Funding is provided to investigate physical mechanisms responsible for the 41,000 year glacial cycles of the Late Pliocene and Early Pleistocene. The premise of the research is that the glacial cycles of this time are an enigma with respect to existing theories of climate.
The de facto application of the standard Milankovitch model predicts that Northern Hemisphere (NH) ice volume should vary linearly and coherently with NH summer insolation (i.e., June 65°N) at the obliquity (41,000 year) and precession (21,000 year) cycles. Yet, the data indicates that the precession frequency is only barely discernable in a small section of Late Pliocene ice volume records.
Similarly, most computer models that have been used to study the climate history of the Late Pliocene and Early Pleistocene interval also predict a strong precession signal in the modeled ice volume. The researcher poses the questions; "Are numerical climate models missing some fundamental piece of climate or ice sheet physics? Or is it our assumptions about ice volume proxies that are flawed?"
Specifically, the researcher will evaluate the signal of meltwater outflow from the Mississippi Drainage Basin in the Gulf of Mexico to test two competing hypotheses to explain the conundrum of the 41,000 year Milankovitch cycle world. The first hypothesis is the integrated insolation hypothesis of Huybers that predicts the timing of ablation/meltwater events on the southern margin of the Laurentide ice sheet should be paced by obliquity. The other is the anti-phase precession ice hypothesis of Raymo which predicts that Laurentide ablation/meltwater events should be paced strongly by precession.
The broader impacts involve a strong educational mentoring portion and an equally strong intellectual portion that may help lead to transformative advances in understanding ice sheet and sea level dynamics.
