A proxy-diverse paleoclimate synthesis in North America during the Common Era

Abstract:

Multiple lines of evidence indicate that large late Holocene temperature variations during the Medieval Climate Anomaly (MCA, 950-1250 CE) and Little Ice Age (LIA, 1450-1850 CE) were associated with changing climate patterns in North America (NA). However, significant questions remain regarding the timing, magnitude, spatial patterns, and mechanisms of MCA and LIA climate variability and its relationship to regional hydroclimate, particularly at multi-decadal and centennial timescales. To address these issues, we are synthesizing temperature and precipitation proxy data from continental North America and adjacent ocean regions. Challenges in this effort include: 1) the range of sensitivities of different proxy types to environmental variables, 2) difficulty in reconstructing accurate temperature and rainfall values from proxy data, and 3) a paucity of records, particularly in the central and northern portions of the continent, with adequate temporal resolution and timespan. Excluding some proxy types and records with multi-decadal or lower resolution significantly reduces spatial coverage. Our approach involves a broad selection of lithological, geochemical, and biological proxies from a wide range of environments, including several types of terrestrial sedimentary depositional settings, coastal marine sediments, ice cores, and speleothems, in an effort to capture the full range of temperature and hydroclimate variations.

In this presentation, we present preliminary results from over 200 records spanning the last 2000 years, a subset of a larger effort to synthesize climate records in NA during the entire Holocene. We identify continent-wide spatial climate patterns during the MCA and LIA, and we compare the differences between the MCA and LIA in our proxy-diverse synthesis to other paleodata-based syntheses and model simulations of these time periods.