Climatic history of the northeastern United States during the past 3000 years

Marlon J.R. et al. (2017) Climatic history of the northeastern United States during the past 3000 years. Environmental Data Initiative, http://dx.doi.org/10.6073/pasta/6ced33c5e07f9fa7f11efb259001bacb.

Many ecosystem processes that influence Earth system feedbacks – vegetation growth, water and nutrient cycling, disturbance regimes – are strongly influenced by multidecadal- to millennial-scale climate variations that cannot be directly observed. Paleoclimate records provide information about these variations, forming the basis of our understanding and modeling of them. Fossil pollen records are abundant in the NE US, but cannot simultaneously provide information about paleoclimate and past vegetation in a modeling context because this leads to circular logic. If pollen data are used to constrain past vegetation changes, then the remaining paleoclimate archives in the northeastern US (NE US) are quite limited. Nonetheless, a growing number of diverse reconstructions have been developed but have not yet been examined together. Here we conduct a systematic review, assessment, and comparison of paleotemperature and paleohydrological proxies from the NE US for the last 3000 years. Regional temperature reconstructions (primarily summer) show a long-term cooling trend (1000 BCE–1700 CE) consistent with hemispheric-scale reconstructions, while hydroclimate data show gradually wetter conditions through the present day. Multiple proxies suggest that a prolonged, widespread drought occurred between 550 and 750 CE. Dry conditions are also evident during the Medieval Climate Anomaly, which was warmer and drier than during the Little Ice Age and drier than today. There is some evidence for an acceleration of the longer-term wetting trend in the NE US during the past century; coupled with an abrupt shift from decreasing to increasing temperatures in the past century, these changes could have wide-ranging implications for species distributions, ecosystem dynamics, and extreme weather events. More work is needed to gather paleoclimate data in the NE US to make inter-proxy comparisons and to improve estimates of uncertainty in reconstructions.

Most recent analysis paper derived from this dataset: Marlon JR, N. Pederson, C. Nolan, S. Goring, B. Shuman, A. Robertson, R. Booth, P.J. Bartlein, M.A. Berke, M. Clifford, E. Cook, A. Dieffenbacher-Krall, M.C. Dietze, A. Hessl, J. Hubeny, S.T. Jackson, J. Marsicek, J. McLachlan, C.J. Mock, D.J.P. Moore, J. Nichols, D. Peteet, K. Schaefer, V. Trouet, C. Umbanhowar, J.W. Williams and  Z. Yu. (2017) Climatic history of the northeastern United States during the past 3000 years. Climate of the Past, 13, 1355–1379, https://doi.org/10.5194/cp-13-1355-2017.

cp-2016-104-f07-web
(From Marlon JR et al. 2017, https://doi.org/10.5194/cp-13-1355-2017) Hydroclimatic reconstructions for the last 3000 years for the NE US and adjacent regions from diverse paleoclimatic proxies and archives. A) Tree-ring based reconstructions of PDSI; B) Composite index of two varve thickness records from Green Lake, New York, and the Pettaquamscutt River Estuary, Rhode Island ; C) Drought events (marked with “+”) and event summary based on water table reconstructions from testate amoeba in western kettle-hole peatlands (Pinhook and South Rhody), western bogs (Irwin Smith and Minden), and eastern bogs (Sidney, Saco, and Great Heath); D) Bog record counts; E) ratio of Sphagnum to vascular plants from the Great Heath bog, Maine ; F) drought indicator based on Isothermal Remanent Magnetization at White Lake, New Jersey; G) lake level reconstructions from Deep, Davis, and New Long ponds in Massachusetts, and lake-level change estimates from Matthews Pond and Whitehead Lake, Maine; and H) Precipitation and P-E rate anomalies from the TraCE-21k simulations. Vertical gray bands are provided as a visual aid to identify the timing of features in the records. Pink and blue vertical bars mark the MCA and LIA intervals. For citations  referenced in this figure, please see Fig.7 in Marlon JR et al. 2017, https://doi.org/10.5194/cp-13-1355-2017.

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