GEOL Dissertation Defense - Natalie UmlingFriday, July 7, 2017 - 12:00pm
Glacial to Holocene Changes in Eastern Equatorial Pacific Deep-Water Chemistry and Circulation
It has been hypothesized that the oceans store CO2 during glacial periods and then release it to the atmosphere, causing the onset of warm interglacial periods (Sigman and Boyle, 2000). Documenting this past transfer of CO2 between the oceans and atmosphere is of utmost importance for better understanding the impact that anthropogenic CO2 has and will have on Earth’s climate. The last deglaciation is a good analogue to modern increases in CO2 and temperature and is recent enough to be studied using radiocarbon. This period provides important insights into the nature of climate changes during the transition from glacial to interglacial conditions. Specifically, this transition is punctuated by brief periods of rapid return to cold, glacial-like conditions followed by abrupt warmings that are synchronous with increases in atmospheric CO2 depleted in 14C (Hughen et al., 2000; Monnin et al., 2001). This link between increasing atmospheric CO2 and abrupt temperature rise during deglaciation has prompted the search for the location of a suitably large 14C-depleted pool of respired carbon in the oceans that could serve as the source for these large increases in atmospheric CO2. Changes in the efficiency of the biological pump and in meridional overturning circulation have both been cited as possible mechanisms of respired carbon storage. We seek to understand the role of these mechanisms in the Eastern Equatorial Pacific (EEP) over the last 25,000 years using a combination of radiocarbon, trace element, and isotopic studies of deep-ocean chemistry.