Reconstructions of Arctic climate seasonality during the Cenozoic using fossil wood

Determination of seasonal climate conditions represents a critical advance beyond the reconstruction of mean annual climate, particularly in Arctic environments. Workers have long used natural abundance stable isotope ratios (δ13C and δ18O) measured in tree rings to interpret annual climate trends and variability across multiple consecutive years. More recently, however, researchers have improved upon single-ring measurements by developing a variety of methods for subsampling across single tree-rings, including hand slicing, microtome sectioning, and laser ablation. This work has revealed large-scale changes in δ13C and δ18O value within each growth ring that relate to changes in seasonal precipitation and temperature. Here I will present high-resolution δ13C and δ18O data on fossil wood collected from across the Arctic in order to reconstruct summer and winter precipitation and temperature. Results from this work highlight the importance of sea ice cover on Arctic climate throughout the Cenozoic, and suggest that changes in seasonal precipitation and temperature carry significant implications for ecosystem productivity and carbon storage within Arctic regions.