Paleofire activity reconstruction in the Tibetan Plateau

Abstract

Biomass burning as a natural process producing greenhouse gases may influence both regional and global climate, and it has become of planetary concern due to anthropogenic activities (Simoneit, 2000; Hopmans et al., 2012; Zennaro et al., 2014). The present work gives information about past fire events in the Tibetan Plateau and helps to increase the understanding of the interaction between Holocene's climate and fire activity. Tibetan Plateau is located in Asia, which is known to be the Earth's largest and most populated continent, and its extension is approximately 1,000 km north to south and 2,500 km east to west, with an average elevation exceeding 4,500 m. We reconstructed biomass burning events of the last 10,500 years recorded in sediments collected from lake Paru Co (4,845 m above sea level), a small moraine dammed lake located on the South-Eastern Tibetan Plateau. Sediment samples were extracted using accelerate solvent extraction and different organic molecular proxies were analysed by GC-MS and IC-MS. We used monosaccharide anhydrides, levoglucosan and its isomers and polycyclic aromatic hydrocarbons as proxies for biomass burning. These are specific molecular markers originated from the pyrolysis of cellulose showing significant fire events and indicate changes in burned fuel. The relationship between this multi-proxy approach and climatic, meteorological and charcoal data allows the reconstruction and contextualization of past fire events and suggests a correspondence between dry climate period and presence of more intense fire events, especially in the Early Holocene.