1200 Years of North Pacific Wildfire Activity from Three Ice Cores

The North Pacific region (Alaska, the Yukon Territory, and Eastern Siberia) has seen dramatic effects of rapidly warming summertime climate, including increased wildfire activity that has resulted in browning trends and carbon release to the atmosphere. To prepare for continued Arctic warming, it is critical to better understand past variations in wildfire activity and its relationships with climate forcing, particularly during warm periods such as the Medieval Climate Anomaly. Ice cores can provide a high-resolution regional history of past wildfire activity and climate (temperature, storminess, precipitation), complementing watershed-scale records from lake sediment cores. The published Eclipse Ice Core (Yukon Territory, Canada) ammonium record showed that wildfire activity was particularly elevated (and above late 20th century levels) from 1250-1400 C.E. (Yalcin et al., 2006), but it is unclear if the Eclipse record represents wildfire activity across the greater North Pacific region. Here, we combine the Eclipse record with two additional North Pacific ice cores (Mt. Logan, Yukon, Canada; Denali Ice Core, Alaska) and additional ice core chemical proxies (e.g., black carbon) to assess North Pacific wildfire trends and spatial variability over the past 1200 years. Preliminary results indicate that wildfire activity was particularly enhanced during the late 1300s, consistent with the findings of Yalcin et al. (2006) from Eclipse. Ongoing investigations are examining relationships between wildfire activity and summertime temperature, precipitation, and atmospheric circulation proxies from the same suite of ice cores along with other paleoclimate records from tree rings and lake sediments.