Scott J. Lehman

Senior Research Associate • 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.

Recent publications

ATMOSPHERIC RADIOCARBON FOR THE PERIOD 1950-2019

CU Boulder Authors: Lehman, Scott J; Turnbull, Jocelyn Christine

All Authors:

Hua Q; Turnbull JC; Santos GM; Rakowski AZ; Ancapichun S; De Pol-Holz R; Hammer S; Lehman SJ; Levin I; Miller JB...

Hua Q
Turnbull JC
Santos GM
Rakowski AZ
Ancapichun S
De Pol-Holz R
Hammer S
Lehman SJ
Levin I
Miller JB

Published in: Radiocarbon: an international journal of cosmogenic isotope research
Publication Date: 2021-11-23
Type: Journal Article

Large and seasonally varying biospheric CO2 fluxes in the Los Angeles megacity revealed by atmospheric radiocarbon

CU Boulder Authors: Lehman, Scott J

All Authors: Miller JB; Lehman SJ; Verhulst KR; Miller CE; Duren RM; Yadav V; Newman S; Sloop CD

Published in: Proceedings of the National Academy of Sciences of USA
Publication Date: 2020-10-27
Type: Journal Article

Observations of atmospheric (CO2)-C-14 at Anmyeondo GAW station, South Korea: implications for fossil fuel CO2 and emission ratios

CU Boulder Authors: Petron, Gabrielle; Turnbull, Jocelyn Christine; Lehman, Scott J

All Authors:

Lee H; Dlugokencky EJ; Turnbull JC; Lee S; Lehman SJ; Miller JB; Petron G; Lim J-S; Lee G-W; Lee S-S...

Lee H
Dlugokencky EJ
Turnbull JC
Lee S
Lehman SJ
Miller JB
Petron G
Lim J-S
Lee G-W
Lee S-S

Published in: Atmospheric Chemistry and Physics
Publication Date: 2020-10-26
Type: Journal Article

Estimating US fossil fuel CO2 emissions from measurements of C-14 in atmospheric CO2

CU Boulder Authors: Lehman, Scott J

All Authors: Basu S; Lehman SJ; Miller JB; Andrews AE; Sweeney C; Gurney KR; Xu X; Southon J; Tans PP

Published in: Proceedings of the National Academy of Sciences of USA
Publication Date: 2020-06-16
Type: Journal Article

The Dating of a Middle Paleolithic Blade Industry in Southern Russia and Its Relationship to the Initial Upper Paleolithic

CU Boulder Authors: Hoffecker, John Frank; Lehman, Scott J

All Authors:

Hoffecker JF; Holliday VT; Nehoroshev P; Vishnyatsky L; Otcherednoy A; Salnaya N; Goldberg P; Southon J; Lehman SJ; Capp...

Hoffecker JF
Holliday VT
Nehoroshev P
Vishnyatsky L
Otcherednoy A
Salnaya N
Goldberg P
Southon J
Lehman SJ
Cappa PJ

Publication Date: 2019-12-01
Type: Journal Article

Atmospheric observation-based estimation of fossil fuel CO2 emissions from regions of central and southern California

CU Boulder Authors: Lehman, Scott J

All Authors: Cui X; Newman S; Xu X; Andrews AE; Miller J; Lehman S; Jeong S; Zhang J; Priest C; Campos-Pineda M

Published in: Science of the Total Environment
Publication Date: 2019-05-10
Type: Journal Article

Rapidly receding Arctic Canada glaciers revealing landscapes continuously ice-covered for more than 40,000 years

CU Boulder Authors: Miller, Gifford H; Anderson, Bob; Lehman, Scott J

All Authors: Pendleton SL; Miller GH; Lifton N; Lehman SJ; Southon J; Crump SE; Anderson RS

Published in: Nature Communications
Publication Date: 2019-01-25
Type: Journal Article

Synthesis of Urban CO2 Emission Estimates from Multiple Methods from the Indianapolis Flux Project (INFLUX)

CU Boulder Authors: Turnbull, Jocelyn Christine; Lehman, Scott J

All Authors:

Turnbull JC; Karion A; Davis KJ; Lauvaux T; Miles NL; Richardson SJ; Sweeney C; McKain K; Lehman SJ; Gurney KR...

Turnbull JC
Karion A
Davis KJ
Lauvaux T
Miles NL
Richardson SJ
Sweeney C
McKain K
Lehman SJ
Gurney KR

Published in: Environmental Science and Technology (Washington)
Publication Date: 2019-01-01
Type: Journal Article

Assessing fossil fuel CO2 emissions in California using atmospheric observations and models

CU Boulder Authors: Lehman, Scott J; Michelsen, Hope A.

All Authors:

Graven H; Fischer ML; Lueker T; Jeong S; Guilderson TP; Keeling RF; Bambha R; Brophy K; Callahan W; Cui X...

Graven H
Fischer ML
Lueker T
Jeong S
Guilderson TP
Keeling RF
Bambha R
Brophy K
Callahan W
Cui X

Published in: Environmental Research Letters
Publication Date: 2018-06-01
Type: Journal Article

Limited contribution of ancient methane to surface waters of the U.S. Beaufort Sea shelf

CU Boulder Authors: Lehman, Scott J

All Authors:

Sparrow KJ; Kessler JD; Southon JR; Garcia-Tigreros F; Schreiner KM; Ruppel CD; Miller JB; Lehman SJ; Xu X...

Sparrow KJ
Kessler JD
Southon JR
Garcia-Tigreros F
Schreiner KM
Ruppel CD
Miller JB
Lehman SJ
Xu X

Published in: Science Advances
Publication Date: 2018-01-01
Type: Journal Article

Considerable contribution of the Montreal Protocol to declining greenhouse gas emissions from the United States

CU Boulder Authors: Hu, Lei; Lehman, Scott J

All Authors:

Hu L; Montzka SA; Lehman SJ; Godwin DS; Miller BR; Andrews AE; Thoning K; Miller JB; Sweeney C; Siso C...

Hu L
Montzka SA
Lehman SJ
Godwin DS
Miller BR
Andrews AE
Thoning K
Miller JB
Sweeney C
Siso C

Published in: Geophysical Research Letters
Publication Date: 2017-08-16
Type: Journal Article

COMPATIBILITY OF ATMOSPHERIC (CO2)-C-14 MEASUREMENTS: COMPARING THE HEIDELBERG LOW-LEVEL COUNTING FACILITY TO INTERNATIONAL ACCELERATOR MASS SPECTROMETRY (AMS) LABORATORIES

CU Boulder Authors: Turnbull, Jocelyn Christine; Lehman, Scott J

All Authors:

Hammer S; Friedrich R; Kromer B; Cherkinsky A; Lehman SJ; Meijer HAJ; Nakamura T; Palonen V; Reimer RW; Smith AM...

Hammer S
Friedrich R
Kromer B
Cherkinsky A
Lehman SJ
Meijer HAJ
Nakamura T
Palonen V
Reimer RW
Smith AM

Published in: Radiocarbon: an international journal of cosmogenic isotope research
Publication Date: 2017-06-01
Type: Journal Article

John Trevor Hollin 1930-2016

CU Boulder Authors: Lehman, Scott J

All Authors: Lehman SJ; Andrews JT

Published in: Arctic, Antarctic, and Alpine Research
Publication Date: 2017-05-01
Type: Journal Article

Humans rather than climate the primary cause of Pleistocene megafaunal extinction in Australia

CU Boulder Authors: Lehman, Scott J; Miller, Gifford H

All Authors: van der Kaars S; Miller GH; Turney CSM; Cook EJ; Nuernberg D; Schoenfeld J; Kershaw AP; Lehman SJ

Published in: Nature Communications
Publication Date: 2017-01-20
Type: Journal Article

Episodic Neoglacial snowline descent and glacier expansion on Svalbard reconstructed from the C-14 ages of ice-entombed plants

CU Boulder Authors: Miller, Gifford H; Lehman, Scott J

All Authors: Miller GH; Landvik JY; Lehman SJ; Southon JR

Published in: Quaternary Science Reviews: the international multidisciplinary research and review journal
Publication Date: 2017-01-01
Type: Journal Article

Atmospheric monitoring of carbon capture and storage leakage using radiocarbon

CU Boulder Authors: Turnbull, Jocelyn Christine; Lehman, Scott J

All Authors: Turnbull JC; Keller ED; Norris MW; Wiltshire RM

Published in: International Journal of Greenhouse Gas Control
Publication Date: 2017-01-01
Type: Journal Article

Strong regional atmospheric C-14 signature of respired CO2 observed from a tall tower over the midwestern United States

CU Boulder Authors: Turnbull, Jocelyn Christine; Lehman, Scott J

All Authors:

LaFranchi BW; McFarlane KJ; Miller JB; Lehman SJ; Phillips CL; Andrews AE; Tans PP; Chen H; Liu Z; Turnbull JC...

LaFranchi BW
McFarlane KJ
Miller JB
Lehman SJ
Phillips CL
Andrews AE
Tans PP
Chen H
Liu Z
Turnbull JC

Published in: Journal of Geophysical Research: Biogeosciences
Publication Date: 2016-08-01
Type: Journal Article

New constraints on deglacial marine radiocarbon anomalies from a depth transect near Baja California

CU Boulder Authors: Lehman, Scott J; Marchitto, Tom

All Authors: Lindsay CM; Lehman SJ; Marchitto TM; Carriquiry JD; Ortiz JD

Published in: Paleoceanography
Publication Date: 2016-08-01
Type: Journal Article

The surface expression of radiocarbon anomalies near Baja California during deglaciation (vol 422, pg 67, 2015)

CU Boulder Authors: Lehman, Scott J; Marchitto, Tom

All Authors: Lindsay CM; Lehman SJ; Marchitto TM; Ortiz JD

Published in: Earth and Planetary Science Letters
Publication Date: 2016-05-15
Type: Journal Article

Continued emissions of carbon tetrachloride from the United States nearly two decades after its phaseout for dispersive uses

CU Boulder Authors: Dutton, Geoffrey; Lehman, Scott J; de Gouw, Joost; Moore, Fred Lee; Hu, Lei

All Authors:

Hu L; Montzka SA; Miller BR; Andrews AE; Miller JB; Lehman SJ; Sweeney C; Miller SM; Thoning K; Siso C...

Hu L
Montzka SA
Miller BR
Andrews AE
Miller JB
Lehman SJ
Sweeney C
Miller SM
Thoning K
Siso C

Published in: Proceedings of the National Academy of Sciences of USA
Publication Date: 2016-03-15
Type: Journal Article

Separation of biospheric and fossil fuel fluxes of CO2 by atmospheric inversion of CO2 and 14CO2 measurements: Observation System Simulations

CU Boulder Authors: Lehman, Scott J

All Authors: Basu S; Miller JB; Lehman S

Published in: Atmospheric Chemistry and Physics Discussions
Publication Date: 2016-01-21
Type: Journal Article

Human predation contributed to the extinction of the Australian megafaunal bird Genyornis newtoni similar to 47 ka

CU Boulder Authors: Lehman, Scott J; Miller, Gifford H

All Authors: Miller G; Magee J; Smith M; Spooner N; Baynes A; Lehman S; Fogel M; Johnston H; Williams D; Clark P

Published in: Nature Communications
Publication Date: 2016-01-01
Type: Journal Article

Radiocarbon evidence for a possible abyssal front near 3.1 km in the glacial equatorial Pacific Ocean

CU Boulder Authors: Lehman, Scott J

All Authors: Keigwin LD; Lehman SJ

Published in: Earth and Planetary Science Letters
Publication Date: 2015-09-01
Type: Journal Article

The surface expression of radiocarbon anomalies near Baja California during deglaciation

CU Boulder Authors: Marchitto, Tom; Lehman, Scott J

All Authors: Lindsay CM; Lehman SJ; Marchitto TM; Ortiz JD

Published in: Earth and Planetary Science Letters
Publication Date: 2015-07-15
Type: Journal Article

Observations of (CO2)-C-14 in ecosystem respiration from a temperate deciduous forest in Northern Wisconsin

CU Boulder Authors: Lehman, Scott J

All Authors: Phillips CL; McFarlane KJ; LaFranchi B; Desai AR; Miller JB; Lehman SJ

Published in: Journal of Geophysical Research: Biogeosciences
Publication Date: 2015-04-01
Type: Journal Article

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

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Outreach

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News

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.

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Scott J. Lehman

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