Multi-year study of the carbonate system in the Chukchi Sea with emphasizes on its western part

Abstract:

Variability of the Arctic climate has affected many aspects of the Arctic environment, especially in the Pacific sector of the Arctic. The primary implication is that today’s Arctic cryosphere (glaciers, frozen ground, and sea ice) and biosphere (terrestrial, lacustrine, and marine) are not at steady state; they have changed and will continue to change in response to evolving Arctic climate. Over the decade 2004–2013 environmental changes in the Pacific sector of the Arctic have been dramatic enough to suggest that a ‘new normal’ climate is emerging (Wood et al., 2015). Like everywhere in the Arctic, understanding of environmental change in the Chukchi Sea is hindered by sparse data. Dynamics of the carbonate system (CS) in the eastern Chukchi Sea (US EEZ) has been studied more extensively for a longer period and is better understood than in its western (Russian EEZ) part. Here we focus on the carbonate system data collected in the Russian part of the Chukchi Sea over > 10 years (2000-2011).

Our data exhibit a strong mesoscale and interannual dynamics of carbonate system parameters in the surface seawater. The aragonite saturation state (W_Ar) was highly variable but also has generally been decreasing in the upper waters from 2000 to 2011. It was shown that despite strong sea ice loss, waters heating and storm increasing, the surface waters in this area have been consistently undersaturated by CO₂ with respect to the atmosphere. Notable localized exceptions, where CO₂ outgassing occurs, include the well-mixed waters near Bering Strait. Combining our long-term carbonate system data set (1996-2011) with the available literature data we felt in conclusion that the entire Chukchi Sea during ice-free season absorbs ~12-15× 10¹² g C and a significant part of this carbon was transferred to the deep layers and insulated from contact with the atmosphere for a long time. Note that the CO₂ invasion is a similar value with the CO₂ outgassing from the shallow eastern Laptev Sea and the western part of the East Siberian Sea.