FILLING THE NORTHERN INLAND GAP: POLLEN-INFERRED, HOLOCENE, PALEOCLIMATIC RECONSTRUCTIONS FROM VERMONT

Records from eastern and southern portions of New England and from the Great Lakes region document both Holocene- and centennial-scale changes in precipitation and highlight coastal versus inland climatic gradients. Vermont is centrally located between these regions and previously has represented a gap in paleoclimate data. This study presents a new 13.0 cal ka BP pollen record from Twin Ponds, VT, which is used with the modern analogue technique to provide a new climatic reconstruction. A second climatic reconstruction using a previously published pollen record from nearby Knob Hill Pond provides a regional comparison. The results show several consistent early Holocene trends, including a rapid increase in mean annual temperatures between 11.0 and 11.8 cal ka BP, the warmest mean annual temperatures between 10.8 and 8.2 cal ka BP, and a rapid increase in total annual precipitation starting at 8.2 cal ka BP. Total annual precipitation continued to increase and reached near modern levels by ca. 5.0 cal ka BP and then stayed high until 3.3 cal ka BP. Reconstructions also show a decrease in mean annual temperature during the mid-Holocene between 6.3-8.3 cal ka BP and again from 5.6-3.3 cal ka BP. The late-Holocene (ca. 0.2-3.0 cal ka BP) was cooler and drier than present and during the last 200 years there was an increase in both precipitation and temperature. On centennial time-scales there were several minor (within 1⁰ C) shifts in mean annual temperature that are seen in both reconstructions, however, shifts in total annual precipitation are not as well correlated. Lake-level reconstructions from southern New England show an increase in moisture starting between 9.0 and 10.0 cal ka BP, prior to those in Vermont, and a Holocene trend of increasing moisture punctuated by periodic droughts. Several of the droughts documented at inland sites in southern New England are also seen in at least one the Vermont reconstructions, however, these similarities diverge after ca. 1.5 cal ka BP when southern regions show an increase in moisture and Vermont records show a decline. Further analysis will focus on the seasonality of climate change and the coherency of centennial-scale climate changes between the two records.