Geochemical Evidence for Biomass Burning Signals on Tibetan Glaciers

Abstract

Geochemical components in Tibetan glacier snow and ice can provide fingerprints of biomass burning (BB). This work summarized our current understandings on BB signals on Tibetan glaciers, especially for focusing on levoglucosan (LEV) and black carbon (BC). The BB sources and prevailing atmospheric circulations controlled the overall spatial distribution of BB signals on Tibetan glaciers. Although BB signals were detected even in central Tibetan glaciers, results supported the idea that Tibetan glaciers were as clean as representative of regional backgrounds. The post-depositional melting and refreezing processes in the accumulation area reshaped the temporal distribution patterns of LEV and BC at some extent. LEV in glacier accumulation area can be used as a proxy for representing the primary characteristics of BB changes at least on seasonal-to-annual timescales. Continuous LEV records in ice layers can capture the signals of discrete fire events as well as the long-term trend, and thus can be used as a powerful tool for calibrating past BB changes. A rapid increase in wildfires at the beginning of the 21st century was reconstructed in a central Tibetan ice core records, and climate change was the dominant factor.