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Blowin' in the wind: reconstructing ocean upwelling during high latitude cooling events!

by Dr. Louisa Bradtmiller, Macalester College

Presentation Overview

The strength and position of major wind belts - such as the trade winds and the westerlies - are determined in large part by the temperature gradient between the tropics and the poles in each hemisphere. These winds influence surface ocean circulation, and in regions of upwelling, changes in wind strength and position can increase or decrease the rate of upwelling and therefore the amount of biological productivity. On long timescales (10's to 100's of thousands of years), changes in Southern Ocean upwelling are associated with changes in deep ocean carbon storage, with periods of increased upwelling being associated with increases in atmospheric CO2. In this talk I will use biogenic opal - produced as the shells of diatoms and other organisms in upwelling regions, and measured in ocean sediment cores - to reconstruct upwelling in several regions of the ocean over the past ~million years. I will make connections between periods of high latitude cooling in both the North Atlantic and Southern Ocean regions and changes in upwelling, carbon storage and release, and past climate change. 

Biography

Dr. Louisa Bradtmiller is a paleoclimatologist/paleoceanographer interested in the ocean’s role in climate change on glacial-interglacial timescales. Her ongoing research uses ocean sediments to reconstruct past changes in ocean biogeochemistry and nutrient cycling, with a focus on the transfer of carbon between the ocean and atmosphere during periods of past climate change. Her recent research also includes investigations into changes in major monsoon systems on glacial-interglacial timescales as well as during abrupt climate transitions.

• BA in Geology, Smith College, 2002
• MA in Paleoceanography and Paleoclimate, Columbia University, 2005
• MPhil in Paleoceanography and Paleoclimate, Columbia University, 2006
• PhD in Geochemistry, Columbia University, 2008