Holocene wildfire on the Qinghai-Tibetan Plateau–witness of abrupt millennial timescale climate events

Abstract

As the latest interglacial, the Holocene is an ideal period to determine wildfire activity during abrupt climate events, which can help elucidate the connection between wildfire occurrence (especially extreme wildfires) and climate change. In this study, we reconstruct a Holocene wildfire history using soot record from Qinghai Lake sediments in the northeast margin of the Tibetan Plateau. This record reflects climate change on a regional scale. Except for enhanced wildfire activity during the middle-late Holocene when climate became dry, the results also show rapid increasing periods of wildfire centered at ca. 1.6, 2.5, 4.1, 4.9, 6.3, 7.8, 9.6, 10.5 and 11.4 calibrated kiloyears before present (cal ka BP) that are strongly correlated with abrupt climate events. Drought climate in association with a weakened monsoon appear to be the major factor driving the increase of wildfires on sub-orbital and millennial timescales, likely modulated by solar radiation (activity). Potential human activities may promote wildfire occurrences and enhance soot emissions to some extent as well. The connection of wildfire with millennial timescale abrupt dry/cold climate events may differ from the broad expectation of increased fire occurrences in warmer periods and can provide new insights for fire prediction.