Climate Factors Leading to Asymmetric Extreme Capture in the Tree-Ring Record

Abstract

Paleoclimate data play a critical role in contextualizing recent hydroclimate extremes, but asymmetries in tree-ring responses to extreme climate conditions pose challenges for reconstruction and interpretation of past climate. Here we establish the extent to which existing tree-ring records capture precipitation extremes in western North America and evaluate climate factors hypothesized to lead to asymmetric extreme capture, including timing of precipitation, seasonal temperatures, snowpack, and atmospheric river events. We find that while there is dry-biased asymmetry in one third of western North American tree-ring records, 45% of sites capture wet extremes as well as or better than dry extremes. Summer extremes are rarely captured at any sites. Latitude and elevation affect site-level extreme responses, as do seasonal climate conditions, particularly in the autumn and spring. Directly addressing asymmetric extreme value capture in tree-ring records can aid our interpretation of past climate and help identify alternative avenues for future reconstructions.