We currently have several funded projects to look at 1) End-Cretaceous mass extinction; 2) Miocene co-evolution of landscape, climate, and biodiversity; 3) Mid-Pliocene storms and the North American monsoon; 4) Last Glacial Maximum hydroclimate in Southwest US. Please contact us for additional information, possible collaborations, and research opportunities!
End-Cretaceous mass extinction
Over 75% of all species went extinct across the Cretaceous-Paleogene Boundary (66 million years ago). This extinction coincided with a massive asteroid impact in the Yucatan Peninsula, which emitted gases and particles high into the atmosphere and caused widespread fires. We are using an Earth system model to simulate the climate responses to emissions of dust and sulfur from the impact and soot from fires. (Collaborating with Prof. Lovenduski and Prof. Sepulveda at University of Colorado, Dr. Bardeen at NCAR, Prof. MacLeod at University of Missouri, Prof. Mitra at Eastern Carolina University, Prof. Harrison at University of Texas-RGV)
Miocene co-evolution of landscape, climate, and biodiversity
In the middle Miocene, a pulse of mammal diversity tracks the rate of extension within the collapsing orogen of what is now the Basin and Range province. Using constraints from the models of paleotopography and climate, we test hypotheses that relate these dramatic changes in mammal diversity to the development of large-scale gradients in topography, climate, and the removal of large topographic barriers (Collaborating with Prof. Holt and Prof. Smiley at Stony Brook University, Prof. Badgley at University of Michigan). We are also researching South American monsoon evolution during the middle Miocene climate optimum. (Collaborating with Prof. Carrapa at University of Arizona, Prof. Clementz at University of Wyoming)
Mid-Pliocene storms and the North American monsoon
Recent multi-year droughts in the American Southwest highlight the need to improve predictions of southwest climate responses to rising greenhouse gases. Climate model experiments of future emissions scenarios as well as past warm intervals like the mid-Pliocene (3.0 – 3.3 Ma) predict widespread drying in response to rising greenhouse gases. However, proxy records suggest wet conditions during the Pliocene, in direct contradiction with simulations. We are carrying out a suite of high-resolution Earth system model simulations to explore mid-Pliocene changes in the North American Monsoon (NAM) as well as other fine-scale circulation features that may bring precipitation to the western North America in a warm world. (Collaborating with Prof. Bhattacharya at Syracuse University)
Last Glacial Maximum Hydroclimate in Southwest US
Southwest North America is one of the world’s most climatically sensitive regions with inherently variable hydroclimate. Evidence exists for repeated, large regime shifts in this region’s hydroclimate at the sub-decadal to millennial-scale during the last glacial cycle and Holocene, but the mechanisms driving this change remain uncertain. We are conducting high-resolution Earth system simulations to evaluate how North Pacific storm track behavior and the resulting precipitation signal is archived in the stalagmite proxy records, and the mechanisms underlying changes in precipitation in the context of the changing environmental forcings of the past 21,000 years (Collaborating with Prof. Montañez at UC Davis, Prof. Oster at Vanderbilt University, Prof. Lofverstrom at University of Arizona).