High interannual surface pCO.sub.2 variability in the southern Canadian Arctic Archipelago's Kitikmeot Sea

Warming of the Arctic due to climate change means the Arctic Ocean is now free from ice for longer, as sea ice melts earlier and refreezes later. Yet, it remains unclear how this extended ice-free period will impact carbon dioxide (CO.sub.2) fluxes due to scarcity of surface ocean CO.sub.2 measureme...

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Bibliographic Details
Published in:Ocean science 2023-06, Vol.19 (3), p.837
Main Authors: Sims, Richard P, Ahmed, Mohamed M. M, Butterworth, Brian J, Duke, Patrick J, Gonski, Stephen F, Jones, Samantha F, Brown, Kristina A, Mundy, Christopher J, Williams, William J, Else, Brent G. T
Format: Article
Language:English
Subjects:
Global temperature changes
Sea ice
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Summary:Warming of the Arctic due to climate change means the Arctic Ocean is now free from ice for longer, as sea ice melts earlier and refreezes later. Yet, it remains unclear how this extended ice-free period will impact carbon dioxide (CO.sub.2) fluxes due to scarcity of surface ocean CO.sub.2 measurements. Baseline measurements are urgently needed to understand spatial and temporal air-sea CO.sub.2 flux variability in the changing Arctic Ocean. There is also uncertainty as to whether the previous basin-wide surveys are representative of the many smaller bays and inlets that make up the Canadian Arctic Archipelago (CAA). By using a research vessel that is based in the remote Inuit community of Ikaluqtuutiak (Cambridge Bay, Nunavut), we have been able to reliably survey pCO.sub.2 shortly after ice melt and access previously unsampled bays and inlets in the nearby region. Here we present 4 years of consecutive summertime pCO.sub.2 measurements collected in the Kitikmeot Sea in the southern CAA. Overall, we found that this region is a sink for atmospheric CO.sub.2 in August (average of all calculated fluxes over the four cruises was -4.64 mmol m.sup.-2 d.sup.-1 ), but the magnitude of this sink varies substantially between years and locations (average calculated fluxes of +3.58, -2.96, -16.79 and -0.57 mmol m.sup.-2 d.sup.-1 during the 2016, 2017, 2018 and 2019 cruises, respectively). Surface ocean pCO.sub.2 varied by up to 156 µatm between years, highlighting the importance of repeat observations in this region, as this high interannual variability would not have been captured by sparse and infrequent measurements. We find that the surface ocean pCO.sub.2 value at the time of ice melt is extremely important in constraining the magnitude of the air-sea CO.sub.2 flux throughout the ice-free season. However, further constraining the air-sea CO.sub.2 flux in the Kitikmeot Sea will require a better understanding of how pCO.sub.2 changes outside of the summer season. Surface ocean pCO.sub.2 measurements made in small bays and inlets of the Kitikmeot Sea were ⼠20-40 µatm lower than in the main channels. Surface ocean pCO.sub.2 measurements made close in time to ice breakup (i.e. within 2 weeks) were ⼠50 µatm lower than measurements made 4 weeks after breakup. As previous basin-wide surveys of the CAA have focused on the deep shipping channels and rarely measure close to the ice breakup date, we hypothesize that there may be an observational bias in previous stud
ISSN:1812-0784
1812-0792