Understanding Deep-Ocean Circulation during Miocene Climate Transition: Are Freshwater Impacts the Key?

This award provides funds to conduct a multiple stage modeling study to investigate the role of freshwater inputs to the oceans and its influence on climate.

Initially, the investigators will carry out fully coupled climate modeling experiments to generate a climate 'reference state' for the Early and Late Miocene. Next, they will complete a series of ocean model experiments for each of the two periods to target the role of high-latitude in affecting ocean surface conditions. This effort will focus on the role of freshwater dynamics in altering the deep-ocean thermohaline circulation for differing ocean-land configurations. The results from these experiments will be compared to paleoceanographic data to determine which ocean solution best corresponds to the paleoceanographic record for these time intervals. In the last stage of modeling, the research team will use best-fit results from the ocean model experiments as a foundation for additional coupled model experiments.

The Miocene was a notable step in the transition from global conditions of warm equable climates to a climate with persistently cold polar regions. This was accompanied by a fully developed southern cryosphere and the initiation of northern hemisphere ice. It is hypothesized that the initiation of Antarctic continental glaciation resulted from tectonic activity during the Miocene. This resulted in a major reorganization of deep ocean circulation that played a key role in the evolution of cooling polar climates.

The main research objective of this award is to attempt to mimic the Miocene climate transition based on the connections between the freshwater impacts associated with a developing southern ocean-based cryosphere and intensification of the Antarctic Circumpolar Current (ACC). As such, the investigators hope to contribute to an improved understanding of the dynamics of the Miocene climate transition, especially with regards to the role of freshwater input in impacting climate.

This research will provide a broader understanding of Earth' climate during an important transition in its history when the physical features began to appear as they are in the modern world (i.e., continental separation, establishment of polar ice caps, circum-Antarctic ocean circulation).