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Debra A Willard, Ph.D.

I am a palynologist (pollen and spores) with expertise in paleoecology, paleoclimatology, and biostratigraphy. My biostratigraphic expertise extends from the Carboniferous to the Holocene, with an emphasis on Euramerica (Paleozoic) and the Northern Hemisphere. My paleoclimate expertise includes the late Paleozoic and the Paleogene to Holocene intervals.

Editorial Boards

  • Global and Planetary Change
  • Frontiers in Ecology and Evolution – Paleoecology section Review Editor
  • Quaternary
  • Review of Palaeobotany and Palynology

Professional Experience

  • 2021-Present    Research Geologist, US Geological Survey, Reston, Virginia

  • 2011-2021         Coordinator, USGS Climate Research & Development Program

  • 1991-2011         Research Geologist, US Geological Survey, Reston, Virginia

  • 1990-1991         Postdoctoral Researcher, National Museum of Natural History, Smithsonian Institution, Washington, DC

Education and Certifications

  • University of Illinois at Urbana-Champaign  -  Ph.D., Botany 1990

  • University of Illinois at Urbana-Champaign  -  M.S., Botany 1985

  • The Pennsylvania State University  -  B.S., Botany 1982

  • Stephens College -  A.A., Geology 1980

Affiliations and Memberships*

  • American Geophysical Union

  • Geological Society of America

  • The Palynological Society

Science and Products

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Surveying for the FEMA project

The Influence of Climatic changes on Extreme Streamflows in the United States

Hydrologic droughts and floods can have severe impacts on river infrastructure, water supply, and ecosystem functioning.
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New England Water Science Center
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The Influence of Climatic changes on Extreme Streamflows in the United States

Hydrologic droughts and floods can have severe impacts on river infrastructure, water supply, and ecosystem functioning.
Learn More
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USGS science for a changing world logo

Broader view of North American climate over the past two millennia: Synthesizing paleoclimate records from diverse archives

Regional- to continental-scale paleoclimate syntheses of temperature and hydroclimate in North America are essential for understanding long-term spatiotemporal variability in climate, and for properly assessing risk on decadal and longer timescales. However, existing syntheses rely almost exclusively on tree-ring records, which are known to underestimate low-frequency variability and rarely extend
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John Wesley Powell Center for Analysis and Synthesis
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Broader view of North American climate over the past two millennia: Synthesizing paleoclimate records from diverse archives

Regional- to continental-scale paleoclimate syntheses of temperature and hydroclimate in North America are essential for understanding long-term spatiotemporal variability in climate, and for properly assessing risk on decadal and longer timescales. However, existing syntheses rely almost exclusively on tree-ring records, which are known to underestimate low-frequency variability and rarely extend
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Charcoal data from four sites in Great Dismal Swamp National Wildlife Refuge - August 2022

Charcoal counts and radiocarbon dates from four sediment cores collected in Great Dismal Swamp in 2017 and 2018 were incorporated into a synthesis of charcoal records from northern hemisphere peatlands (Sims et al., in review). Macroscopic charcoal was counted in three size classes: 125-250 micrometers, and 250-500 micrometers, and >500 micrometers. Uncalibrated radiocarbon dates were obtained
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Florence Bascom Geoscience Center

Radiocarbon dates, charcoal, and polycyclic aromatic hydrocarbon (PAH) data from Great Dismal Swamp Sites GDS-519 and GDS-520

Sediment cores were collected in Great Dismal Swamp National Wildlife Refuge in November, 2017 to advance understanding of climate- and land-management driven changes in vegetation, hydrology, and fire regimes. Radiocarbon dates were obtained from samples in two cores (GDS-519-3-21-2017 and GDS-520-3-21-2017) to generate age models for the cores. Bulk sediment samples, charcoal, plant macrofossils
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Florence Bascom Geoscience Center
Scientists are collecting core samples from the Great Dismal Swamp in Virginia
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Scientists are collecting core samples from the Great Dismal Swamp in Virginia
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Scientists are collecting core samples from the Great Dismal Swamp in Virginia
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Photograph of the Great Dismal Swamp in Virginia
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Scientists are collecting core samples from the Great Dismal Swamp in Virginia
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Scientists are collecting core samples from the Great Dismal Swamp in Virginia
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Scientists are collecting core samples from the Great Dismal Swamp in Virginia
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Scientists are collecting core samples from the Great Dismal Swamp in Virginia
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Scientists are collecting core samples from the Great Dismal Swamp in Virginia
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Scientists are collecting core samples from the Great Dismal Swamp in Virginia
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Photograph of the Great Dismal Swamp in Virginia
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Filter Total Items: 104

Regional variability in peatland burning at mid-to high-latitudes during the Holocene

Northern peatlands store globally-important amounts of carbon in the form of partly decomposed plant detritus. Drying associated with climate and land-use change may lead to increased fire frequency and severity in peatlands and the rapid loss of carbon to the atmosphere. However, our understanding of the patterns and drivers of peatland burning on an appropriate decadal to millennial timescale re
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Florence Bascom Geoscience Center

Poleward amplification, seasonal rainfall and forest heterogeneity in the Miocene of the eastern USA

Paleoclimate reconstructions can provide a window into the environmental conditions in Earth history when atmospheric carbon dioxide concentrations were higher than today. In the eastern USA, paleoclimate reconstructions are sparse, because terrestrial sedimentary deposits are rare. Despite this, the eastern USA has the largest population and population density in North America, and understanding
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Florence Bascom Geoscience Center

A 1.8 million year history of Amazon vegetation

During the Pleistocene, long-term trends in global climate were controlled by orbital cycles leading to high amplitude glacial-interglacial variability. The history of Amazonian vegetation during this period is largely unknown since no continuous record from the lowland basin extends significantly beyond the last glacial stage. Here we present a paleoenvironmental record spanning the last 1800 kyr
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Florence Bascom Geoscience Center

Biostratigraphically significant palynofloras from the Paleocene–Eocene boundary of the USA

Pollen and spores were recovered from the Paleocene Fort Union Formation and Paleocene–Eocene Willwood Formation of the Bighorn Basin (BHB), northwestern Wyoming, USA. In many local stratigraphic sections in the BHB, the base of the Eocene has been identified by the characteristic negative carbon isotope excursion (CIE) that marks the beginning of the Paleocene–Eocene Thermal Maximum (PETM). The p
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Climate Research and Development Program, Florence Bascom Geoscience Center

Foreword: Wetland carbon and environmental management

No abstract available.
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Ecosystems, Climate Research and Development Program

Tidal erosion and upstream sediment trapping modulate records of land-use change in a formerly glaciated New England estuary

Land clearing, river impoundments, and other human modifications to the upland landscape and within estuarine systems can drive coastal change at local to regional scales. However, as compared with mid-latitude coasts, the impacts of human modifications along sediment-starved formerly glaciated coastal landscapes are relatively understudied. To address this gap, we present a late-Holocene record o
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Ecosystems, Climate Adaptation Science Centers, Climate Research and Development Program

Application of a regional climate model to assess changes in the climatology of the Eastern US and Cuba associated with historic landcover change

We examine the annual, seasonal, monthly, and diurnal climate responses to the land use change (LUC) in eastern United States and Cuba during four epochs (1650, 1850, 1920, and 1992) with ensemble simulations conducted with the RegCM4 regional climate model that includes the Biosphere Atmosphere Transfer Scheme (BATS1e) surface physics package (Dickinson et al., 1993). We derived the land use (LU)
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Ecosystems, Cooperative Research Units, Earth Resources Observation and Science Center, Earth Resources Observation and Science (EROS) Center , Florence Bascom Geoscience Center, Geosciences and Environmental Change Science Center, Northern Rocky Mountain Science Center

Paleoclimate of the subtropical Andes during the latest Miocene, Lauca Basin, Chile

Uplift of the Andean Cordillera during the Miocene and Pliocene produced large-scale changes in regional atmospheric circulation that impacted local ecosystems. The Lauca Basin (northern Chilean Altiplano) contains variably fluvial and lacustrine sedimentary sequences spanning the interval from 8.7 to 2.3 Ma. Field samples were collected from paleo-lacustrine sediments in the basin. Sediments were
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Ecosystems, Land Change Science Program, Climate Research and Development Program

Rapid inundation of the southern Florida coastline despite low relative sea-level rise rates during the late-Holocene

Sediment cores from Florida Bay, Everglades National Park were examined to determine ecosystem response to relative sea-level rise (RSLR) over the Holocene. High-resolution multiproxy analysis from four sites show freshwater wetlands transitioned to mangrove environments 4–3.6 ka, followed by estuarine environments 3.4–2.8 ka, during a period of enhanced climate variability. We calculate a RSLR ra
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Ecosystems, Natural Hazards, Climate Adaptation Science Centers, Climate Research and Development Program, Coastal and Marine Hazards and Resources Program, Florence Bascom Geoscience Center, St. Petersburg Coastal and Marine Science Center

Arctic vegetation, temperature, and hydrology during Early Eocene transient global warming events

Early Eocene global climate was warmer than much of the Cenozoic and was punctuated by a series of transient warming events or ‘hyperthermals’ associated with carbon isotope excursions when temperature increased by 4–8° C. The Paleocene-Eocene Thermal Maximum (PETM, ~55 Ma) and Eocene Thermal Maximum 2 (ETM2, 53.5 Ma) hyperthermals were of short duration (< 200 kyr) and dramatically restructured t
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Ecosystems, Climate Research and Development Program

The mighty Susquehanna—extreme floods in Eastern North America during the past two millennia

The hazards posed by infrequent major floods to communities along the Susquehanna River and the ecological health of Chesapeake Bay remain largely unconstrained due to the short length of streamgage records. Here we develop a history of high‐flow events on the Susquehanna River during the late Holocene from flood deposits contained in MD99‐2209, a sediment core recovered in 26 m of water from Ches
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Climate Research and Development Program, Land Change Science Program, Chesapeake Bay Activities, Florence Bascom Geoscience Center, Pennsylvania Water Science Center

Geographic attribution of soils using probabilistic modeling of GIS data for forensic search efforts

Examinations of soil traces associated with forensic evidence can be used to narrow potential source area(s) by characterizing features of the trace soil assemblage, some of which are limited to specific regions. Soil characteristics may be used to infer the likelihoods of the soil trace being derived from distinct areas within digital maps, including both maps of discrete classes such as formatio
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Florence Bascom Geoscience Center
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Geologic records of a warmer Arctic

This article is part of the Fall 2019 issue of the Earth Science Matters Newsletter.

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Planning for effective restoration in the Everglades

This article is part of the Fall 2014 issue of the Earth Science Matters Newsletter. 

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Science and Products

*Disclaimer: Listing outside positions with professional scientific organizations on this Staff Profile are for informational purposes only and do not constitute an endorsement of those professional scientific organizations or their activities by the USGS, Department of the Interior, or U.S. Government