Scott J. Lehman

Fellow Emeritus • Director, Laboratory for AMS Radiocarbon Preparation and Research (NSRL) •
• Paleoclimatology • Paleoceanography • Radiocarbon research

scott.lehman@colorado.edu

303 492-8980

Center for the Geochemical Analysis of the Global Environment (GAGE)

AMS Radiocarbon Lab

Bio

Originally trained in Quaternary and glacial geology, my interests turned to oceanography after noting the profound influence of ocean heat transport on ice sheet growth and retreat in the Arctic. I was amongst the first to show that the timing and speed of changes in the large scale overturning circulation of the oceans matched that predicted by paleo-temperature records from Greenland ice cores and (the then) nascent numerical models of ocean circulation. In the run-up to the 1992 Rio Earth Summit (at which the United Nations Framework Convention on Climate Change was opened for signing) I gave testimony to the U.S. Senate warning that unmitigated warming could lead to changes in the overturning circulation of the northern North Atlantic—a phenomenon now clearly visible in regional air and sea temperatures 25 years later. For the last two decades my work has focused on studies of the ocean’s role in determining Ice Age (natural) CO₂ variations and on the use of ¹⁴C as a tracer in the contemporary carbon cycle and for direct quantification of anthropogenic CO₂emissions.

Education

PhD: University of Colorado, 1989
Postdoctoral Scholar: Woods Hole Oceanographic Inst/MIT Joint Program in Oceanography, 1987

Research

The role of the oceans in climate change; cycling of heat, fresh water, and carbon by the oceans; dynamics and consequences of abrupt climate change; radiocarbon dating; 14C as a tracer in the carbon cycle.

Watch a 19-min video presentation on estimating US CO2 emissions
(CU-NOAA ¹⁴C-based Inverse Estimation of US CO₂ emissions, EGU 2021)

Resources

Publications

Select publications

2020: Basu, S., Lehman, S. J., Miller, J. B., Andrews, A. E., Sweeney, C., Gurney, K., Xu, X., Southon, J., Tans, P. P. Estimating US fossil fuel CO₂ emissions from measurements of ¹⁴C in atmospheric CO₂. Proceedings of the National Academy of Sciences, 117(24). doi 10.1073/pnas.1919032117

2016: Basu, S., Miller, J. B., Lehman, S. J. Separation of biospheric and fossil fuel fluxes of CO₂ by atmospheric inversion of CO₂ and ¹⁴CO₂ measurements: Observation System Simulations. Atmospheric Chemistry and Physics, 16: 5665-5683. doi 10.5194/acp-16-5665-2016

2012: Miller, J. B., Lehman, S. J., Montzka, S. A., Sweeney, C., Miller, B. R., Karion, A., Wolak, C., Dlugokencky, E. J., Southon, J., Turnbull, J. C., Tans, P. P. Linking emissions of fossil fuel CO₂ and other anthropogenic trace gases using atmospheric ¹⁴CO₂. Journal of Geophysical Research—Atmospheres, 117(D8). doi 10.1029/2011JD017048

2007: Marchitto, T. M., Lehman, S. J., Ortiz, J. D., Flueckiger, J., van Geen, A. Marine radiocarbon evidence for the mechanism of deglacial atmospheric CO₂ rise. Science, 316(5830): 1456-1459. doi 10.1126/science.1138679

2007: Turnbull, J. C., Lehman, S. J., Miller, J. B., Sparks, R. J., Southon, J. R., Tans P. P. A new high precision ¹⁴CO₂ time series for North American continental air. Journal of Geophysical Research—Atmospheres, 112(D11). doi 10.1029/2006JD008184

2004: Hughen, K., Lehman, S., Southon, J., Overpeck, J., Marchal, O., Herring, C., Turnbull, J. C-14 activity and global carbon cycle changes over the past 50,000 years. Science, 303(5655) 202-207. doi 10.1126/science.1090300

2000: Hughen, K. A., Southon, J. R., Lehman, S. J., Overpeck, J. T. Synchronous radiocarbon and climate shifts during the last deglaciation. Science, 290(5498): 1951-1954. doi 10.1126/science.290.5498.1951

1993: Oppo, D. W., Lehman, S. J. Mid-depth circulation of the subpolar North Atlantic during the last glacial maximum. Science, 259(5098): 1148-1152. doi 10.1126/science.259.5098.1148

1992: Lehman, S. J., Keigwin, L. D. Sudden changes in North Atlantic circulation during the last deglaciation. Nature, 356(6372): 757-762. doi 10.1038/356757a0

All publications

For a full list of Scott's publications, see his Google Scholar profile.

Teaching

Current courses

GEOL 5420: Quaternary Dating Methods

Past courses

GEOL 5700-011: Super-Problems in Quaternary Climate
GEOL 5845-900: Independent Study, Geochemistry
GEOL/ENVS 352: Environmental Issues in the Geosciences

Current postdoc

Michael Dyonisius

Postdoctoral Scholar •
• Ice core trace gases

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Outreach

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News

Simon Pendleton and Giff Miller collect ancient plant remains melted out of the edges of the ice cap on Baffin Island. Photo by Matt Kennedy, Earth Vision Trust.

Kirk Bryan Award goes to a team of INSTAARs, colleagues

Oct. 19, 2023

A team of researchers that included several INSTAAR scientists received the prestigious Kirk Bryan Award from the Quaternary Geology & Geomorphology Division of the Geological Society of America (GSA). The prestigious award honors the authors of a recent paper that advances the science of geomorphology.

An aerial view of trees and the Los Angeles Country Club golf course, parts of Los Angeles' urban ecosystem.

Lawns and landscaping complicate taking the measure of Los Angeles Basin’s carbon footprint

Oct. 12, 2020

The Los Angeles Basin is often thought of as a dry, heavily developed landscape. But a new study in PNAS led by NOAA and the University of Colorado Boulder shows that the manicured lawns, emerald golf courses, and trees of America’s second-largest city play a surprisingly large role in its carbon footprint.

INSTAAR Chad Wolak prepares air samples for carbon-14 measurement. Photo by Scott Lehman.

Radioactive bookkeeping of carbon emissions (Eos)

June 24, 2020

A new sampling method uses carbon-14 to single out which carbon dioxide molecules in the atmosphere derive from fossil fuels. The method could help track emissions goals for climate mitigation.

Chad Wolak prepares NOAA air samples for carbon-14 measurement.

Tracking fossil fuel emissions with carbon-14

June 1, 2020

Researchers from NOAA and the University of Colorado have devised a breakthrough method for estimating national emissions of carbon dioxide from fossil fuels using ambient air samples and a well-known isotope of carbon scientists have relied on for decades to date archaeological sites. In a paper published in Proceedings of the National Academy of Sciences, they report the first-ever national scale estimate of fossil-fuel derived carbon dioxide (CO2) emissions obtained by observing CO2 and its naturally occurring radioisotope, carbon-14, from air samples collected by NOAA’s Global Greenhouse Gas Reference Network.

More Lehman news

Scott J. Lehman