Wildfire Activity in the Denali Ice Core

Wildfires are becoming more destructive as the climate changes. Understanding how fire regimes will respond as the climate continues to change is critical to fire management practices. Paleofire records provide insight into how fire regimes have responded to climate change in the past. Ice cores capture fire proxies such as black carbon at an annual resolution on a regional scale. This makes them ideally suited to construct high temporal resolution, regional paleofire records. Before we can construct paleofire records from an ice core, we must learn how to interpret the proxy data. Here we show how to evaluate instrumental fire activity data which will provide the ground truth to which we can calibrate the fire proxies. Using the Denali ice core, we show how to determine the atmospheric catchment to constrain the region of study. We then use observational fire datasets, covering the region captured by the core, to determine relationships between metrics such as the number of fires and area burned in a given year; in the Denali core, these metrics are strongly correlated and can be used nearly interchangeably. Both fire activity and the ice core are impacted by climate variables, so we show how factors such as precipitation and temperature impact individual fires, as well as seasonal fire activity. Building a paleofire record from the Denali ice core will enable the study of both the Alaska fire regime and the summer climate changes in Alaska that drive changes in fire. This paleofire record will allow for a better understanding of how Alaskan wildfire is expected to change in the near future.