Reconstructing Late Holocene Climate and Coastal Evolution for the Northeastern United States

Abstract

Paleoclimate data provide the opportunity to understand the Earth's climate system on timescales from decades to millennia, as well as quantify the frequency and magnitude of global change. This information cannot be concretely determined from relatively short instrumental observations alone. Long, annually resolved climate and paleoclimate records help evaluate the impacts of global change and characterize internal variability of the Earth system. Paleoclimate reconstructions in the northeastern United States have pervasive uncertainties due to the deficiency of high-resolution temperature-sensitive proxy records in the region. Tree-ring chronologies in the Northeast, in particular, typically exhibit mixed moisture and temperature sensitivity, convoluting the climate signal for reconstructions. Here, I develop an extensive network of precisely dated and annually-resolved late Holocene tree-ring chronologies from living and preserved (subfossil) forests of Chamaecyparis thyoides (Atlantic White cedar, `AWC'), throughout the northeastern United States. I demonstrate the utility of AWC as a novel, high-precision, paleotemperature and coastal paleohydroclimate proxy. The data presented in this dissertation are used to generate the first spatial temperature reconstruction for the Northeast and provide crucial information about extreme hydrologic events affecting the heavily populated Boston to New York metropolitan coastal corridor. The coastal location of the AWC network provides a unique opportunity for multiproxy studies of both low-frequency coastal climate trends and punctuated events, including large storms, along the New England coastline. I use a combination of subfossil wood, radiocarbon, and sediment cores of near-shore environments to develop precisely dated tree-ring chronologies that reach back beyond the Common Era and examine the impacts of hurricanes on coastal ecosystems. These paleoclimate data fill a critical data gap, are used to improve and extend the climate history of New England, and identify the occurrence, frequency, of broad-scale climate phenomena and the impacts of extreme events.