speeds up warming”. The chart below shows…
