Ph.D., University of California, Los Angeles, 2017
B.Sc., Nanjing University, 2012

Terrestrial ecosystem ecology, Plant physiological ecology, Biogeochemistry, Biosphere–Atmosphere interactions, Earth system modeling, remote sensing of ecosystems, global change Ecology, machine learning for Ecology

American Geophysical Union (AGU) Editor’s Citation for Excellence in Refereeing (JGR: Biogeosciences), 2024

North American Carbon Program & U.S. Carbon Cycle Science Program Leadership Award, 2022

Jacob A. Bjerknes Memorial Research Award (dissertation award), Department of Atmospheric and Oceanic Sciences, UCLA, 2017

ECOL 4240 Physiological Ecology (Fall 2026)

I study how ecosystems function, particularly how carbon and water cycle processes respond to climate change and reshape future climate trajectories. My current topics of interest include, but are not limited to:

1. Photosynthesis: How does photosynthesis respond to rising CO₂ concentrations across scales, from the leaf to the globe? How do climatic, edaphic, and biotic factors limit the strength of this response?
2. Respiration and decomposition: How does warming affect respiration and soil carbon, particularly in vulnerable, carbon-rich ecosystems such as peatlands, permafrost regions, and wetlands? What are the consequences for the climate?
3. Atmospheric imprints of biospheric change: How can atmospheric trace-gas and isotope observations be used to track biome- and biosphere-scale responses to climate change?
4. The biosphere in Earth system models: How can biospheric processes be represented at the appropriate level of complexity in Earth system models to improve projections of the carbon cycle and carbon–climate feedbacks?
5. Machine learning for ecology: How can differentiable machine learning be leveraged to better constrain process-based ecosystem models using observations?

Sun, W., Foster, K., Shiga, Y., Merder, J., Randazzo, N., & Michalak, A. (2026). Contrasting land carbon uptake responses to El Niño–Southern Oscillation across North America. Under review in Atmospheric Chemistry and Physics. https://doi.org/10.5194/egusphere-2026-880

Sun, W., Luo, X., Fang, Y., Shiga, Y. P., Zhang, Y., Fisher, J. B., Keenan, T. F., & Michalak, A. M. (2023). Biome-scale temperature sensitivity of ecosystem respiration revealed by atmospheric CO2 observations. Nature Ecology & Evolution, 7(8), 1199–1210. https://doi.org/10.1038/s41559-023-02093-x

Sun, W., Berry, J. A., Yakir, D., & Seibt, U. (2022). Leaf carbonyl sulfide to CO2 relative uptake seen through the lens of stomatal conductance–photosynthesis coupling. New Phytologist, 235(5), 1729–1742. https://doi.org/10.1111/nph.18178

Sun, W., Fang, Y., Luo, X., Shiga, Y. P., Zhang, Y., Andrews, A. E., Thoning, K. W., Fisher, J. B., Keenan, T. F., & Michalak, A. M. (2021). Midwest US croplands determine model divergence in North American carbon fluxes. AGU Advances, 2(2), e2020AV000310. https://doi.org/10.1029/2020AV000310

Kooijmans, L. M. J., Sun, W., Aalto, J., Erkkilä, K.-M., Maseyk, K., Seibt, U., Vesala, T., Mammarella, I., & Chen, H. (2019). Influences of light and humidity on carbonyl sulfide-based estimates of photosynthesis. Proceedings of the National Academy of Sciences, 116(7), 2470–2475. https://doi.org/10.1073/pnas.1807600116