Miocene fire intensification linked to continuous aridification on the Tibetan Plateau

International audience; Although fire is considered an importantfactor in global vegetation evolution and cli- mate change, few high-resolution Miocene fire records have been obtained worldwide. Here, two independent micro-charcoal–based fire records from the northern Tibetan Plateau were analyzed; both show similar trends in micro- charcoal concentrations through time, with low abundances in the warmer Middle Miocene Climate Optimum (18–14 Ma) followed by a continuous increase throughout the late Mio- cene (14–5 Ma) cooling. Our detailed statistical analyses show that the micro-charcoal concen- tration trend is highly positively correlated to the trend in oxygen isotopes (δ18O, r = 0.94) and xerophytic species (%Xero, r = 0.95). We propose that the intensified fire frequency on the Tibetan Plateau mainly originated from the forest-steppe ecotone as a result of the continuous aridifica- tion in winter driven by the global cooling and decreased atmospheric pCO2 that occurred dur- ing 18–5 Ma, with a secondary control by the tectonic activity of the northern Tibetan Plateau.