Changes in the marine carbonate system of the western Arctic: patterns in a rescued data set

Abstract

A recently recovered and compiled set of inorganic carbon data collected in the Canadian Arctic since the 1970s has revealed substantial change, as well as variability, in the carbonate system of the Beaufort Sea and Canada Basin. Whereas the role of this area as a net atmospheric carbon sink has been confirmed, high pCO 2 values in the upper halocline underscore the potential for CO 2 outgassing as sea ice retreats and upwelling increases. In addition, increasing total inorganic carbon and decreasing alkalinity are increasing pCO 2 and decreasing CaCO 3 saturation states, such that undersaturation with respect to aragonite now occurs regularly in both deep waters and the upper halocline.

Modeled Impacts of Sea Ice Exchange Processes on Arctic Ocean Carbon Uptake and Acidification (1980–2015)

“…The simulated progression of annually averaged DIC in the upper 300 m of the water column for both the Beaufort Sea basin and shelf over the period of the standard run (Mortenson, 2019) is similar to that observed by Miller et al (2014). Although the simulated surface Ω arag is lower than observed, the decrease in subsurface Ω arag over time (Figures 6a and 6b) is consistent with observations of both Qi et al (2017) and Bellerby et al (2018).…”

“…The Arctic has also undergone biogeochemical changes. In particular, it has become lower in pH and the calcium carbonate saturation state of the biologically relevant forms aragonite and calcite, Ω arag and Ω calc , have decreased faster than the global ocean-averaged trends (Bellerby et al, 2018;Miller et al, 2014;Steiner et al, 2015;Wallhead et al, 2017).…”

Freshwater and its role in the Arctic Marine System: Sources, disposition, storage, export, and physical and biogeochemical consequences in the Arctic and global oceans

“…Changes in environmental parameters over the past two decades (increased river discharge, warming, melting of sea ice, and increased primary productivity) are affecting the rate of acidification in the Arctic Ocean. Time series observations have revealed significant decrease in pH and calcium carbonate saturation state (Ω) in Iceland and Nordic Seas from 1985 to 2008 [ Olafsson et al ., ] and in Canada Basin from 1997 to 2008 [ Yamamoto‐Kawai et al ., ; Miller et al ., ]. In the former region, ocean acidification was enhanced by a surface ocean p CO 2 increase slightly exceeding the atmospheric CO 2 growth rate, due probably to decadal timescale climate variability [ Thomas et al ., ; McKinley et al ., ].…”

Impacts of the Changing Ocean-Sea Ice System on the Key Forage Fish Arctic Cod (Boreogadus Saida) and Subsistence Fisheries in the Western Canadian Arctic—Evaluating Linked Climate, Ecosystem and Economic (CEE) Models

“…Past environmental changes in the Western Canadian Arctic have been highlighted in recent assessments (e.g., Steiner et al, 2015a;AMAP, 2017) and show atmospheric and oceanic temperature increases, intense summer sea-ice retreat and thinning, particularly in the Beaufort Sea, as well as changes in stratification. In the Western Canadian Arctic the progression of ocean acidification is indicated by a significant northward expansion of waters with low aragonite saturation state, and upper halocline waters and deep waters now regularly showing aragonite undersaturation particularly in the off-shelf waters (Miller et al, 2014;Qi et al, 2016;AMAP, 2018). Global Earth System Model (ESM) projections suggest the marine environment in the western Arctic is likely to experience large changes with suggested atmospheric temperature increases of 0-3 • C in summer and 3-7 • C in winter over the next 50 years (Steiner et al, 2015a).…”