Resolving spatiotemporal variability in the hydroclimate of Midcontinental North America in the Common Era

The climate of the Common Era in North America was punctuated by periods of severe drought, pluvials, and variations in the seasonality of precipitation. Numerous hydroclimate records have been developed from paleo-archives located across the west and northeast of North America; however, the midcontinent is presently lacking records that span the last several millennia and reflect either hydroclimate change on a catchment scale or synoptic-scale processes associated with, for example, shifts in air mass trajectories on decadal to centennial scales. Previous work on midcontinental hydroclimate change has shown the presence of a longitudinal hinge line across which an antiphased pattern of precipitation responses occurs. Here, we present results from the synthesis of a geographically diverse ensemble of both newly developed and pre-existing lake sediment hydroclimate records developed utilizing multiple proxies, including oxygen isotopes in authigenic carbonates and changes in sedimentology that reflect lake level variations. Using a Monte Carlo Principal Component approach that quantitatively accounts for age-model uncertainty and potential changes in sedimentation rates, we isolate the predominant signals in the paleo-record ensemble, revealing geographic trends across the region related to the hypothesized, east-west antiphased pattern of midcontinent precipitation changes on intra- to multi-decadal timescales. The midcontinent region, housing more than 70 million people, is dominated by agricultural lands from which many globally significant crops are produced through direct-precipitation and rain-fed irrigation. Global dependence on regional precipitation trends highlights the importance of improving the understanding of midcontinental hydroclimate variability and dynamics.