Bremen 2017 – wissenschaftliches Programm
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UP: Fachverband Umweltphysik
UP 3: Kryosphäre
UP 3.2: Vortrag
Dienstag, 14. März 2017, 11:30–11:45, GW2 B3009
Sea ice in the Arctic and Antarctic: recent developments and understanding — •Gunnar Spreen1, Malte Gerken1, Christian Haas2, Stefan Hendricks2, Christian Melsheimer1, Marcel Nicolaus2, Renate Treffeisen1, Justus Notholt1, and Georg Heygster1 — 1University of Bremen — 2Alfred Wegener Institute
Air temperatures in the Arctic are increasing twice as fast as the global mean. As a consequence, the sea ice extent in the Arctic is declining (4%/decade). In summer the decline is strongest. In conjunction also ice thickness, volume, and age decrease while ice drift speed and melt season length increase. 2016 was an extreme year: due to mild temperatures, the winter sea ice maximum in March was the lowest on record. The modal ice thickness was about 35% below average. Due to cooler Arctic summer temperatures, the 2016 sea ice minimum was only second lowest. In autumn above average air temperatures prevailed, causing a late Arctic sea ice freeze up. The average sea ice extent in November 2016 was the lowest November value observed. The average 2016 sea ice extent therefore likely will be the lowest on record. In the Antarctic, sea ice extent is increasing by 1.5%/decade due to more divergent ice dynamics in recent years. In early Antarctic summer 2016, however, the ice extent is much below climatology. While not connected, the low ice extent in Arctic and Antarctic result in a record low worldwide sea ice area. We will present the latest data and discuss causes of the unusual 2016 sea ice situation. Observations from multiple satellite sensors allow a comprehensive analysis by not only taking ice area but also ice thickness and drift into account.