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Interdisciplinary Seminar: Chuxuan Li

March 4, 2019 @ 12:20 pm - 1:20 pm

photo of UNC Marine Sciences graduate student Chuxuan LiAn interdisciplinary seminar from UNC Marine Sciences graduate student, Chuxuan Li.

Presented by the UNC at Chapel Hill Department of Marine Sciences. The location of this event will be in seminar room G201 on the ground floor of Murray Hall on UNC-CH campus in Chapel Hill, NC. This event will be held on Monday, March 4th at 12:20pm. This seminar will also be broadcast live to both UNC’s Institute of Marine Sciences room 222 and online via Zoom (Meeting ID: 117-856-429).

Seminar Title: How do climate-driven changes affect phytoplankton in the Southern Ocean? -the role of CO2

Abstract: The Southern Ocean (SO), an oceanic division that has the strongest uptake for anthropogenic carbon dioxide (ACO2), accounts for up to 40% of the total amount of the ACO2 sequestered by the world’s oceans. As ACO2 emissions continue to increase through burning fossil fuels, the physical and chemical environments in the SO have altered. Under climate change, the Southern Hemisphere experienced a shift towards a more positive phase of the Southern Annular Mode (SAM) since 1990s. Enhanced upwelling associated with positive SAM caused a weakened CO2 uptake in the SO from 1990s-early 2000s, which was then followed by a reinvigorated carbon sink related to a trend towards a zonally more asymmetric atmospheric circulation. Surface seawater is absorbing more ACO2 and the pH in the SO has been decreasing since industrial revolution. These climate-driven changes in the physical and chemical conditions are likely enhancing the primary productivity of phytoplankton south of the Polar Front, increasing diatom abundance and killing calcifying organisms. Under a ‘business-as-usual’ ACO2 emissions scenario, warming-induced stratification, which inhibits vertical mixing, will compete against the enhanced upwelling associated with the strengthened positive SAM to determine the sign and magnitude of future changes in the SO net primary productivity. It is still demanding to accurately predict what the future holds, and the feedback on climate by marine organisms and the interplay between different factors in the SO make predictions even more complicated.

photo of an iceberg

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Date:
March 4, 2019
Time:
12:20 pm - 1:20 pm
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