Research Projects

The past always repeats itself, and global climate change is no exception. In fact, we might even say that the past prefers to repeat itself! Over the past 600,000 years, the climate has loyally trudged through one ice after another, six times in a row. How are these ice ages similar, and why? How are they different, and why? What drives their clockwork? These are just some of the questions driving my current research into the mechanisms and conditions of glacial-interglacial climate change in the Late Pleistocene. I work in many different locations, from the tropical Atlantic to the tropical Pacific and into the Bering Sea.

Tropical Pacific

Extending about 11,000 miles, the Tropical Pacific amounts to the greatest expanse of tropical ocean on Earth. Today, upwelling along the equator and the eastern boundary of South America brings more nutrients to the surface than the phytoplankton community can consume. How has the productivity of this massive region responded to changing climate conditions in the past? How has carbon storage in the deep Pacific varied with CO2 concentrations in the atmosphere? I focus on reconstructing productivity, inorganic and organic carbon fluxes, and circulation over the last 30 kyr to identify the major drivers of the biological pump and carbon storage in this region.

Tropical Atlantic

Oxygen is a primary component of the biological and chemical cycles of the ocean. Its involvement in photosynthesis and respiration links the variability of oxygen to that of carbon in the ocean, and ultimately in the atmosphere. As the oceans take up anthropogenic carbon, oxygen concentrations in the ocean are declining, with the potential to reach levels low enough to reduce biodiversity and possibly even limit life. During the last ice age, the oceans sequestered the equivalent of 100ppm of CO2, and this time period provides a natural experiment to investigate how oxygen concentrations may have vary under different climate conditions.

Northeast Pacific

Bathed in the oldest, most corrosive deep waters, the Northeast Pacific is not the easiest place for paleoceanography. As the high corrosivity dissolves the carbonaceous foraminifera, so to dissolves the possibility of constructing age models. The Northeast Pacific has been stuck in a dead zone, but in 2014, new cores were collected from the Juan de Fuca Ridge, bathymetrically high enough to escape complete carbonate dissolution. These foram-rich cores provide the opportunity to investigate a host of classic paleoceanographic questions in this region over the past 500,000 yrs, including mass fluxes, surface productivity, and ocean circulation.