An assessment of MOSJ: the state of the marine climate system around Svalbard and Jan Mayen

Svalbard’s climate is strongly influenced by the adjacent seas. Late-summer measurements collected over the last 52 years show that the temperature of warm Atlantic water flowing into the Arctic Ocean via in the West Spitsbergen Current has increased by 1.4 – 1.7 °C during the measurement period, equivalent to a rate of 0.27 – 0.33 °C per decade. The rate of warming has remained rather constant over the 52-year measurement period, excepting two warm (2005-2006, 2016-2017) anomalies and onecool (1998) anomaly. The West Spitsbergen current is an extension of the North Atlantic drift system and the trends observed in Eastern Fram Strait are largely due to increases in the temperature of water transported northwards from the sub-polar and sub-tropical Atlantic. Similar warming trends have been observed at other observatories along the North Atlantic Current system. The causes of this warming trend are the subject of ongoing research, and relevant factors include: variations in subtropical Atlantic water temperature; the rate of advection along the North Atlantic Current and the extent of wind induced surface cooling on route.

The marine environment of many Svalbard fjords is strongly influenced by warm Atlantic water supplied by the West Spitsbergen Current or Barents Sea (at depth) and by glacial meltwater supplied from Svalbard glaciers (at the surface). Increased freshwater addition decreases aragonite and calcite saturation (Ω) and pH level, and increases the ocean acidification state to levels that are critical for calcium-carbonate forming marine organisms. Particularly sensitive to this change is the aragonite-shell forming pteropod Limacina helicina, living in fjords and areas that are already near critical limits (Ω< 1.4) for calcification.

The Svalbard fjords Kongsfjorden and Tempelfjorden are experiencing increased ocean acidification state (OA) due to several factors: increased COdue to anthropogenic CO2 uptake in the Atlantic water outside the fjords, increased Co2 due to more inflow of Co2- rich Coastal Current water, and increased OA due to increased addition of glacial water. However, there are seasonal and inter-annual variability as well as biological Co2 consumption that balance parts of the increased Co2.

In Storfjorden, OA increases due to sinking of CO2-equilibrated surface water during sea-ice and brine formation. CO2-rich brine contributes to the relatively high CO2 concentrations (low pH) at the bottom of the fjord.

 

 

Renner A. H. H., Dodd P. A. & Fransson A., 2018. An assessment of MOSJ: the state of the marine climate system around Svalbard and Jan Mayen. Norsk Polarinstitutt, 48 p. Report.

 

 

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