PRELIMINARY RESULTS OF A NOVEL MULTI-PROXY CLIMATE SYNTHESIS APPROACH FROM THE NORTH AMERICAN HOLOCENE CLIMATE SYNTHESIS WORKING GROUP

Spatially robust abrupt climate events punctuate the Holocene climate record in numerous North American paleoclimate reconstructions. However, the mechanisms driving these events and their exact timing, spatial extent, and magnitude across the continent remain unclear. We have established a working group that will utilize the wealth of climate history information from a variety of terrestrial and coastal marine environments in North America to reveal the patterns of Holocene climate-driven proxy changes.

Synthesizing paleoclimate data is challenging due to: 1) the wide range of sensitivities of different proxy types to environmental variables, 2) indirect relationships between certain proxies and climatic variables, 3) a paucity of records with the temporal resolution and timespan that are appropriate for the hypotheses being tested, and 4) maintaining a spatial distribution and density of records that is appropriate to accurately identify spatial climate gradients and boundaries. Limiting proxy types and/or including records with only high temporal resolution may limit our understanding of the character of climate variations due to differences in sensitivities and rate of response between different proxy types and the inability to capture centennial and longer climate variations in short, highly-resolved records. In an effort to capture the full range of climate variations over the Holocene, we include a broad selection of lithological, geochemical, and biological proxies from a wide range of environments, including several types of terrestrial sedimentary archives, coastal marine sediments, ice cores, and speleothems.

We present the preliminary results of our North American Holocene climate synthesis, specifically surrounding some of the climate events highlighted by this session. Additionally, we identify key regions where additional paleoclimate reconstructions are needed to improve synthesis efforts.