Research

Permafrost stores a globally significant amount of carbon. With anthropogenic warming, this carbon is susceptible to greenhouse gas release. I use sediment cores drilled from permafrost to understand how past climate, hillslope processes and microbial degradation influenced permafrost carbon stored in Arctic hillslopes. I use a variety of biogeochemical indicators to look at organic matter degradation, such as amino acids, C:N ratios and pollen preservation.

Check out our 2023 paper in JGR Biogeosciences investigating organic matter in Holocene permafrost deposits along a central Alaskan hillslope, and our NSF project website where you can find data associated with this project.

Lake sediments are excellent archives of past climate and environmental change. I use Arctic lake sediment cores that record changes over the deglacial period to Holocene (last ~15,000 years) to better understand past carbon accumulation and landscape productivity. To do this, I analyze a variety of geochemical and physical indicators, including biogenic silica, carbon abundance and particle size.

Check out our 2025 paper in Arctic, Antarctic and Alpine Research where we research millennial-scale changes in carbon accumulation across the Eight Mile Lake watershed using lake and soil sediment cores. Our NSF project website hosts data associated with this project.

Radiocarbon is a geochronological tool used in many paleoclimate studies. It can also provide important insight into carbon cycling, when dating different pools of carbon. My work leverages the age offsets between macrofossils (representing "true" depositional age) and bulk sediments (integrating ages of many carbon pools) in lake sediment cores to understand how and when carbon is mobilized in Arctic watersheds.

For a great paper on this topic, see Ben Gaglioti et al.'s paper on age offsets and permafrost carbon from northern Alaska. And for more information about the NAU Radiocarbon lab, check out the Arizona Climate and Ecosystems Isotope Lab.