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Climate Change Institute

Aaron Putnam

Assistant Professor, School of Earth and Climate Sciences & Climate Change Institute

Aaron Putnam

Contact Information



224 Bryand Global Sciences Ctr.
University of Maine 
Orono, ME  04469

Research interests

I am interested in mechanisms of Late Quaternary climate change.  In particular, the causes of the 100,000-yr glacial cycles of the past million years, and the abrupt climate switches that brought them to a close, remain fundamental outstanding problems.  I am also interested in the underlying causes of natural climate variations over the Holocene, and their associations with the rise and fall of civilizations.  The effects of ice ages, abrupt climate change, and Holocene climate variability have been imprinted on the landscape by Earth's mountain glaciers, ice sheets, and pluvial lake systems. I am attempting to construct the evolution of these climate switches by developing precise chronologies of glacier and pluvial lake activity in the middle latitudes of the polar hemispheres.  I use surface-exposure and radiocarbon dating techniques to construct chronologies of glacial landforms that mark past extents of mountain glaciers and ice sheets.  Working together with Sean Birkel, I employ geometrical snowline reconstruction and glaciological modeling techniques to derive quantitative paleoclimatic information from glacier landforms. We are interested in how abrupt climate anomalies are transmitted between the hemispheres during glacial terminations, and more recently during Medieval time and the 'Little Ice Age'.  We are also interested in the role of radiative forcing in glacial cycles.  For example, we are currently merging our glacial chronology data from the western United States and interior Asia with glaciological and energy-balance modeling to derive the role of total radiative forcing in producing Northern Hemisphere glaciations.  A solution to this problem can inform regional solutions for the sensitivity of atmospheric temperatures to elevated atmospheric CO2 concentrations.

Another fundamental problem of climate research involves how Earth's water resources will respond to global warming, as well as future natural climate variations.  In this regard, I work with a team from the University of Nevada, Reno, led by Professor Douglas Boyle, as well as John Chiang at UC Berkeley, to merge paleohydrological lake-level information with sophisticated hydrological modeling in order to assess (1) how dryland hydroclimates responded to past climate shifts, and (2) potential impacts of ongoing and future warming on water resources in Northern Hemisphere drylands.  Sean Birkel is also involved in this effort.  We are integrating paleohydrological solutions with our mountain glacier research to deconvolve atmospheric temperature and precipitation evolution of the western United States and interior Asia since the last ice age.

Field areas include:

Southern Alps, New Zealand (with George Denton and Joerg Schaefer)

Patagonian Andes (with Charlie Porter, Brenda Hall, George Denton, and Tom Lowell)

Rocky Mountains and Sierra Nevada, western USA (with Sean Birkel, David Putnam, George Denton, Joerg Schaefer, Doug Boyle, Scott Bassett)

Tarim Basin, Xinjiang, China (with Wally Broecker, George Denton, David Putnam, Chunzeng Wang, Ed Cook, and Jonathan Palmer)

Mongolian Altai (with Olaf Jensen, David Putnam, and Joerg Schaefer)

Bhutan Himalaya (with Joerg Schaefer, Ed Cook, and Summer Rupper)

Scottish Highlands (with Gordon Bromley and Kurt Rademaker)

western Norway (with Bjørn Andersen)

Switzerland (with Joerg Schaefer)

Midwestern United States (with Tom Lowell)

Previous field areas: northern Maine, northern Alaska, the Canadian Arctic Archipelago, and the Transantarctic Mountains, Antarctica.



  • Putnam, A.E., Putnam, D.E., Andreu-Hayles, L., Cook, E.R., Palmer, J.D., Clark, E.H., Wang, C., Chen, F., Denton, G.H., Boyle, D.P., Bassett, S.D., Birkel, S.D., Martin-Fernandez, J., Hajdas, I., Southon, J, Garner, C.B., Cheng, H., and Broecker, W.S., 2016. Little Ice Age wetting of interior Asian deserts and the rise of the Mongol Empire. Quaternary Science Reviews 131, 33-50.
  • Hatchett, B.J., Boyle, D. P., Putnam, A.E., Bassett, S.D., 2015. Placing the 2012-2015 California-Nevada drought into a paleoclimatic context. Geophysical Research Letters 42, 8632-8640.

Additional Publications

  • Putnam, A.E., 2015. A glacial zephyr. Nature Geoscience 8, 175-176.
  • Schaefer, J.M., Putnam, A.E., Denton, G.H., Kaplan, M.R., Doughty, A., Kelley, S.E., Barrell, D.J.A., Finkel, R.C., Winckler, G., Anderson, R.F., Ninnemann, U.S., Barker, S., Schluechter, C., 2015. The Southern Glacial Maximum 65,000 years ago and its Unfinished Termination. Quaternary Science Reviews 114, 52-60.
  • Doughty, A.M., Schaefer, J.M., Putnam, A.E., Denton, G.H., Kaplan, M.R., Barrell, D.J.A., Andersen, B.G., Kelley, S.E., Finkel, R.C., Schwartz, R., 2015. Mismatch of glacier extent and summer insolation in Southern Hemisphere mid-latitudes. Geology 43, 407-410.
  • Krusic, P.J., Cook, E.R., Dukpa, D., Putnam, A.E., Rupper, S., Schaefer, J.S., 2015. Six hundred thirty-eight years of summer temperature variability over the Bhutanese Himalaya. Geophysical Research Letters 42, 2988-2994.
  • Moreno, P.I., Denton, G.H., Moreno, H., Kaplan, M.R., Putnam, A.E., 2015. Radiocarbon chronology of the last glacial maximum and its termination in northwestern Patagonia. Quaternary Science Reviews 122, 233-249.
  • Broecker, W.S., Yu, J., Putnam, A.E., 2015. Two contributors to the glacial CO2 decline. Earth and Planetary Science Letters 429, 191-196.
  • Moreno, P.I., Denton, G.H., Moreno, H., Kaplan, M.R., Putnam, A.E., 2015. Radiocarbon chronology of the last glacial maximum and its termination in northwestern Patagonia. Quaternary Science Reviews 122, 233-249.
  • Bromley, G.R.M., Putnam, A.E., Rademaker, K.M., Lowell, T.V., Schaefer, J.M., Hall, B.L., Winckler, G., Birkel, S.D., Borns, H.W., 2014. Younger Dryas deglaciation of Scotland driven by warming summers. Proceedings of the National Academy of Sciences 111, 6215-6219.
  • Chiang, J.C.H., Lee, S.-Y., Putnam, A.E., Wang, X., 2014. South Pacific Split Jet, ITCZ shifts, and atmospheric North-South linkages during abrupt climate changes of the last glacial period. Earth and Planetary Science Letters 406, 233-246.
  • Kelley, S.E., Kaplan, M.R., Schaefer, J.M., Andersen, B.G., Barrell, D.J.A., Putnam, A.E., Denton, G.H., Schwartz, R., Finkel, R.C., Doughty, A.M., 2014. High-precision 10Be chronology of moraines in the Southern Alps indicates synchronous cooling in Antarctica and New Zealand 42,000 years ago. Earth and Planetary Science Letters 405, 194-206.
  • Schimmelpfenig, I., Schaefer, J.M., Putnam, A.E., Koffman, T., Benedetti, L., Ivy-Ochs, S., ASTER team, Schlüchter, C., 2014. 36Cl production rate from K-spallation in the European Alps (Chironico landslide, Switzerland). Journal of Quaternary Science 29, 407-413.
  • Kaplan, M.R., Schaefer, J.M., Denton, G.H., Doughty, A.M., Barrell, D.J.A., Chinn, T.J.H., Putnam, A.E., Andersen, B.G., Mackintosh, A., Finkel, R.C., Schwartz, R., Anderson, B., 2013. The anatomy of long-term warming since 15 ka in New Zealand based on net glacier snowline rise. Geology 41, 887-890.
  • Putnam, A.E., Schaefer, J.M., Denton, G.H., Barrell, D.J.A., Sean D. Birkel, Kaplan, M.R., Andersen, B.G., Finkel, R.C., Schwartz, R., Doughty, A.M., 2013. The last glacial maximum at 44°S documented by a 10Be moraine chronology at Lake Ohau, Southern Alps of New Zealand. Quaternary Science Reviews 62, 114-141.
  • Ackert, R.P., Jr., Putnam, A.E., Mukhopadhyay, S., Pollard, D., DeConto, R.M., Kurz, M.D., Borns, H.W., Jr., 2013. Controls on interior West Antarctic Ice Sheet elevations: Inferences from geologic constraints and ice sheet modeling. Quaternary Science Reviews 65, 26-38.
  • Broecker, W.S., Putnam, A.E., 2013. Hydrologic impacts of past shifts of Earth's thermal equator offer insight into those to be produced by fossil fuel CO2. Proceedings of the National Academy of Sciences 110, 16710-16715.
  • Putnam, A.E., Schaefer, J.M., Denton, G.H., Barrell, D.J.A., Andersen, B.G., Koffman, T.N.B.K., Rowan, A.V., Finkel, R.C., Rood, D.H., Schwartz, R., Vandergoes, M.J., Plummer, M.A., Brocklehurst, S.H., Kelley, S.E., Ladig, K.L., 2013. Warming and glacier recession in the Rakaia valley, Southern Alps of New Zealand, during Heinrich Stadial 1. Earth and Planetary Science Letters 382, 98-110.
  • Birkel, S.D., Putnam, A.E., Denton, G.H., Koons, P.O., Fastook, J.L., Maasch, K.A., Putnam, D.E., 2012. Climate inferences from a glaciological reconstruction of the Late Pleistocene Wind River Ice Cap, Wind River Range, Wyoming. Arctic, Antarctic, and Alpine Research 44, 265-276.
  • Putnam, A.E., Schaefer, J.M., Denton, G.H., Barrell, D.J.A., Andersen, B.G., Schwartz, R., Chinn, T.J.H., Doughty, A.M., 2012. Regional climate control of glaciers in New Zealand and Europe during the pre-industrial Holocene. Nature Geoscience 5, 627-630.
  • Schimmelpfennig, I., Schaefer, J.M., Goehring, B.M., Lifton, N., Putnam, A.E., Barrell, D.J.A., 2012. Calibration of the in situ cosmogenic 14C production rate in New Zealand’s Southern Alps. Journal of Quaternary Science 27, 671-674.
  • Doughty, A.M., Anderson, B.M., Mackintosh, A.N., Kaplan, M.R., Vandergoes, M.J., Chinn, T.J.H., Barrell, D.J.A., Denton, G.H., Schaefer, J.M., Putnam, A.E. Evaluation of Lateglacial temperatures in the Southern Alps of New Zealand based on glacier modelling at Irishman Stream, Ben Ohau Range. Quaternary Science Reviews 74, 160-169.
  • Broecker, W.S., Putnam, A.E., 2012. How did the hydrological cycle respond to the two-phase mystery interval? Quaternary Science Reviews 57, 17-25.
  • Strelin, J.A., Denton, G.H., Vandergoes, M.J., Ninnemann, U.S., Putnam, A.E. Radiocarbon chronology of the late-glacial Puerto Bandera moraines, southern Patagonian Icefield, Argentina. Quaternary Science Reviews 30, 2551-2569.
  • Ackert, R.P., Jr., Mukhopadhyay, S., Pollard, D., DeConto, R.M., Putnam, A.E., Borns, H.W., Jr., 2011. West Antarctic Ice Sheet elevations in the Ohio Range: Geological constraints and ice sheet modeling prior to the last highstand. Earth and Planetary Science Letters 307, 83-93.
  • Kaplan, M.R., Strelin, J.A., Schaefer, J.M., Denton, G.H., Finkel, R.C., Schwartz, R., Putnam, A.E., Vandergoes, M.J., Goehring, B.M., Travis, S.G., 2011. In-situ cosmogenic 10Be production rate at Lago Argentino, Patagonia: Implications for late-glacial climate chronology. Earth and Planetary Science Letters 309, 21-32.
  • Barker, S., Knorr, G., Edwards, R.L., Perrenin, F., Putnam, A.E., Skinner, L.C., Wolff, E., Ziegler, M., 2011. 800,000 Years of Abrupt Climate Variability. Science 334, 338-351.
  • Putnam, A.E., Schaefer, J.M., Barrell, D.J.A., Vandergoes, M., Denton, G.H., Kaplan, M.R., Finkel, R.C., Schwartz, R., Goehring, B.M., Kelley, S.E., 2010. In situ cosmogenic 10Be production-rate calibration from the Southern Alps, New Zealand. Quaternary Geochronology 5, 392-409.
  • Siddall, M., Kaplan, M.R., Schaefer, J.M., Putnam, A.E., Kelly, M.A., Goehring, B., 2010. Changing influence of Antarctic and Greenlandic temperature records on sea-level over the last glacial cycle. Quaternary Science Reviews 29, 410-423.
  • Broecker, W.S., Denton, G.H., Edwards, R.L., Cheng, H., Alley, R.B., Putnam, A.E., 2010. Putting the Younger Dryas cold event into context. Quaternary Science Reviews 29, 1078-1081.
  • Denton, G.H., Anderson, R.F., Toggweiler, J.R., Edwards, R.L., Schaefer, J.M., Putnam, A.E., 2010. The last glacial termination. Science 238, 1652-1656.
  • Kaplan, M.R., Schaefer, J.M., Denton, G.H., Barrell, D.J.A., Chinn, T.J.H., Putnam, A.E., Andersen, B.G., Finkel, R.C., Schwartz, R., Doughty, A.M., 2010. Glacier retreat in New Zealand during the Younger Dryas stadial. Nature 467, 194-197.
  • Putnam, A.E., Denton, G.H., Schaefer, J.M., Barrell, D.J.A., Andersen, B.G., Finkel, R.C., Schwartz, R., Doughty, A.M., Kaplan, M.R., 2010. Glacier advance in southern middle-latitudes during the Antarctic Cold Reversal. Nature Geoscience, doi:10.1038/ngeo962
  • Putnam, A.E., and Putnam, D.E., 2009. Inactive and relict rock glaciers of the Deboullie Lakes Ecological Reserve, northern Maine, USA. Journal of Quaternary Science 24, 773-784.
  • Schaefer, J.M., Denton, G.H., Kaplan, M., Putnam, A., Finkel, R.C., Barrell, D.J.A., Andersen, B.G., Schwartz, R., Mackintosh, A., Chinn, T., Schlüchter, C., 2009. High-frequency Holocene glacier fluctuations in New Zealand differ from the northern signature. Science 324, 622-625.


Ph.D. University of Maine; M.S. University of Maine, B.S. Bates College

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