Paul de Konkoly Thege ’14 on “Ocean-Climate Dynamics: Using Carbon-14 to Reconstruct Past Ocean Circulation in the Bering Sea”

Environmental Science major, Paul de Konkoly Thege ’14 presented his senior thesis research at log lunch on April 25, 2014. His research was focused on studying ocean circulation to learn more about rapid climate change.

De Konkoly Thege first explained the two basic types of ocean circulation: surface ocean circulation and deep ocean circulation. Surface ocean circulation is due to the heating differential between the equator and the poles that creates winds that drives ocean circulation. Deep ocean circulation is due to thermohaline circulation which involves the density differences of deep water due to heat and salt. The Atlantic meridional overturing circulation (AMOC) is an example of thermohaline circulation and is well studied. However, his research was learning about the Pacific deep ocean circulation.

De Konkoly Thege studied a sediment core from the Beiring Sea to examine changes in ocean circulation since the last deglaciation twenty thousand years ago. Initially, he hypothesized an antiphase relationship between the north and south pacific circulation. He used radiocarbon to determine the circulation of the surface ocean. Much of his work was through foraminifera precipitation of calcium carbonate shells in the cores that contain a signature of the radiocarbon of the water during the time in which it suck into the sediment. De Konkoly Thege converted the calcium carbonate into pure carbon and measured ratios of isotopes of carbon to calculate an age based on isotopes. He also used volcanic ash layers as age control points. Once he gathered all the data, he looked at several geological intervals and discovered that the data did not perfectly align with his antiphase hypothesis. However, he concluded that ocean circulation is highly complex and simplifying it would not always work out especially due to regional variation. He said that independent age models, like the one created, could be used to study more local data than global data.

By Helen Song ’14

Paul de Konkoly Thege '14

Paul de Konkoly Thege ’14