My research interests are broad, but all revolve around the use of environmental stable isotope ratios.
I established and operated the Stable Isotope Laboratory for the analysis of stable isotope ratios of carbon, hydrogen, nitrogen, oxygen and sulfur. My specific areas of research include modeling the global carbon cycle using isotope ratios in atmospheric carbon dioxide and methane, development of techniques for measuring isotope ratios in atmospheric gases, reconstructions of paleo-environmental conditions using isotopes in ice cores, reconstructions of past environments from isotopes in organic materials, and tracing of ground water flow and recharge. I have been a member of several deep ice coring projects in Greenland (GISP2, NorthGRIP, and NEEM) and Antarctica (Siple Dome and Inland WAIS). I am also an affiliate of NOAA and work closely with the Carbon Cycle Group there.
Starting in the late 1980s, my ice core research has helped to show that large climate changes tend to occur in the natural system as abrupt and rapid shifts in mode probably driven by internal adjustments in the Earth climate system, rather than slow and gradual adjustments to changing external conditions, such as the amount of energy received from the sun. Shifts of more than 10˚C in mean temperature in less than a human lifetime are common in the paleoclimate record, and serve as a warning that adaptation to future climate changes may not be easy. My research in isotopes in the carbon cycle has also helped to show that land plants are capable of removing large amounts of carbon dioxide from the atmosphere, amounts that equal our input of CO2 from fossil fuel burning on short time scales. Such large changes in the uptake of CO2 by plants is a key piece in the puzzle we must solve to formulate workable policy on CO2 levels and climate change.
- PhD: Columbia University, 1983
- Highly Cited Researcher (2016-2019), Web of Science Group, 2019
- Robert L. Stearns Award, CU Boulder Alumni Association, 2016
- Highly Cited Researcher, Thomson Reuters, 2014
- Fellow, American Association for the Advancement of Science, 2014
- Highly Cited Researcher, ISI, 2001
Research interests: global scale climate and environmental dynamics; carbon dioxide concentrations and climate from stable hydrogen isotopes, peats and other organics; climate from deuterium excess and hydrogen isotopes in ice cores; isotopes in general circulation models; modern carbon cycle dynamics via isotopes of carbon dioxide and methane.
My teaching interests at the undergraduate level focus on human interactions with the environment, as well as general geosciences. I have a strong commitment to undergraduate education in this area, as I believe that an educated citizenry is important in ensuring that reasonable environmental policy is made and implemented. I teach and helped to develop a large lecture class, Introduction to Environmental Studies (ENVS 1000). This course covers the broad spectrum of environmental studies, from the social to the natural sciences. In addition, I developed and teach a large upper level undergraduate course, GEOL 3520, Environmental Issues. This course addresses our present and future energy sources, and how those energy sources affect the Earth’s systems, including climate and biogeochemistry. At the graduate level, I teach courses in my research specialty, stable isotope geochemistry and biogeochemistry. I have also taught the ENVS Honor’s course, and supervised the ENVS Internship Program. I have also been relatively successful in securing funding for education at CU. With a number of other faculty at CU, I have had grants funded by NASA (Earth System Science Education), as well as a multi-million dollar NSF-IGERT graduate training grant. This grant supported 13 graduate students per year for five years in an experiment in team building, disciplinary silo breaking, and co-educating social science, natural science, and journalism graduate students in carbon cycle dynamics, economics and policy.
- ENVS 1000: Introduction to Environmental Studies
- ENVS 3930: Internship in Environmental Studies
- ENVS 4990: Senior Thesis in Environmental Studies
- ENVS 5900: Carbon, Climate, and Society
- ENVS/GEOL 3520: Environmental Issues in Geosciences
- GEOL 1070: Global Change
- GEOL 1110: Global Change Lab
- GEOL 5700: Environmental Isotopes
- GEOL 5700: Current Literature in Global Change Research
Videos about climate change
- Abrupt Impacts of Climate Change: Anticipating surprises
- 120 Seconds of Science with Doc Ryan
- Climate Change Impacts are Happening Faster and Faster