Speaker: Chris Lowery, Research Associate, UTIG
Host: Gail Christeson
Title: The Chicxulub Impact and the Resilience of Life
Abstract: Look, we all know there have been a lot of Chicxulub talks around here over the past few years. I'm going to focus on putting the new results from that drilling expedition back into the big picture of the Cretaceous-Paleogene (K-Pg) mass extinction and the evolution of life more generally. The worst environmental effects of the impact were over within a few years, and the extinction of 76% of species in the fossil record occurred within that short window of time. It is surprising, then, that the recovery of the marine biological pump took 1.8 million years, and the recovery of biodiversity in a number of marine groups took over 10 million years. This gets at a fundamental question of macroevolutionary research: is evolution primarily driven by external, abiotic factors or internal, ecological and biological factors? This is not an abstract theoretical problem but an extremely relevant and pressing one, given alarming modern declines in global biodiversity. How long will it take for biodiversity to recover once negative anthropogenic pressures are removed? I will summarize how the recent work on marine microfossils by myself and colleagues has contributed to our overall understanding to the short term and long term recoveries of life following the Chicxulub impact, and what major unknowns still need to be investigated.
Speaker: Yi Fang, Postdoctoral Fellow, UTIG
Host: Peter Flemings
Title: Permeability of a methane hydrate reservoir in the Gulf of Mexico
Abstract: Methane hydrates, ice-like solids composed of methane and water, are stable in continental margin sediments. They are a large potential energy resource and play an important component of the carbon cycle and may impact climate change. To understand their role in these processes, we must understand how they form and how they might be produced. Many quantitative models have been developed to describe these processes. All of them critically depend on understanding of the flow properties of hydrate-bearing material, which are virtually unknown. I have spent two years studying these properties in the laboratory. We recovered pressurized cores from a sandy silt with ~90% hydrate saturation in deepwater Gulf of Mexico (GOM). We measured effective permeability in these samples and found permeabilities around ½ millidarcy (mD) at in-situ stress. We also reconstituted sandy silt sediments to predict its in-situ intrinsic permeability (11.8 mD) and to explore its relationship to porosity. Ultimately, our study will inform numerical models with permeability properties at scales of individual lithofacies.
Speaker: Donald Slater, Postdoctoral Scholar, Scripps Institution of Oceanography
Host: Ginny Catania
Title: Effect of ocean variability on the Greenland Ice Sheet in the 20th and 21st centuries
Abstract: In recent decades, more than 95% of marine-terminating glaciers around the Greenland ice sheet have retreated, driving dynamic thinning of the ice sheet periphery and contributing significantly to sea level. These changes have been attributed largely to a warming of the ocean surrounding Greenland, and the subsequent increase in submarine melting of tidewater glacier calving fronts. Understanding the interaction of glaciers with the ocean is therefore thought to be a key process modulating Greenland ice sheet stability, yet is currently poorly understood.
This seminar will cover three related studies on Greenland ice sheet-ocean interactions. The first pairs unique ocean observations from within meters of a tidewater glacier with high-resolution ocean modeling to show that drainage of freshwater from beneath the glacier drives a fjord-wide circulation that doubles the total submarine melt rate. The second study addresses submarine melt variability at all of Greenland’s tidewater glaciers over the past century, suggesting that the atmosphere drives as much variability in submarine melting as the ocean. Lastly I will describe how ocean forcing of the Greenland ice sheet is represented in ISMIP6, our leading community effort to produce ice sheet sea level projections for the next IPCC assessment report. Together these studies go from detailed process understanding to Greenland ice sheet-wide sea level projections, along the way highlighting key unknowns and sources of uncertainty.
Cancer surgeries are complex procedures that require high levels of precision. New technologies that allow rapid and accurate detection of cancer during surgery could significantly improve treatment of cancer patients. Dr. Eberlin will share her team's breakthrough in developing the MasSpec Pen technology for rapid and accurate cancer detection during surgery.