Tél. : 01.69.08.39.56
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I am a Research Scientist in the Paleoceanography group at LSCE. I use the chemical composition of foraminifera (small marine calcifiers) to understand past climate change. I am responsible for the foraminiferal trace element lab at LSCE. Please get in touch with any enquiries.
A complete publication list is available on Google Scholar.
Follow me on Blue Sky @willerstorfi.bsky.social
A web app version of MgCaRB is available here and the R/Matlab code is available here and here
The deglacial Southern Hemisphere westerly reconstructions from Gray et al 2023 are available here and here. An online seminar presenting this work is available here.
Please see the publications section below for links to the data/code associated with each paper (code is typically available on my GitHub page).
Short Bio
I use the elemental and isotopic geochemistry of foraminifera to reconstruct climate and carbon cycling, with an emphasis on the Quaternary. Much of my research has focussed on calibrating geochemical proxies in foraminifera, as well as trying to understand their complexities and how we might account for them in the fossil record. My work also looks at how geochemical signals are incorporated during biomineralization, as well as determining the role of calcifying organisms in the alkalinity cycle. I am particularly interested in pairing proxy data and climate model output to understand climate and carbon cycle dynamics.
Publications
data/code links are given where available
Cetiner, J.E.P, Berelsom, W., Rollins, N., Liu, X., Pavia, F.J., Waldeck, A.R., Gray, W.R., Dong, S., Barnhart, H.A., Quinan, M., Wani, R.P., Rafter, P.A., Jacobson, A.D., Byrne, B.H., Adkins, J.F. (2025) Carbonate dissolution fluxes in deep-sea sediments as determined from in situ porewater profiles in a transect across the saturation horizon. Geochimica et Cosmochimica Acta 390, 145-149, https://doi.org/10.1016/j.gca.2024.11.027. Data: https://demo.bco-dmo.org/dataset/925487, https://demo.bco-dmo.org/dataset/925132, https://demo.bco-dmo.org/dataset/925367, https://demo.bco-dmo.org/dataset/925313.
Boscolo-Galazzo, F., Evans, D., Mawbey, E. M., Gray, W. R., Pearson, P. N., Wade, B. S. (2025) Exploring macroevolutionary links in multi-species planktonic foraminiferal Mg/Ca and δ18O from 15 Ma to recent. Biogeosciences, 22, 1095–1113, https://doi.org/10.5194/bg-22-1095-2025. Data/Code: https://doi.org/10.5281/zenodo.14847243, https://doi.org/10.5281/zenodo.14056982
Dong, S., Pavia, F., Subhas, A., Gray, W.R., Berelson, W., Adkins, J. (2025) Carbon Cycling in Marine Particles Based on Inorganic and Organic Stable Isotopes. Geochimica et Cosmochimica Acta. https://doi.org/10.1016/j.gca.2024.10.005
Alves, A. Buisson, M., Louvat, P., Rollion-Bard, C., Bassinot, F., Gray, W.R., Paris, G., Caron, B., Del Manzo, G., Le Friant, A., Moreno, E., Bartolini, A. (2024) Sea surface acidification events in the Andaman Sea associated with the last Toba volcanic activity. Global Planetary Change, 237, 104460, https://doi.org/10.1016/j.gloplacha.2024.104460
Millet, B*., Gray, W.R., de Lavergne, C., Roche, D. (2024) Oxygen isotope constraints on the ventilation of the modern and glacial Pacific. Climate Dynamics. https://doi.org/10.1007/s00382-023-06910-8 *supervised PhD student
Daeron, M & Gray, W.R. (2023) Revisiting oxygen-18 and clumped isotopes in planktic and benthic foraminifera (2023) Paleoceanography and Paleoclimatology. doi: 10.1029/2023PA004660. Data/Code: https://github.com/mdaeron/isoForam.
Gray, W.R., de Lavergne, C., Jnglin Wills, R.C., Menviel, L., Spences, P., Holzer, M., Kageyama, M., Michel, E. (2023) Poleward shift in the Southern Hemisphere westerly winds synchronous with the deglacial rise in CO2. Paleoceanography and Paleoclimatology, 38, e2023PA004666. https://doi.org/10.1029/2023PA004666. Data: https://doi.org/10.1594/PANGAEA.932846. Code: https://doi.org/10.5281/zenodo.7866501. Note the wind / SST front/ northward Ekman transport reconstructions are given in the supplementary tables accompanying the online version of the manuscript.
Nambiar R., Hauzer H., Gray W.R., W. Henehan M.J., Cotton L., Erez J., Rosenthal., Y., Renema, W., Müller W., Evans, D. (2023) Evaluating the utility of K/Ca in marine carbonates as a recorder of seawater chemistry. Geochimica et Cosmochimica Acta, 351, 125–138. https://doi.org/10.1016/j.gca.2023.04.020
Gray, W.R., Evans, D., Henehan, M., Weldeab, S., Lea, D.W., Muller, W., Rosenthal, Y. (2023) Sodium incorporation in foraminiferal calcite: an evaluation of the Na/Ca salinity proxy and evidence for multiple Na-bearing phases. Geochimica et Cosmochimica Acta, 384, 152-164. https://doi.org/10.1016/j.gca.2023.03.011. Data: https://doi.pangaea.de/10.1594/PANGAEA.961099.
Ziveri, P., Gray, W.R.*, et al. (2023) Calcium carbonate production and shallow dissolution in the pelagic North Pacific Ocean, Nature communications, 14, 805. https://doi.org/10.1038/s41467-023-36177-w *joint first author. Data: https://doi.org/10.1594/PANGAEA.948508. Code: https://doi.org/10.5281/zenodo.7458132.
Rafter, P., Gray, W.R, Hines, S.K.V., Burke, A., Costa, K.M., Gottschalk, J., Hain, M.P., Rae, J.W.B, Southon, J.R., Walczack, M.H., Yu, J., Adkins, J.F., DeVries, T. (2022) Global reorganization of deep-sea circulation and carbon storage after the last ice age. Science Advances, 8, 46. doi: 10.1126/sciadv.abq5434. Data: https://doi.pangaea.de/10.1594/PANGAEA.946522.
Peral, M. Y., Bassinot, F., Daeron, M., Blamart, D., Bonnin, J., Jorissen, F., Kissel, C., Michel, E., Waelbroeck, C., Rebaubier, H., Gray, W.R. (2022) On the combination of the planktonic foraminiferal Mg/Ca, clumped (Δ47) and conventional (δ18O) stable isotope paleothermometers in palaeoceanographic studies. Geochimica et Cosmochimica Acta, 339, 22-34. https://doi.org/10.1016/j.gca.2022.10.030.
Judd, E.J., Tierney, J.E., Huber, B.T. et al. The PhanSST global database of Phanerozoic sea surface temperature proxy data (2022) Sci Data 9, 753 https://doi.org/10.1038/s41597-022-01826-0. Data: https://zenodo.org/records/7275402.
Subhas, A. V., Dong, S., Naviaux, J. D., Rollins, N. E., Ziveri, P., Gray, W., et al. (2022) Shallow calcium carbonate cycling in the North Pacific Ocean. Global Biogeochemical Cycles, 36, e2022GB007388. https://doi. org/10.1029/2022GB007388. Data: https://www.bco-dmo.org/dataset/856409 / https://www.bco-dmo.org/dataset/860424 / https://www.bco-dmo.org/dataset/860409 / https://www.bco-dmo.org/dataset/836954
Weldeab, S., Rühlemann, C., Ding, Q., Khon, V., Schneider, B., Gray, W.R. (2022) Impact of Indian Ocean surface temperature gradient reversals on the Indian Summer Monsoon. Earth and Planetary Science Letters 578, 117327. https://doi.org/10.1016/j.epsl.2021.117327. Data: https://doi.pangaea.de/10.1594/PANGAEA.942059
Stewart, J.A., et al. (2021) NIST RM 8301 Boron Isotopes in Marine Carbonate (Simulated Coral and Foraminifera Solutions): Inter-laboratory d11B and Trace Element Ratio Value Assignment. Geostandards and Geoanalytical Research, https://doi.org/10.1111/ggr.12363
Gray, W. R., Wills, R. C. J., Rae, J. W. B., Burke, A., Ivanovic, R. F., Roberts, W. H. G., et al. (2020) Wind-driven evolution of the North Pacific subpolar gyre over the last deglaciation. Geophysical Research Letters 47, e2019GL086328. https://doi.org/ 10.1029/2019GL086328. Data: https://doi.pangaea.de/10.1594/PANGAEA.912229. Code: https://github.com/willyrgray/npac_gyres.
Rae, J.W.B., Gray, W.R., Wills, R., Eisman, I., Fitzhugh, B., Fotheringham, M., et al. (2020) Overturning circulation, nutrient limitation, and warming in the Glacial North Pacific. Science Advances 6, eabd1654. DOI: 10.1126/sciadv.abd1654.
Evans, D., Gray, W. R., Rae, J. W. B., Greenop, R., Webb P. B., Penkman, K., Kroger, R., Allison, N (2020) Trace and major element incorporation into amorphous calcium carbonate (ACC) precipitate from seawater. Geochimica et Cosmochimica Acta 290, 293-311, https://doi.org/10.1016/j.gca.2020.08.034.
Tierney, J.E., Malevich, S.B., Gray, W.R., Vetter, L., Thirumalai, K. (2019) Bayesian calibration of the Mg/Ca paleothermometer in planktic foraminifera. Paleoceanography and Paleoclimatology, 10.1029/2019PA003744. Data: https://doi.pangaea.de/10.1594/PANGAEA.908097. Code: https://github.com/jesstierney/BAYMAG.
Shao, J., Stott, L. D., Gray, W. R., Greenop, R., Pecher, I., Neil, H. L., et al. (2019). Atmosphere?ocean CO2 exchange across the last deglaciation from the Boron Isotope Proxy. Paleoceanography and Paleoclimatology, 34. https://doi.org/ 10.1029/2018PA003498
Khider, D., Emile, Geay, J., McKay, N. P., Gil, Y., Garijo, D., Ratnakar, V., et al. (2019). PaCTS 1.0: A crowdsourced reporting standard for paleoclimate data. Paleoceanography and Paleoclimatology, 34. https://doi. org/10.1029/2019PA003632
*Gray W.R. & Evans, D. (2019) Nonthermal influences on Mg/Ca in planktonic foraminifera: A review of culture studies and application to the last glacial maximum. Paleoceanography and Paleoclimatology 34. https://doi.org/ 10.1029/2018PA003517. *Invited review. Code: https://github.com/willyrgray/MgCaRB. ***A web app version of MgCaRB is available here***
Gray W.R., Rae, J.W.B, Wills, R.C.J., Shevenell, A.E., Taylor, B., Burke, A., Foster, G.L., Lear, C.H. (2018) Deglacial upwelling, productivity and CO2 outgassing in the North Pacific Ocean. Nature Geoscience 11, 340-344. See also ‘Nature Geoscience News and Views’, doi:10.1038/s41561-018-0119-3. Data: https://doi.org/10.1594/PANGAEA.887381.
Gray, W.R., Weldeab, S., Lea, D.W., Rosenthal, Y., Gruber, N., Donner, B., Fisher, G. (2018) The effects of temperature, salinity, and the carbonate system on Mg/Ca in Globigerinoides ruber: A global sediment trap calibration. Earth and Planetary Science Letters 482, 607-620, https://doi.org/10.1016/j.epsl.2017.11.026. Data: https://doi.org/10.1594/PANGAEA.885877
Taylor, B., Rae, J., Gray., W.R., Darling, K., Burke, A., Gersonde, R., Abelmann, Maier, E., Esper, O., Ziveri, P. (2018) Distribution and ecology of planktic foraminifera in the North Pacific: Implications for paleo-reconstructions. Quaternary Science Reviews 191, 256-274. https://doi.org/10.1016/j.quascirev.2018.05.006
Drury, A. J., Lee, G. P., Gray, W. R., Lyle, M., Westerhold, T., Shevenell, A. E., John C. M. (2018) Deciphering the state of the late Miocene to early Pliocene equatorial Pacific. Paleoceanography 33, 246-263. https://doi.org/10.1002/2017PA003245
Frings, P., Clymans, W., Fontorbe, G., Gray, W.R., Chakrapani, G., Conley, D., De La Rocha, C. (2015) Silicate weathering in the Ganges alluvial plain. Earth and Planetary Science Letters 427, 136-148. https://doi.org/10.1016/j.epsl.2015.06.049
Gray, W.R., Holmes, J.A. and A.E. Shevenell (2014) Evaluation of foraminiferal trace element cleaning procedures on the Mg/Ca of marine ostracod genus Krithe. Chemical Geology 382, 14-23. https://doi.org/10.1016/j.chemgeo.2014.05.022
Frings, P., Conley, D., Struyf, E., van Pelt, D., Schoelynck, J., Murray Hudson, M., Gondwe, M., Wolski, P., Mosimane, K., De La Rocha, C., Gray, W.R., Schaller, J. (2014) Tracing silicon cycling in the Okavango Delta, a sub-tropical flood-pulse wetland. Geochimica et Cosmochmica Acta 142, 132-148.
Assorted
Mg/Ca paleothermometry
Mg/Ca derived SST (colours) with measured SST (grey) at the Sargasso Sea sediment trap/BATS. The calibrations of Gray et al 2018/ Gray and Evans 2019 do a reasonable job of capturing both the absolute and seasonal variation in measured SST at this site. The calibration of Anand et al. 2003 does not (despite the fact this is the site used in that calibration).
A web app version of MgCaRB (a tool to covert Mg/Ca to SST accounting for pH and salinity) is available here and the R/Matlab code is available here and here
The data from our 2018 global sediment trap study is available here.
Boron isotopes and the carbon cycle
Boron isotopes in foraminifera track seawater pH, giving us a powerful tool to reconstuct past CO2 concentrations and track the carbon cycle.
Stack of surface ocean pH and pCO2 from boron isotopes showing deglacial CO2 outgassing
(Shao et al,. 2019)
Using spatial patterns of δ18O to reconstruct past climate dynamics
We can use basin-scale compilations of planktic foraminiferal δ18O and climate models to look changes in atmospheric and surface ocean circulation over deglaciation.
Tracking the latitudinal movement of the gyre boundary in the North Pacific over deglaciation using the spatial pattern of δ18O
Reconstruction of shifts in the southern hemisphere westerly winds over the last deglaciation using changes in the spatial pattern of δ18O and ’emergent relationships’ in an ensemble of climate models (Gray et al 2023)
pelagic calcifiers in the modern ocean and the alkalinity cycle
Carbonate production by pelagic calcifiers removes alkalinity from the surface ocean and exports it to the deep ocean, however estimates of how much calcium carbonate is produced, who makes it (forams/coccos/pteropods), and how much of it makes it into the deep ocean/sediments vary wildly. Our work shows while most of this CaCO3 is produced by coccolithophores, much of this CaCO3 dissolves in the upper ocean due to biologically mediated dissolution.
Pteropods produce aragonite. Collected on the C-DisK-IV cruise.