E.: Vulnerability of polar oceans to anthropogenic acidification: comparison of Arctic and Antarctic seasonal cycles., Sci

• Main Authors: E H Shadwick, T W Trull, H Thomas, J A E Gibson
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2013
• Subjects: Antarctic; Arctic; Prydz Bay; The Antarctic; Amundsen Gulf; Antarc*; Climate change; Sea ice
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1068.7780; http://www.phys.ocean.dal.ca/%7Ehelmuth/papers/shadwick_et_al_2013.pdf

Polar oceans are chemically sensitive to anthropogenic acidification due to their relatively low alkalinity and correspondingly weak carbonate buffering capacity. Here, we compare unique CO 2 system observations covering complete annual cycles at an Arctic (Amundsen Gulf) and Antarctic site (Prydz Bay). The Arctic site experiences greater seasonal warming (10 vs 36C), and freshening (3 vs 2), has lower alkalinity (2220 vs 2320 mmol/kg), and lower summer pH (8.15 vs 8.5), than the Antarctic site. Despite a larger uptake of inorganic carbon by summer photosynthesis, the Arctic carbon system exhibits smaller seasonal changes than the more alkaline Antarctic system. In addition, the excess surface nutrients in the Antarctic may allow mitigation of acidification, via CO 2 removal by enhanced summer production driven by iron inputs from glacial and sea-ice melting. These differences suggest that the Arctic system is more vulnerable to anthropogenic change due to lower alkalinity, enhanced warming, and nutrient limitation. T he polar oceans are sensitive to increasing global temperature and increasing concentrations of atmospheric carbon dioxide (CO 2 ) (refs. 1, 2), with the impacts of climate change expected to be particularly large in icecovered regions. Compared to other oceans, the Arctic and Southern Oceans remain under-studied at the annual scale, with the majority of observations restricted to the ice-free summer and autumn seasons