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.
Follow me on twitter @willerstorfi.
A complete publication list is available on Google Scholar.
My work looks at calibrating Mg/Ca in planktic foraminifera, assessing the non-thermal influences, and understanding how we can use Mg/Ca as an accurate paleothermometer. I am also interested in using trace elements to understand how foraminifera biomineralise, and as proxies for the carbonate-system.
Gray, W. R., Weldeab, S., Lea, D. W., Rosenthal, Y., Gruber, N., Donner, B., & Fischer, G. (2018) The effects of temperature, salinity, and the carbonate system on Mg/Ca in Globigerinoides ruber (white): A global sediment trap calibration. Earth and Planetary Science Letters, 482, 607–620. (paywalled - click here for a free version)
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 (free access)
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, 34. https://doi.org/10.1029/2019PA003744
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.
The data from our 2018 global sediment trap study is available here.
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
Boron isotopes in foraminifera track seawater pH, giving us a powerful tool to reconstuct past CO2 concentrations. I use boron isotopes to understand the oceans role in driving Glacial-Interglacial changes in CO2. I am currently developing the foraminiferal boron isotope method at LSCE.
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, 330-344. (paywalled - click here for a free version)
Shao, J., Stott, L.D., Gray, W.R., Greenop, R., Percher, I., Neil, H.L., Coffin, R.B., Davy, B., Rae, J.W.B. (2019) Atmosphere-Ocean CO2 Exchange Across the Last Deglaciation from the Boron Isotope Proxy. Paleoceanography, https://doi.org/10.1029/2018PA003498.
Stewart. J.A., et al. (2020) NIST RM 8301 Boron isotopes in Marine Carbonates (Simulated Coral and foraminifera Solutions): Inter-laboratory d11B and trace Element Ratio Value Assignment. Geostandards and Geoanalytical research, https://onlinelibrary.wiley.com/doi/full/10.1111/ggr.12363.
Rae, J.W.B., Gray, W.R., Wills, R., Eisman, I., Fitzhugh, B., Fotheringham, M., et al (2020) Overtuning circulation, nutirent limitation, and warming in the Glacial North Pacific. Science Advances 6, eabd1654. DOI: 10.1126/sciadv.abd1654.
I am using basin-scale compilations of planktic foraminiferal δ18O and climate models to look changes in atmospheric and surface ocean circulation over deglaciation. Using these methods we showed a 3° southward shift the subtropical/subpolar gyre boundary and westerly winds in the North Pacific durint the LGM (Gray et al., 2020). I am currently applying these methods to the Southern Ocean, and future plans involve the North Atlantic!
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 wildely; as part of the CDisk-4 cruise, we are trying to figure out how much carbonate is produced by foraminifera, coccolithophores, and pterpods, and how much of this sinks into the deep ocean. New results soon!