The atmospheric physics group has a new paper in Science on soil respiration–driven CO2 pulses above Australia. Eva-Marie Metz, Sanam Vardag, Andre Butz and co-workers found pulses in CO2 concentrations recurring at the end of the dry season above Australia in most years. They evaluated measurements by the Greenhouse Gases Observing Satellite (GOSAT), inferred the compatible CO2 fluxes at the ground and compared those to various model estimates. It turned out that a few of the models capture the pulses suggesting that they originate from a quick response of microbial respiration at the onset of rain after the dormant period. While this effect has been observed in the context of the "Birch effect" locally, it remained unknown that it dominates the seasonal CO2 dynamics of the entire Australian continent.
Metz, E.-M., Vardag, S. N., Basu, S., Jung, M., Ahrens, B., El-Madany, T., Sitch, S., Arora, V. K., Briggs, P. R., Friedlingstein, P., Goll, D. S., Jain, A. K., Kato, E., Lombardozzi, D., Nabel, J. E. M. S., Poulter, B., Séférian, R., Tian, H., Wiltshire, A., Yuan, W., Yue, X., Zaehle, S., Deutscher, N. M., Griffith, D. W. T., and Butz, A.: Soil respiration-driven CO2 pulses dominate Australia’s flux variability, Science, 379, 1332–1335, https://www.science.org/doi/abs/10.1126/science.add7833, 2023.