How important is carbon storage by southern polar benthos as a negative feedback on climate change?

Christoph.Held [ at ]


Carbon capture and storage by southern polar benthos is potentially the largest negative feedback on climate change. Most feedbacks on global climate change are positive; they exacerbate physical change. The few known strong negative feedbacks, those which reduce physical change, are polar, and include i) broadening existing sinks with sea-ice losses over polar continental shelves, ii) subarctic vegetation growth increases and iii) formation of new sinks where ice shelves collapse. To date, carbon sequestration gains have been recorded around the Antarctic coastal shallows where they are likely to be offset by fjordic losses associated with sedimentation, and open coast losses through increased iceberg scouring. These feedbacks are complicated by additional positive forcing associated with greater heat absorption from albedo change. In contrast there is no albedo change (negligible sea ice losses) over sub-Antarctic shelves, where rising sea temperatures are likely to increase carbon storage by animals. The continental shelves along polar continent margins and archipelagos are wide, deep and rich in life. Most species known from polar waters live on these shallower shelf regions and it has been observed that they play an increasingly important role in the carbon cycle. Carbon is transported through the system by being fixed in photosynthesis by algae, which are eaten by benthic invertebrates, and then buried when the animal dies. We aim to measure how much carbon is held per unit area of the seabed per year and how this varies in time and space. Teasing apart biological processes in these important geographic regions is vital to our understanding of global carbon capture. One of the biggest sources of error in this regard is understanding the extent to which these feedbacks are effects of climate forcing on sub-Antarctic and Arctic shelf benthos performance. This type of carbon sequestration, termed blue carbon (associated with natural processes), is likely to increase, so long as sea ice and ice shelf losses continue to be sustained. Our research project, titled Antarctic Seabed Carbon Capture Change (ASCCC) has participated in the Antarctic Circumnavigation Expedition (ACE) in 2016 and 2017 to address the question ‘How will regional warming influence how much carbon is captured and stored by life on the seabed around Antarctica and the sub-Antarctic?’, from which we plan to estimate increased benthic carbon stored across the southern polar region due to recent ice shelf losses, sea ice losses and temperature increases.

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Conference (Talk)
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SCAR conference Leuven, 01 Jul 2017 - 01 Jul 2017, Leuven, Belgium.
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Bax, N. , Moreno, B. , Moreau, C. , Barnes, D. K. A. , Paulsen, M. , Held, C. , Downey, R. and Sands, C. J. (2017): How important is carbon storage by southern polar benthos as a negative feedback on climate change? , SCAR conference Leuven, Leuven, Belgium, July 2017 - July 2017 .

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