Bio

I am a Stanford Science Fellow and postdoctoral scholar in the Department of Geophysics, working with Ching-Yao Lai. My research explores the connections between landscape dynamics, the global carbon cycle, and climate. I combine field observations, remote sensing, and physical models, often using space-for-time substitutions: natural experiments in which spatial patterns help reveal processes that unfold over timescales too long to observe directly.

At Stanford, I use optical and radar satellite observations to investigate how meltwater drainage beneath the Greenland Ice Sheet controls ice motion and its response to warming. I completed my Ph.D. at Caltech, where I studied how river migration and permafrost shape carbon cycling in Arctic landscapes, alongside projects investigating the controls on mountain erosion and post-wildfire debris flows.

Before Caltech, I worked at the Norwegian Polar Institute, reconstructing 80 years of glacier change across Svalbard to understand how climate and glacier geometry govern ice loss. I earned my B.A. in Geosciences at Princeton, where I combined fieldwork on modern carbonate sediments in the Bahamas with biogeochemical and stratigraphic models to understand how carbonate rocks record ancient sea level and ocean chemistry. This work informs how we read the geological record to reconstruct Earth’s climate and carbon-cycle history.

Honors & Awards

  • Stanford Science Fellowship, Stanford University (2026-2028)
  • Hertz Fellowship, Fannie and John Hertz Foundation (2021-2026)
  • Graduate Research Fellowship, National Science Foundation (2021-2026)
  • Daniel M. Sachs Scholarship, Princeton University (2019-2021)

Professional Education

  • Doctor of Philosophy, California Institute of Technology (2027)
  • Bachelor of Arts, Princeton University (2019)
  • Ph.D., California Institute of Technology, Division of Geological and Planetary Sciences (2026)
  • M.S., California Institute of Technology, Division of Geological and Planetary Sciences (2024)
  • B.A., Princeton University, Department of Geosciences (2019)

Stanford Advisors

Contact

  • Academic
    egeyman@stanford.edu
    University - Scholar Department: Department of Geophysics Position: Postdoctoral Scholar

Additional Info

Links

All Publications

  • Persistent organic carbon storage in river floodplains over millennia. Nature communications Ke, Y., West, A. J., Geyman, E. C., Huy, K. A., Dion-Kirschner, H., Smith, M. I., Anadu, J. S., Magyar, J. S., Lamb, M. P., Fischer, W. W. 2026

    Abstract

    Soils and sediments store a tremendous amount of organic carbon (OC), especially in the Arctic, but its long-term degradation rate remains poorly constrained. Most work estimate terrestrial OC loss from short-term incubation experiments spanning hours to years, even though soils and sediments develop over centuries to millennia. We quantify the changes in OC reactivity and composition across a chronosequence of floodplain deposits in discontinuous permafrost along the Koyukuk River, central Alaska. We observe minimal OC loss over ca. 6000 years, in sharp contrast to the cycling of surface biomass, which decays on decadal timescales in these environments. These results demonstrate that high-latitude permafrost floodplains are efficient carbon reservoirs that trap and preserve organic matter in transient sedimentary archives. The fate of these highly efficacious OC stores depends on the future dynamics of river migration, erosion, and sediment transport-as much as on changes to plant productivity in a warmer climate.

    View details for DOI 10.1038/s41467-026-72405-9

    View details for PubMedID 42045247

  • The contribution of rock strength to soil production NATURE Geyman, E. C., Paige, D. A., Lamb, M. P. 2025; 647 (8091)

    View details for DOI 10.1038/s41586-025-09751-z

    View details for Web of Science ID 001613210000001

  • Scaling laws for sediment storage and turnover in river floodplains SCIENCE ADVANCES Geyman, E. C., Ke, Y., Magyar, J. S., Reahl, J. N., Soldano, V., Brown, N. D., West, A., Fischer, W. W., Lamb, M. P. 2025; 11 (15)

    View details for DOI 10.1126/sciadv.adu8574

    View details for Web of Science ID 001464913900024

  • Permafrost slows Arctic riverbank erosion. Nature Geyman, E. C., Douglas, M. M., Avouac, J. P., Lamb, M. P. 2024; 634 (8033): 359-365

    Abstract

    The rate of river migration affects the stability of Arctic infrastructure and communities1,2 and regulates the fluxes of carbon3,4, nutrients5 and sediment6,7 to the oceans. However, predicting how the pace of river migration will change in a warming Arctic8 has so far been stymied by conflicting observations about whether permafrost9 primarily acts to slow10,11 or accelerate12,13 river migration. Here we develop new computational methods that enable the detection of riverbank erosion at length scales 5-10 times smaller than the pixel size in satellite imagery, an innovation that unlocks the ability to quantify erosion at the sub-monthly timescales when rivers undergo their largest variations in water temperature and flow. We use these high-frequency observations to constrain the extent to which erosion is limited by the thermal condition of melting the pore ice that cements bank sediment14, a requirement that will disappear when permafrost thaws, versus the mechanical condition of having sufficient flow to transport the sediment comprising the riverbanks, a condition experienced by all rivers15. Analysis of high-resolution data from the Koyukuk River, Alaska, shows that the presence of permafrost reduces erosion rates by 47%. Using our observations, we calibrate and validate a numerical model that can be applied to diverse Arctic rivers. The model predicts that full permafrost thaw may lead to a 30-100% increase in the migration rates of Arctic rivers.

    View details for DOI 10.1038/s41586-024-07978-w

    View details for PubMedID 39385050

    View details for PubMedCentralID 6289964

  • The origin of carbonate mud and implications for global climate. Proceedings of the National Academy of Sciences of the United States of America Geyman, E. C., Wu, Z., Nadeau, M. D., Edmonsond, S., Turner, A., Purkis, S. J., Howes, B., Dyer, B., Ahm, A. C., Yao, N., Deutsch, C. A., Higgins, J. A., Stolper, D. A., Maloof, A. C. 2022; 119 (43): e2210617119

    Abstract

    Carbonate mud represents one of the most important geochemical archives for reconstructing ancient climatic, environmental, and evolutionary change from the rock record. Mud also represents a major sink in the global carbon cycle. Yet, there remains no consensus about how and where carbonate mud is formed. Here, we present stable isotope and trace-element data from carbonate constituents in the Bahamas, including ooids, corals, foraminifera, and algae. We use geochemical fingerprinting to demonstrate that carbonate mud cannot be sourced from the abrasion and mixture of any combination of these macroscopic grains. Instead, an inverse Bayesian mixing model requires the presence of an additional aragonite source. We posit that this source represents a direct seawater precipitate. We use geological and geochemical data to show that "whitings" are unlikely to be the dominant source of this precipitate and, instead, present a model for mud precipitation on the bank margins that can explain the geographical distribution, clumped-isotope thermometry, and stable isotope signature of carbonate mud. Next, we address the enigma of why mud and ooids are so abundant in the Bahamas, yet so rare in the rest of the world: Mediterranean outflow feeds the Bahamas with the most alkaline waters in the modern ocean (>99.7th-percentile). Such high alkalinity appears to be a prerequisite for the nonskeletal carbonate factory because, when Mediterranean outflow was reduced in the Miocene, Bahamian carbonate export ceased for 3-million-years. Finally, we show how shutting off and turning on the shallow carbonate factory can send ripples through the global climate system.

    View details for DOI 10.1073/pnas.2210617119

    View details for PubMedID 36252022

    View details for PubMedCentralID PMC9618081

  • Historical glacier change on Svalbard predicts doubling of mass loss by 2100 NATURE Geyman, E. C., van Pelt, W. J. J., Maloof, A. C., Aas, H., Kohler, J. 2022; 601 (7893): 374-+

    View details for DOI 10.1038/s41586-021-04314-4

    View details for Web of Science ID 000744666700029

  • Facies control on carbonate 813C on the Great Bahama Bank GEOLOGY Geyman, E. C., Maloof, A. C. 2021; 49 (9): 1049-1054

    View details for DOI 10.1130/G48862.1

    View details for Web of Science ID 000692563800010

  • A diurnal carbon engine explains <SUP>13</SUP>C-enriched carbonates without increasing the global production of oxygen PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Geyman, E. C., Maloof, A. C. 2019; 116 (49): 24433-24439

    View details for DOI 10.1073/pnas.1908783116

    View details for Web of Science ID 000500804600015

https://orcid.org/0000-0003-4349-9350