Tide gauge-based sea level variations since 1950 along the Norwegian and Russian coasts of the Arctic Ocean: Contribution of the steric and mass components

Abstract. The Arctic Ocean is at the frontier of the fast changing climate in the northern latitudes. As the first study, we assess the different mass and steric components of the observed sea level trend from both absolute sea level (ASL) from altimetry and tide gauges, without using gravimetric observations from GRACE. This approach permits a longer time series and avoids problems with errors from leakage effects in GRACE-products. ASL is equal to mass-driven sea level added with steric sea level, while tide gauge based sea level are also corrected with novel estimates of vertical land movement. Calculations of the mass component from present-day deglaciation, shows that deglaciation rises Arctic sea level with more than 1 mm y−1, while the steric contribution is between −5 and 15 mm y−1 with large spatial variability, with the halosteric signal dominating the pattern. A dynamic mass contribution is derived from the Estimating Circulation and Climate of the Oceans (ECCO)-model (version 4 release 4), which varies between −1 and 2 mm y−1. The combined mass and steric product agrees (within uncertainty) with ASL-trends observed from altimetry in 99 % of the Arctic, although large uncertainties originate from poor data coverage in the steric data and large variability in the dynamic product. A comparison with ASL trends observed at tide gauges agrees with mass+steric at 11 of 12 tide gauge sites.

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The Younger Dryas and the Sea of Ancient Ice

Quaternary Research ◽

10.1016/j.yqres.2008.03.002 ◽

2008 ◽

Vol 70 (1) ◽

pp. 1-10 ◽

Cited By ~ 81

Author(s):

Raymond S. Bradley ◽

John H. England

Keyword(s):

Sea Ice ◽

Arctic Ocean ◽

Sea Level ◽

Barents Sea ◽

Younger Dryas ◽

Arctic Basin ◽

Arctic Sea Ice ◽

The Arctic ◽

Floating Body ◽

The Arctic Ocean

AbstractWe propose that prior to the Younger Dryas period, the Arctic Ocean supported extremely thick multi-year fast ice overlain by superimposed ice and firn. We re-introduce the historical term paleocrystic ice to describe this. The ice was independent of continental (glacier) ice and formed a massive floating body trapped within the almost closed Arctic Basin, when sea-level was lower during the last glacial maximum. As sea-level rose and the Barents Sea Shelf became deglaciated, the volume of warm Atlantic water entering the Arctic Ocean increased, as did the corresponding egress, driving the paleocrystic ice towards Fram Strait. New evidence shows that Bering Strait was resubmerged around the same time, providing further dynamical forcing of the ice as the Transpolar Drift became established. Additional freshwater entered the Arctic Basin from Siberia and North America, from proglacial lakes and meltwater derived from the Laurentide Ice Sheet. Collectively, these forces drove large volumes of thick paleocrystic ice and relatively fresh water from the Arctic Ocean into the Greenland Sea, shutting down deepwater formation and creating conditions conducive for extensive sea-ice to form and persist as far south as 60°N. We propose that the forcing responsible for the Younger Dryas cold episode was thus the result of extremely thick sea-ice being driven from the Arctic Ocean, dampening or shutting off the thermohaline circulation, as sea-level rose and Atlantic and Pacific waters entered the Arctic Basin. This hypothesis focuses attention on the potential role of Arctic sea-ice in causing the Younger Dryas episode, but does not preclude other factors that may also have played a role.

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