University of California, Davis
February 22, 2022
20th century California Current System biogeochemistry
The productive California Current System is home to deep sea corals and is experiencing rapid surface ocean change. It is unknown to what extent the deep sea is impacted. Here, I will present a suite of organic skeletal parts from bamboo corals (Isidella sp.) that span a latitudinal gradient to probe the recent biogeochemical past of the California margin. We observe a shift in δ15N isotopic signatures and δ13C trends during the 20th century, and explore possible mechanisms. This work highlights the variability of the California Current System both spatially and temporally over decadal timescales, and the value of high-resolution ocean archives.
University of Hamburg
February 15, 2022
Marine redox fluctuations during the Ediacaran-Cambrian transition: Insights from chromium isotopes.
It has been suggested that the Cambrian diversification was brought on by a progressive rise in surface
oxygen levels. However, the idea of one major shift in marine redox across this interval is heavily
debated. Here, I will present chromium isotope data from Ediacaran-Cambrian marine sedimentary
successions from the Yangtze Block, South China. The chromium isotope data suggest that the Yangtze
Block underwent repeated shifts in redox state resulting in a highly dynamic environment, potentially
forcing biological adaptation.
University of Colorado, Boulder
February 8, 2022
Emerging Hydrologic Feedbacks on the Greenland Ice Sheet: What a rapidly changing climate is revealing about the ice sheet’s future and past
As Arctic climate warms, over the past few decades the Greenland ice sheet has undergone enormous hydrologic changes. Recent advances in satellite, airborne, and field-based observations are rewriting previous assumptions about how we believe the Greenland ice sheet behaves in a warming climate and also raising questions about its viability in the future. Simultaneously, recent evidence from ice core sediment records are revealing new details of the ice sheet’s past that have implications for the future of Greenland’s ice in a warming future. Join Dr. Mike MacFerrin as he reviews what glaciologists have recently been learning about how the Greenland ice sheet responds to a rapidly changing climate, the implications for interpreting its past, and the open questions being explored today about what the future holds for our northern ice sheet.
University of South Florida
February 1, 2022
Untangling the broad-scale evolutionary patterns of Paleozoic echinoderms
Echinodermata is an extremely diverse and long-lived phylum, whose fossil record provides a wealth of data upon which to test hypotheses of evolutionary patterns. In particular, the extinct stemmed blastozoan echinoderms have extremely disparate bodies that were likely responding to global extrinsic factors, such as major climate upheavals. This talk will focus on recent work on uncovering the phylogenetic, biogeographic, and disparity patterns observed in blastozoan echinoderms from the early Paleozoic and explore the possible global factors influencing these patterns.
University of the Witwatersrand, South Africa
January 25, 2022
Examining resilience and long-term rangeland health using multiple-proxy palaeoecological methods: an example from a South African grassland
Ecosystem health is an important measure of rangeland functioning and their capacity to provide essential ecosystem services. However, our understanding of ecosystem dynamics and health in landscapes used for centuries by pastoralists in African landscapes is poor. In this talk I discuss how the alternative stable states and resilience theories can be used a lens for examining long-term ecosystem health and degradation in an ancient South African landscape using multiple palaeoecological methods. The timeframe is the last 1 200 years. I also review implications for the conservation and restoration of similar ecosystems. Here is a link to our research paper https://iopscience.iop.org/article/10.1088/1748-9326/abdf87/pdf
Stanford University, USA
January 18, 2022
Terrestrial ecosystem resilience in the geologic past
How forests and grasslands respond to climate change remains debated, in part because of the complex interactions between these ecosystems and climate. Model results are highly sensitive to how these interactions are parameterized and the human observational record is too short to resolve large climate signals and long-term responses. Geologic archives, however, hold empirical evidence of the co-evolution of ecosystems and climate and they can be used to reconstruct ecosystem resilience. In this talk I will present two paleo case studies that inform the resilience of forests to drying—one from the late Quaternary Amazon Basin and the other from the Neogene western U.S. These examples emphasize the resilience of forests to climate change and indicate that excessive anthropogenic deforestation and fire likely pose a more urgent threat to forests than climate change alone.
December 7, 2021
Navigating Grad School
Dr. Jorge Cardich (Universidad Peruana Cayetano Heredia, Peru),
Dr. Gabi Serrato-Marks (Broad Institute of MIT and Harvard, USA),
Dr. Flavia Boscolo-Galazzo (University of Bergen, Norway),
Dr. Advait Jukar (Yale University, USA),
Dr. Pedro Monarrez (Stanford University, USA),
Dr. Tripti Bhattacharya (Syracuse University, USA),
Dr. Omar Rafael Regalado Fernández (Universität Tübingen, Germany)