National Science Foundation/USGS Internship Opportunities

Holocene seasonal climatology in south-central Alaska from intra-annual oxygen and carbon isotopes of fossil wood


This project will utilize isotopic analyses of a unique archive of fossil wood spanning ~10,000 years in the Wrangell-St. Elias region of south central Alaska to document variations in Holocene seasonality of temperature and precipitation.

Link to PDF Verison.

Project Hypothesis or Objectives:

In the coastal mountain ranges of southern Alaska, which support large ice fields and glaciers, intensification and southward migration of the polar jet stream currently leads to the winter organization of the Aleutian Low and greater winter precipitation amounts. Holocene paleoclimate data indicates changes in atmospheric circulation related to external solar insolation as well as internal sub-tropical and arctic dynamics.  Modern and fossil wood provides the opportunity to investigate how circulation changes have previously affected seasonal climatology from isotope measurements of incremental slices taken from within annual tree rings. Preliminary intra-annual isotope measurements of remnant spruce (Picea) fragments spanning early to late Holocene ages from the Copper River in the Wrangell-St. Elias region of south-central Alaska indicate differences but to fully realize the potential of this geologic archive more sample collections and analyses are needed.  Recently developed empirical models from global meta-analyses of tree cellulose isotope are available but the interpretive strength is highly dependent on sample size. There is a tradeoff between the sample size need and the opportunity to expand the temporal continuity of the archive; innovative research approaches are needed to optimize both goals.

Duration: Up to 12 months

Internship Location: Denver, CO

Field(s) of Study: Geoscience, Holocene paleoclimatology, cellulose isotope geochemistry, dendrochronology

Applicable NSF Division: AGS Atmospheric and Geospace Sciences, EAR  Earth Sciences, PLR Polar Programs

Intern Type Preference: Either Type of Intern

Keywords: Climate change, isotopes, Alaska, tree rings

Expected Outcome:

The intern will gain professional experience at a federal research facility as a member of a collaborative research team. We expect that the intern will develop skills needed to succeed as a research scientist, including hypothesis development, field and laboratory work, and data interpretation through writing.  The USGS will benefit from the intern by their contribution to our research goals and by supporting and mentoring students on research career paths.

Special skills/training Required:

Experience in light stable isotope geochemistry (C and O) and paleoclimate are central to this position.  The applicant should be familiar with dendrochronological tools and field experience is desired. Applicants should be comfortable working with statistical modeling platforms, such as R.  Creative ability with MATLAB is highly desirable. Applicants should have degrees in Geology and experience with Holocene paleoclimate from geologic archives, preferably in Alaska and/or other high latitude environments.


The internship will be responsible for 1) additional field sampling of modern and fossil wood, dendrochronology, intra-ring sampling and cellulose isotope analyses, 2) comparison between modern wood isotope results and climatology towards expanded development of empirical models, and 3) application of empirical models to fossil wood results.  Additional avenues of exploration to aid the interpretation of cellulose isotope results may also include process-based approaches such as in situ isotope measurements and process model development and application. The intern will be expected to present the research results at a national or international conference.


Lesleigh Anderson

Research Geologist
Geosciences and Environmental Change Science Center
Phone: 303-236-1296