The exchange of staff and equipment is taking place on foot, with snowmobiles and with snowcats hauling heavily laden sledges. On board Polarstern and in the Ice Camp, the new expedition members are being instructed on various tasks by their predecessors. Extreme caution is the prime rule, especially when working on the ice, where the wind-chill temperature can now reach 58 degrees below zero Celsius. Thanks to these extreme temperatures, only a day after her arrival, the channel of open water left behind by Kapitan Dranitsyn had refrozen so rapidly and intensively that the researchers could walk on it. The temperatures also pose a problem when it comes to transferring provisions; for example, fresh produce has to be transported in heated containers. It’s still too soon to say how long the transfer of crew and equipment will take to complete, partly because the two ships’ cranes only work very slowly in the frigid conditions.
Shortly before beginning the journey home, Prof Christian Haas from the Alfred Wegener Institute, Chief Scientist for the second leg, took stock of the situation. According to the sea-ice expert, “Over the past few months, we’ve been able to observe winter at the North Pole more consistently and precisely than ever before. The ice thickness has doubled to an average of 160 centimetres since December, which corresponds to a growth rate of roughly ten centimetres per week.”
In addition, with the aid of helicopter laser-scanner readings, Polarstern’s radar system, and buoys, the researchers were able to observe how the ice deformed, and channels opened and closed again. Thanks to the warming of the Arctic Ocean, smaller and thinner ice floes are becoming more common. Driven by the wind, they can collide and overlap, producing pack ice hummocks up to four metres tall. Since a great deal of their mass lies underwater, some hummocks are 20 to 30 metres thick – a phenomenon that now represents a challenge for the resupply icebreakers.