Evolution of Earth's geologic carbon cycle and long-term climate
The long-term carbon cycle - which operates over 100,000s to Millions of years - is regulated by fluxes of carbon between the solid Earth and the coupled ocean-atmosphere system. We work to understand how this system has evolved, and particularly how it has been linked to tectonic processes such as mountain uplift and continental breakup.
This work applies relatively simple models along with isotopic tools to unravel carbon cycle changes at key intervals of change in Earth's past. We are currently focusing particularly on intervals of significant change, including the Cenozoic (the last ~65 Million years) and the Triassic-Jurassic boundary, which marks a major mass extinction that was associated with large perturbations in the carbon cycle.
Research Focus Areas
Geomorphic and erosional controls on carbon cycle fluxes
Answering fundamental questions about the carbon cycle in the past - or about its future response to human modifications - relies on understanding the main fluxes of carbon in the Earth system. We are using the present- day Earth to study these fluxes. Our focus is on chemical weathering, which is important over geologic time, as well as the cycling of organic carbon, which is important both over geologic time and over shorter timescales, i.e. 100s of years. An extension of this work is to consider whether "enhanced weathering" could help to remove CO2 from the atmosphere. This work involves extensive field projects to exploit gradients in space and time that provide natural experiments for carbon cycle research, particularly for quantifying the role of erosion in the carbon cycle.
Erosion and mountain building over geologic time
The erosional processes that occur during mountain building link plate tectonics with Earth's surface environment, making erosion one of the major surface responses to the dynamic processes that are at work at depth in the Earth. We work to contribute to understanding the links between uplift, erosion, and topography. We are focusing on field-based studies of erosional processes in natural systems, applying a range of techniques including geochemical analyses (e.g., cosmogenic nuclide and thermochronology to quantify denudation rates) as well as remote sensing and topographic analysis. We have active projects in Mongolia, Sichuan, and the Banda Arc of eastern Indonesia - all facilitated through a wide collaborative network.
Geomorphic and erosional controls on life-sustaining soil, water and ecosystem processes in Earth's "Critical Zone"
The interacation of geomorphic, geochemical, and hydrologic processes produces soils, releases critical rock-derived nutrients, and regulates the quantity and quality of water resources. We are working on a range of questions about how the landscape-water-rock nexus influences nutrient supply and soil and water sustainability. Examples include work on hydrologic and erosional influences on nitrogen and nitrate in forested ecosystems, soil production rates and the sustainability of agricultural soils, and phosphorous and calcium supply from mineral weathering. We are also interested in role that "enhanced weathering" strategies may play in providing nutrients for agriculture, and in how rock-water interaction influences trace metal release and cycling.
The theme that unites my research is seeking to understand the how the dynamism of plate tectonics drives erosional processes that chemically refresh the Earth's surface and define the characteristics of the environment that supports life. You can see my publications listed by research focus area here...