- 1Indian Institute of Science, Divecha Centre for Climate Change, India (thamizharasa@iisc.ac.in)
- 2Indian Institute of Science, Centre for Earth Sciences, India
- 3Jamia Millia Islamia, Department of Environmental Science, India
- 4Birbal Sahni Institute of Palaeosciences, India
The Plio-Pleistocene transition (1.5–3 million years ago) was marked by a significant drop in the atmospheric CO2 level by approximately 140 ppm, driving global cooling and amplifying glacial-interglacial cycles [1,2]. While glaciation-induced continental erosion and terrestrially derived organic carbon (OC) burial are typical factors considered key drivers, these processes do not fully explain the causal mechanism in driving the CO2 drawdown without including regions near mid- and low-latitudes [3]. The ecosystem responses to wildfires and post-fire storms can help elucidate these changes. Here, we investigate the impact of wildfires on OC burial rates at regional and global scales from 4 to 1.5 Ma. Regionally, we reconstructed wildfire activity across South Asia using stable nitrogen isotopes of fixed ammonium in clay minerals and pyrogenic carbon abundances. Our study focused on sedimentary records from the Kashmir Siwalik sedimentary succession and the Nicobar Fan sediments from IODP Expedition 362, Site U1480, which provide insights into processes associated with the Andaman-Nicobar accretionary prism and the Indo-Myanmar ranges. The findings reveal a significant intensification of wildfire activity during the Plio-Pleistocene transition (1.5–3.0 Ma), accompanied by a 2.9- and 2.4-fold increase in continental erosion rates and organic carbon burial flux compared to the early Pliocene (3.0–4.0 Ma). We compiled a comprehensive wildfire dataset on a global scale, integrating 20 proxy records from continental and marine sediments. By combining sediment OC content and Mass Accumulation Rate data from 23 ODP/IODP sites worldwide, we quantified the global rate of OC burial. Our findings reveal a dramatic 4.8-fold increase in wildfire activity and a 1.5-fold rise in global OC burial rates, from 2.29 ± 0.48 Mt C per year during the early Pliocene to 3.52 ± 0.80 Mt C per year at the Plio-Pleistocene transition. These results highlight the significant role of fire-driven processes in atmospheric CO2 drawdown, a mechanism that previous studies have largely overlooked.
References:
[1] Hönisch et al., 2023. Science, 382(6675), p.eadi5177.
[2] Hansen et al., 2013. Philos. Trans. R. Soc. A Math. Phys. Eng. Sci. 371(2001), p.20120294.
[3] Herman et al., 2013. Nature, 504(7480), pp.423-426.
How to cite: Sakthivel, T., Ghosh, P., Ali, S., and Munazir Chauhan, M.: Plio-Pleistocene CO2 drawdown related to wildfire-induced terrestrial organic carbon burial, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-504, https://doi.org/10.5194/egusphere-egu25-504, 2025.
