OPP-PRF: Assessing the relationship among fire, temperature, and precipitation in the Arctic during the Pleistocene

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Rising temperatures associated with increasing atmospheric carbon dioxide (CO2) concentrations are causing more fire events globally, including in the Arctic. Arctic fire events have regional impacts including changing the plant community to those that are more flammable. In addition, the burning of previously frozen Arctic soils can release stored carbon, adding more CO2 to the atmosphere. The intensity and number of wildfires in a region are controlled mainly by temperature and precipitation. Climate models can project future temperature well but regional precipitation data are limited which hampers the ability to accurately project Arctic wildfires. This study will compare wildfire frequency to temperature and precipitation during times in the past that were not influenced by human activity. The results can be used to improve regional Arctic climate models of precipitation impact on fire frequency. Results of this study will be communicated to policymakers to assist with decision making in response to future warming. The project will generate educational materials and hands-on science projects related to climate change and fire in the Arctic for outreach to primary school students around the country through virtual classrooms. The project will engage undergraduates through lab work, a conference presentation, and a workshop for the Eureka! Summer Science Camp at the University of Massachusetts which engages girls ages 12-18 to explore STEM fields. Fire disturbances are predicted to increase in the Arctic with rising temperatures while precipitation also impacts fire frequency and intensity. Future projections show increases in temperature, precipitation, and fire events. However, climate models are limited in their ability to reconstruct precipitation, which inhibits estimates of fire frequency. In addition, it is unclear if precipitation is the primary driver of fire frequency or if it works in tandem with rising temperatures. Previous assessments of past Arctic fires have produced contrasting results with both wetter and more arid conditions being associated with an increase in fire. To address this, more precipitation records that exclude the impact of human-induced fires are needed to constrain potential feedbacks. This research will investigate variability in Arctic climate through reconstructing precipitation, temperature, and fire throughout the Pleistocene using organic geochemical techniques. Ocean Drilling Program Site 647, located near southern Greenland, will be studied as this Site spans known interglacials such as Marine Isotope Stage (MIS) 11 and super interglacial MIS 31-33. Sea surface temperatures (SST) generated from three different organic geochemical techniques will be compared to concentrations of compounds produced by burning biomass, such as polycyclic aromatic hydrocarbons (PAHs) and levoglucosan. These data will allow examination of time periods of increasing wildfires in connection with the temperature history. The SST and fire biomarker concentration will be compared to hydrogen isotopes (δ2H) of plant leaf waxes from the same core, which provides additional information on moisture transport pathways in the Arctic. The study will evaluate if higher temperatures during interglacials result in more poleward moisture transport, which is reflected in more enriched δ2H due to changes in moisture source as increasing temperatures leads to wetter conditions in the Arctic. Overall, the use of multiple proxies will generate new records spanning both glacial and interglacial periods across the Pleistocene to assess variability in the relationships between temperature, precipitation, moisture source, and fire in the Arctic.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.