I use a range of proxies (plant macrofossils, pollen, charcoal, stable isotopes) to interpret climate and landscape change over centennial to millennial timescales. Current topics include responses to abrupt permafrost thaw, sea-level rise, sea-ice retreat, and centennial-scale land-use change.
Education and Certifications
Columbia University, PhD, 2008
Columbia University, MPhil, 2006
Columbia University, M. A., 2005
Barnard College, A.B., 2002, Magna Cum Laude
Science and Products
Wetlands in the Quaternary
Wetlands accumulate organic-rich sediment or peat stratigraphically, making them great archives of past environmental change. Wetlands also act as hydrologic buffers on the landscape and are important to global biogeochemical cycling. This project uses wetland archives from a range of environments to better understand how vegetation, hydrology, and hydroclimate has changed on decadal to multi...
Wetlands in the Quaternary Project
Wetlands accumulate organic-rich sediment or peat stratigraphically, making them great archives of past environmental change. Wetlands also act as hydrologic buffers on the landscape and are important to global biogeochemical cycling. This project uses wetland archives from a range of environments to better understand how vegetation, hydrology, and hydroclimate has changed on decadal to multi...
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 and
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
Carbon budget assessment of tidal freshwater forested wetland and oligohaline marsh ecosystems along the Waccamaw and Savannah rivers, U.S.A. (2005-2016)
Data to support carbon (C) budget assessment of tidal freshwater forested wetland and oligohaline marsh ecosystems along the Waccamaw and Savannah rivers, U.S.A. This work represents the first estimates of C standing stocks, C mass balance, soil C burial, and lateral C export to aquatic environments in tidal freshwater forested wetlands undergoing transition to oligohaline marsh.
Filter Total Items: 39
Permafrost and climate change: Carbon cycle feedbacks from the warming Arctic
Rapid Arctic environmental change affects the entire Earth system as thawing permafrost ecosystems release greenhouse gases to the atmosphere. Understanding how much permafrost carbon will be released, over what time frame, and what the relative emissions of carbon dioxide and methane will be is key for understanding the impact on global climate. In addition, the response of vegetation in a warmin
Hydrologic controls on peat permafrost and carbon processes: New insights from past and future modeling
Soil carbon (C) in permafrost peatlands is vulnerable to decomposition with thaw under a warming climate. The amount and form of C loss likely depends on the site hydrology following permafrost thaw, but antecedent conditions during peat accumulation are also likely important. We test the role of differing hydrologic conditions on rates of peat accumulation, permafrost formation, and response to w
Influence of permafrost type and site history on losses of permafrost carbon after thaw
We quantified permafrost peat plateau and post-thaw carbon (C) stocks across a chronosequence in Interior Alaska to evaluate the amount of C lost with thaw. Macrofossil reconstructions revealed three stratigraphic layers of peat: (1) a base layer of fen/marsh peat, (2) peat from a forested peat plateau (with permafrost) and, (3) collapse-scar bog peat (at sites where permafrost thaw has occurred).
Permafrost thaw in northern peatlands: Rapid changes in ecosystem and landscape functions
Peatlands within the northern permafrost region cover approximately 2 million km2 and are characterized by organic soils that can be several meters thick, and a fine-scale mosaic of permafrost and non-permafrost landforms interspersed by shallow ponds and lakes. Ongoing permafrost thaw is transforming these peatlands, causing abrupt changes to their morphology, hydrology, ecology, and biogeochemis
Predicted vulnerability of carbon in permafrost peatlands With future climate change and permafrost thaw in western Canada
Climate warming in high-latitude regions is thawing carbon-rich permafrost soils, which can release carbon to the atmosphere and enhance climate warming. Using a coupled model of long-term peatland dynamics (Holocene Peat Model, HPM-Arctic), we quantify the potential loss of carbon with future climate warming for six sites with differing climates and permafrost histories in Northwestern Canada. We
Carbon fluxes and microbial activities from boreal peatlands experiencing permafrost thaw
Permafrost thaw in northern ecosystems may cause large quantities of carbon (C) to move from soil to atmospheric pools. Because soil microbial communities play a critical role in regulating C fluxes from soils, we examined microbial activity and greenhouse gas production soon after permafrost thaw and ground collapse (into collapse-scar bogs), relative to the permafrost plateau or older thaw featu
USGS permafrost research determines the risks of permafrost thaw to biologic and hydrologic resources
The U.S. Geological Survey (USGS), in collaboration with university, Federal, Tribal, and independent partners, conducts fundamental research on the distribution, vulnerability, and importance of permafrost in arctic and boreal ecosystems. Scientists, land managers, and policy makers use USGS data to help make decisions for development, wildlife habitat, and other needs. Native villages and cities
By
Natural Hazards, Water Resources, Earth Resources Observation and Science Center, Climate Research and Development Program, Coastal and Marine Hazards and Resources Program, Land Change Science Program, Volcano Hazards, Earth Resources Observation and Science (EROS) Center , Geology, Geophysics, and Geochemistry Science Center, Geology, Minerals, Energy, and Geophysics Science Center, Geosciences and Environmental Change Science Center, Pacific Coastal and Marine Science Center, Volcano Science Center
Spatiotemporal patterns of northern lake formation since the last glacial maximum
The northern mid- to high-latitudes have the highest total number and area of lakes on Earth. Lake origins in these regions are diverse, but to a large extent coupled to glacial, permafrost, and peatland histories. The synthesis of 1207 northern lake initiation records presented here provides an analog for rapid landscape-level change in response to climate warming, and its subsequent attenuation
Subsea permafrost carbon stocks and climate change sensitivity estimated by expert assessment
The continental shelves of the Arctic Ocean and surrounding seas contain large stocks of organic matter (OM) and methane (CH4), representing a potential ecosystem feedback to climate change not included in international climate agreements. We performed a structured expert assessment with 25 permafrost researchers to combine quantitative estimates of the stocks and sensitivity of organic carbon in
Expert assessment of future vulnerability of the global peatland carbon sink
The carbon balance of peatlands is predicted to shift from a sink to a source this century. However, peatland ecosystems are still omitted from the main Earth system models that are used for future climate change projections, and they are not considered in integrated assessment models that are used in impact and mitigation studies. By using evidence synthesized from the literature and an expert el
High sensitivity of Bering Sea winter sea ice to winter insolation and carbon dioxide over the last 5,500 years
Anomalously low winter sea ice extent and early retreat in CE 2018 and 2019 challenge previous notions that winter sea ice in the Bering Sea has been stable over the instrumental record, although long-term records remain limited. Here, we use a record of peat cellulose oxygen isotopes from St. Matthew Island along with isotope-enabled general circulation model (IsoGSM) simulations to generate a 55
Large stocks of peatland carbon and nitrogen are vulnerable to permafrost thaw
Over many millennia, northern peatlands have accumulated large amounts of carbon and nitrogen, thus cooling the global climate. Over shorter timescales, peatland disturbances can trigger losses of peat and release of greenhouses gases. Despite their importance to the global climate, peatlands remain poorly mapped, and the vulnerability of permafrost peatlands to warming is uncertain. This study co
Science and Products
- Science
Wetlands in the Quaternary
Wetlands accumulate organic-rich sediment or peat stratigraphically, making them great archives of past environmental change. Wetlands also act as hydrologic buffers on the landscape and are important to global biogeochemical cycling. This project uses wetland archives from a range of environments to better understand how vegetation, hydrology, and hydroclimate has changed on decadal to multi...Wetlands in the Quaternary Project
Wetlands accumulate organic-rich sediment or peat stratigraphically, making them great archives of past environmental change. Wetlands also act as hydrologic buffers on the landscape and are important to global biogeochemical cycling. This project uses wetland archives from a range of environments to better understand how vegetation, hydrology, and hydroclimate has changed on decadal to multi... - Data
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 andRadiocarbon 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 macrofossilsCarbon budget assessment of tidal freshwater forested wetland and oligohaline marsh ecosystems along the Waccamaw and Savannah rivers, U.S.A. (2005-2016)
Data to support carbon (C) budget assessment of tidal freshwater forested wetland and oligohaline marsh ecosystems along the Waccamaw and Savannah rivers, U.S.A. This work represents the first estimates of C standing stocks, C mass balance, soil C burial, and lateral C export to aquatic environments in tidal freshwater forested wetlands undergoing transition to oligohaline marsh. - Multimedia
- Publications
Filter Total Items: 39
Permafrost and climate change: Carbon cycle feedbacks from the warming Arctic
Rapid Arctic environmental change affects the entire Earth system as thawing permafrost ecosystems release greenhouse gases to the atmosphere. Understanding how much permafrost carbon will be released, over what time frame, and what the relative emissions of carbon dioxide and methane will be is key for understanding the impact on global climate. In addition, the response of vegetation in a warminHydrologic controls on peat permafrost and carbon processes: New insights from past and future modeling
Soil carbon (C) in permafrost peatlands is vulnerable to decomposition with thaw under a warming climate. The amount and form of C loss likely depends on the site hydrology following permafrost thaw, but antecedent conditions during peat accumulation are also likely important. We test the role of differing hydrologic conditions on rates of peat accumulation, permafrost formation, and response to wInfluence of permafrost type and site history on losses of permafrost carbon after thaw
We quantified permafrost peat plateau and post-thaw carbon (C) stocks across a chronosequence in Interior Alaska to evaluate the amount of C lost with thaw. Macrofossil reconstructions revealed three stratigraphic layers of peat: (1) a base layer of fen/marsh peat, (2) peat from a forested peat plateau (with permafrost) and, (3) collapse-scar bog peat (at sites where permafrost thaw has occurred).Permafrost thaw in northern peatlands: Rapid changes in ecosystem and landscape functions
Peatlands within the northern permafrost region cover approximately 2 million km2 and are characterized by organic soils that can be several meters thick, and a fine-scale mosaic of permafrost and non-permafrost landforms interspersed by shallow ponds and lakes. Ongoing permafrost thaw is transforming these peatlands, causing abrupt changes to their morphology, hydrology, ecology, and biogeochemisPredicted vulnerability of carbon in permafrost peatlands With future climate change and permafrost thaw in western Canada
Climate warming in high-latitude regions is thawing carbon-rich permafrost soils, which can release carbon to the atmosphere and enhance climate warming. Using a coupled model of long-term peatland dynamics (Holocene Peat Model, HPM-Arctic), we quantify the potential loss of carbon with future climate warming for six sites with differing climates and permafrost histories in Northwestern Canada. WeCarbon fluxes and microbial activities from boreal peatlands experiencing permafrost thaw
Permafrost thaw in northern ecosystems may cause large quantities of carbon (C) to move from soil to atmospheric pools. Because soil microbial communities play a critical role in regulating C fluxes from soils, we examined microbial activity and greenhouse gas production soon after permafrost thaw and ground collapse (into collapse-scar bogs), relative to the permafrost plateau or older thaw featuUSGS permafrost research determines the risks of permafrost thaw to biologic and hydrologic resources
The U.S. Geological Survey (USGS), in collaboration with university, Federal, Tribal, and independent partners, conducts fundamental research on the distribution, vulnerability, and importance of permafrost in arctic and boreal ecosystems. Scientists, land managers, and policy makers use USGS data to help make decisions for development, wildlife habitat, and other needs. Native villages and citiesByNatural Hazards, Water Resources, Earth Resources Observation and Science Center, Climate Research and Development Program, Coastal and Marine Hazards and Resources Program, Land Change Science Program, Volcano Hazards, Earth Resources Observation and Science (EROS) Center , Geology, Geophysics, and Geochemistry Science Center, Geology, Minerals, Energy, and Geophysics Science Center, Geosciences and Environmental Change Science Center, Pacific Coastal and Marine Science Center, Volcano Science CenterSpatiotemporal patterns of northern lake formation since the last glacial maximum
The northern mid- to high-latitudes have the highest total number and area of lakes on Earth. Lake origins in these regions are diverse, but to a large extent coupled to glacial, permafrost, and peatland histories. The synthesis of 1207 northern lake initiation records presented here provides an analog for rapid landscape-level change in response to climate warming, and its subsequent attenuationSubsea permafrost carbon stocks and climate change sensitivity estimated by expert assessment
The continental shelves of the Arctic Ocean and surrounding seas contain large stocks of organic matter (OM) and methane (CH4), representing a potential ecosystem feedback to climate change not included in international climate agreements. We performed a structured expert assessment with 25 permafrost researchers to combine quantitative estimates of the stocks and sensitivity of organic carbon inExpert assessment of future vulnerability of the global peatland carbon sink
The carbon balance of peatlands is predicted to shift from a sink to a source this century. However, peatland ecosystems are still omitted from the main Earth system models that are used for future climate change projections, and they are not considered in integrated assessment models that are used in impact and mitigation studies. By using evidence synthesized from the literature and an expert elHigh sensitivity of Bering Sea winter sea ice to winter insolation and carbon dioxide over the last 5,500 years
Anomalously low winter sea ice extent and early retreat in CE 2018 and 2019 challenge previous notions that winter sea ice in the Bering Sea has been stable over the instrumental record, although long-term records remain limited. Here, we use a record of peat cellulose oxygen isotopes from St. Matthew Island along with isotope-enabled general circulation model (IsoGSM) simulations to generate a 55Large stocks of peatland carbon and nitrogen are vulnerable to permafrost thaw
Over many millennia, northern peatlands have accumulated large amounts of carbon and nitrogen, thus cooling the global climate. Over shorter timescales, peatland disturbances can trigger losses of peat and release of greenhouses gases. Despite their importance to the global climate, peatlands remain poorly mapped, and the vulnerability of permafrost peatlands to warming is uncertain. This study co - News