Publication Abstracts

Kneller 1996

Kneller, M.L., 1996: Paleoclimate from the Last Glacial Maximum to the Present: Pollen and Plant Macrofossil Records from the United States Southeast Accompanied by a Goddard Institute for Space Studies General Circulation Model Simulation. Ph.D. thesis. Columbia University.

The timing and direction of climate change, from the last glacial maximum (LGM) into the Holocene, is investigated at a new site in the North American central Appalachians which dates to 17,130 14C yr BP, Browns Pond, Virginia. Pollen and plant macrofossil profiles from a transect of cores, chronologically constrained with accelerator mass spectrometry radiocarbon dates on both macrofossils and bulk sediment, provides evidence for a closed Picea-Abies-Pinus forest at the LGM. More Alnus at 14,100 14C yr BP may be caused by increased wetness. Shifts towards warmer climate at 12,700 and 11,300 14C yr BP are inferred from increases in temperate hardwood pollen taxa, and Tsuga pollen and needles, respectively. Rising Nyssa and Quercus pollen at 10,000 14C yr BP, and Diospyrus at 8890 14C yr BP are evidence for additional warming at these times. The present-day Quercus-Pinus assemblage is established at 7500 14C yr BP. Cold reversals are centered at 12,240 and 7500 14C yr BP—cold-tolerant conifer taxa increase.

A new simulation of LGM climate with the Goddard Institute for Space Studies (GISS) General Circulation Model (GCM) is compared with older LGM simulations, and with climate conditions interpreted from existing U.S. southeast paleovegation records. This simulation of the LGM climate, with fixed CLIMAP sea surface temperatures (SSTs), utilizes a Model II prime version of the GISS GCM. Model II prime incorporates substantial changes in model physics and numerics at a 4° by 5° resolution. Compared to existing Model II LGM simulations, surface air temperatures are colder over snow-covered regions. Initial results suggest that the snow albedo parameterization has a major effect upon the high-latitude surface air temperatures which, given the fixed SSTs, forces changes in global cloud cover and water vapor distribution. In this Model II prime simulation, cooler temperatures are most clearly evident only adjacent to the ice margin.

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BibTeX Citation

@phdthesis{kn02100q,
  author={Kneller, M. L.},
  title={Paleoclimate from the Last Glacial Maximum to the Present: Pollen and Plant Macrofossil Records from the United States Southeast Accompanied by a Goddard Institute for Space Studies General Circulation Model Simulation},
  year={1996},
  school={Columbia University},
  address={New York, N.Y.},
}

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RIS Citation

TY  - THES
ID  - kn02100q
AU  - Kneller, M. L.
PY  - 1996
BT  - Paleoclimate from the Last Glacial Maximum to the Present: Pollen and Plant Macrofossil Records from the United States Southeast Accompanied by a Goddard Institute for Space Studies General Circulation Model Simulation
PB  - Columbia University
CY  - New York, N.Y.
ER  -

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