Research Projects

The Plio-Pleistocene transition (PPT) marked an abrupt climate shift from warm-humid to cold-arid due to a significant decline in atmospheric pCO2 resulting from excessive production of terrestrial organic carbon (OC) triggering enhanced erosion, transport and subsequent OC locking during burial process. Recent researches hypothesized an enhanced wildfire activity globally during this transition. However, the record of this increased wildfire activity remains understudied from Indian geological archives. A sole marine record has been investigated till date which creates a major gap in scientific knowledge, since the marine record is based on the terrigenous clay-bound nitrogen isotope (δ15NNH4+) proxy assuming transportation and burial processes did not alter the isotopic fractionation. Therefore, a study of good continental archive will lessen the probability of isotopic fractionation that occurs during long transportation and residence time in seawater. Furthermore, the record of PPT wildfires across globe is scarce, especially molecular biomarker evidences. Combustion derived polycyclic aromatic hydrocarbon (PAH) biomarkers are excellent indicators of wildfire activity which have not been utilized to study the PPT wildfires from the Indian archives, marine or continental. Moreover, the colder climate of Pleistocene (~5°C colder than today at peak glaciation) discords the common concept of elevated atmospheric temperature promoting wildfires. A detailed study is thus required to answer how this colder climate triggered wildfires globally and the impacts on the biotic community. The continental record of PPT is preserved in NW Himalayan Siwalik section. The present proposal envisages an extensive study including geochemical (TOC, TC, TN, δ13Corg, δ15Nbulk and δ15NNH4+) and biomarker analyses (lipids, terpenoids, PAHs etc.) through Rock-Eval pyrolysis, EA–IRMS, GC–MS to – a) Establish the climatic history and trace the wildfire activities during PPT from continental sedimentary records b) Determine whether the climatic shift or some external factors elicited the wildfires c) Elucidate the biotic response due to the climate shift and wildfire activities The current proposal envisages a multi-proxy investigation of continental archives to decipher the cause of heightened wildfire activities during PPT and impact on global carbon sink as well as the fate of biotic community. The project will bridge the gap in knowledge regarding PPT wildfires from a continental perspective and generate research publications in peer-reviewed journals which will provide the basis for future researches on paleo wildfires due to climatic events. In the last two decades, the frequency and magnitude of fires have almost doubled which has been linked to climate, ~38.1 kha of tree cover loss in India. With increasing global warming, the study of paleo fires will provide understanding of the factors modulating the fires and serve as an analogue for future occurrences.