Abstract
AbstractThe Barents Sea and its marine ecosystem is exposed to many different processes related to the seasonal light variability, formation and melting of sea-ice, wind-induced mixing, and exchange of heat and nutrients with neighbouring ocean regions. A global model for the RCP4.5 scenario was downscaled, evaluated, and combined with a biophysical model to study how future variability and trends in temperature, sea-ice concentration, light, and wind-induced mixing potentially affect the lower trophic levels in the Barents Sea marine ecosystem. During the integration period (2010–2070), only a modest change in climate variables and biological production was found, compared to the inter-annual and decadal variability. The most prominent change was projected for the mid-2040s with a sudden decrease in biological production, largely controlled by covarying changes in heat inflow, wind, and sea-ice extent. The northernmost parts exhibited increased access to light during the productive season due to decreased sea-ice extent, leading to increased primary and secondary production in periods of low sea-ice concentrations. In the southern parts, variable access to nutrients as a function of wind-induced mixing and mixed layer depth were found to be the most dominating factors controlling variability in primary and secondary production.
Highlights
The Barents Sea (BS) is the largest and deepest of the continental shelf seas surrounding the Arctic Ocean
An earth system model has here been downscaled for the RCP4.5 scenario for the period 2010–2070
The regional model was evaluated with respect to volume transports and sea-ice extent
Summary
The Barents Sea (BS) is the largest and deepest of the continental shelf seas surrounding the Arctic Ocean. Surface air temperatures in the Arctic have increased at twice the global rate (Hansen et al, 2006; Skagseth et al, 2015), where the spatially averaged warming north of 60N has been 1–2C since the temperature minimum in the 1960s and 1970s (IPCC, 2013). Both air and ocean temperatures show strong multi-decadal variability on timescales of 50–80 years (Zhang et al, 2007), and this large-amplitude multi-decadal climate variability impacting the Arctic may cause confusion in the detection of the true underlying climate trend over the past century (Polyakov et al, 2003). Variability in terms of atmospheric forcing and propagation of hydrodynamic anomalies in the ocean may work on different temporal and spatial scales
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