Two-million-year record of fire in temperate East Asia

Fire is one of the most active agents in shaping terrestrial ecosystems and it has played a significant role in the complex interactions between climate, vegetation, and hominins. Here, we present records of microcharcoal and stable carbon isotopes from a two-million-year long sedimentary sequence from temperate East Asia and use it to reconstruct the long-term fire history. Our results indicate that fire frequency over the last two million years fluctuated substantially and had an inverse relationship with the abundance of C4 plants. The fire frequency during 2.1–0.3 Ma was relatively low, but after 0.3 Ma, the colder and drier climate likely resulted in much frequent fires and anthropogenic impacts probably also affected fire regime. Additionally, the charcoal time series is correlated with variations in Earth orbital parameters, suggesting the influence of orbitally-driven insolation variations on fire. During glacial periods, the dry climate contributed to increased fire activity due to the overall increase in fuel availability. A comparison of our results with global fire records confirms that insolation variations modulated by Earth orbital cycles played a key role in driving fire activity during the Quaternary.