A5031915359- Geology and Paleoclimatology Research
- Climate change and permafrost
- Environmental DNA in Biodiversity Studies
- Cryospheric studies and observations
- Metabolomics and Mass Spectrometry Studies
- Methane Hydrates and Related Phenomena
- Isotope Analysis in Ecology
- Groundwater and Isotope Geochemistry
- Microbial Community Ecology and Physiology
- Soil and Water Nutrient Dynamics
- Hydrology and Watershed Management Studies
- Indigenous Studies and Ecology
- Arctic and Antarctic ice dynamics
- Geological Studies and Exploration
- Geological formations and processes
- Hydrocarbon exploration and reservoir analysis
- Fire effects on ecosystems
- Marine and environmental studies
- Lichen and fungal ecology
- Archaeology and ancient environmental studies
- Groundwater flow and contamination studies
- Aeolian processes and effects
- Advancements in Battery Materials
- demographic modeling and climate adaptation
- Water Quality and Resources Studies
University of Wyoming
2024-2025
Institute of Arctic and Alpine Research
2021-2024
University of Colorado Boulder
2021-2024
University of Iceland
2021-2024
University of California, Santa Cruz
2023
University of Colorado System
2019-2023
Lawrence Berkeley National Laboratory
2019-2020
University of California, Berkeley
2019
Abstract Branched glycerol dialkyl tetraethers (brGDGTs) are bacterial membrane lipids that frequently employed as paleoenvironmental proxies because of the strong empirical correlations between their relative abundances and environmental temperature pH. Despite ubiquity brGDGTs in modern paleoenvironments, source organisms these enigmatic compounds have remained elusive, requiring applications to rely solely on observed correlations. Previous laboratory studies suggested globally abundant...
Abstract. Distributions of branched glycerol dialkyl tetraethers (brGDGTs) are frequently employed for reconstructing terrestrial paleotemperatures from lake sediment archives. Although brGDGTs globally ubiquitous, the microbial producers these membrane lipids remain unknown, precluding a full understanding ways in which environmental parameters control their production and distribution. Here, we advance this three ways. First, present 43 new high-latitude sites characterized by low mean...
Bacterial brGDGT lipids are a prevalent tool in studies of terrestrial paleoclimate. Their distributions correlate empirically with environmental temperature and pH, their ubiquity terrestrial, freshwater, marine environments gives them wide applicability. Whether correlations pH emerge due to physiological response source organisms and/or shift bacterial community composition remains an open question important implications for proxy development application. We applied newly described...
Summer warming is driving a greening trend across the Arctic, with potential for large-scale amplification of climate change due to vegetation-related feedbacks [Pearson et al., Nat. Clim. Chang. (3), 673-677 (2013)]. Because observational records are sparse and temporally limited, past episodes Arctic can help elucidate magnitude vegetation response temperature change. The Last Interglacial ([LIG], 129,000 116,000 y ago) was most recent episode on par predicted 21st century [Otto-Bliesner...
The distribution of brGDGT lipids produced by soil bacteria has been used to reconstruct temperatures in marine and terrestrial settings as far back the Cretaceous period. However, modern calibrations this proxy have primarily relied on air rather than situ temperatures, which can differ more 10 °C. Furthermore, influence other parameters such temperature seasonality chemistry is not fully understood. We measured distributions, pH, water content, electrical conductivity soils from Eastern...
Abstract Sedimentary plant wax δ 2 H values are common proxies for hydrology, a poorly constrained variable in the Arctic. However, it can be difficult to distinguish waxes derived from aquatic versus terrestrial plants, causing uncertainty climate interpretations. We test hypothesis that Arctic lake sediment mid‐ and long‐chain derive respectively. compare n ‐alkanoic acid ‐alkane chain‐length distributions 13 C of 29 most abundant modern taxa those soils, water filtrates, sediments Qaupat...
Abstract Major components of hydrologic and elemental cycles reside underground, where their complex dynamics linkages to surface waters are obscure. We delineated seasonal subsurface flow transport along a hillslope in the Rocky Mountains (USA), precipitation occurs primarily as winter snow drainage discharges into East River, tributary Gunnison River. Hydraulic geochemical measurements down 10 m below ground supported application transmissivity feedback snowmelt describe through three...
At an electrode, ions and solvent accumulate to screen charge, leading a nanometer-scale electric double layer (EDL). The EDL guides electrode passivation in batteries, while (super)capacitors, it determines charge storage capacity. Despite its importance, quantification of the potential-dependent remains challenging problem. Here, we directly probe changes composition with potential using situ vibrational spectroscopy molecular dynamics simulations for Li-ion battery electrolyte (LiClO4...
Recent studies in snowmelt-dominated catchments have documented changes nitrogen (N) retention over time, such as declines watershed exports of N, though there is a limited understanding the controlling processes driving these trends. Working mountainous headwater East River Colorado watershed, we explored effects riparian hollows N-cycling hotspots and important small-scale controls on observed Using modeling-based approach informed by remote sensing situ observations, simulated N-retention...
Abstract. Distributions of branched glycerol dialkyl tetraethers (brGDGTs) are frequently employed for reconstructing terrestrial paleotemperatures from lake sediment archives. Although brGDGTs globally ubiquitous, the microbial producers these membrane lipids remain unknown, precluding a full understanding ways in which environmental parameters control their production and distribution. Here, we advance this three ways. First, present 43 new high-latitude sites characterized by low mean...
As the Arctic continues to warm, woody shrubs are expected expand northward. This process, known as ‘shrubification,’ has important implications for regional biodiversity, food web structure, and high-latitude temperature amplification. While future rate of shrubification remains poorly constrained, past records plant immigration newly deglaciated landscapes in may serve useful analogs. We provide one new postglacial Holocene sedimentary ancient DNA ( sed aDNA) record vascular plants from...
Abstract Lacustrine δ 2 H and 18 O isotope proxies are powerful tools for reconstructing past climate precipitation changes in the Arctic. However, robust paleoclimate record interpretations depend on site‐specific lake water systematics, which poorly described eastern Canadian Arctic due to insufficient modern data. We use isotopes (δ H) collected between 1994–1997 2017–2021 from a transect of sites spanning Québec‐to‐Ellesmere Island gradient evaluate effects inflow seasonality evaporative...
Abstract Paleotemperature histories derived from lake sediment archives provide valuable context for modern and future climate changes. Branched glycerol dialkyl tetraether (brGDGT) lipids are a tool in such pursuits due to their empirical correlation with temperature near ubiquity nature. However, the relative contributions of terrestrial lacustrine sources brGDGTs sediments is site‐dependent difficult constrain. Here, we explored potential intact brGDGTs—the complete polar head groups...
Abstract Sediment cores from 13 lakes in a 1500 km transect along the eastern North American Arctic contain up to four superposed stratified interglacial units. All one unit with sediment similar character and mass Holocene gyttja, 14 C ages >40 ka, luminescence 90 120 pollen assemblages that require nearly complete Laurentide deglaciation, supporting Last Interglacial (LIG; MIS 5e) age. Two preserve an older interglacial, suggesting 7 Four adjacent record thin, organic between LIG units...
Abstract. As global warming progresses, changes in high-latitude precipitation are expected to impart long-lasting impacts on earth systems, including glacier mass balance and ecosystem structure. Reconstructing past hydroclimate from networks of continuous lake records offers one way improve forecasts precipitation-evaporation balances, but these reconstructions currently hindered by the incomplete understanding controls soil water isotopes. Here, we study distribution modern isotopes...
ABSTRACT Paleo water isotope records can elucidate how the Arctic cycle responded to past climate changes. We analyze hydrogen composition (δ 2 H) of plant‐derived n ‐alkanoic acids (waxes) from Lake Qaupat, Baffin Island, Nunavut, Canada, assess moisture sources and seasonality during 5.8 ka. compare this record a sedimentary ancient DNA ( sed aDNA)‐inferred vascular plant same lake, aiming overcome uncertainty community impacts on leaf waxes. As aDNA reveals stable after colonization...
Branched Glycerol Dialkyl Tetraethers (brGDGTs) are bacterial membrane lipids that frequently employed as paleoenvironmental proxies because of the strong empirical correlations between their relative abundances and environmental temperature pH.Despite ubiquity brGDGTs in modern paleo environments, source organisms these enigmatic compounds have remained elusive, requiring applications to rely solely on observed correlations.Previous laboratory studies suggested globally abundant phylum...
Abstract. Most extant ice caps mantling low-relief Arctic Canada landscapes remained cold based throughout the late Holocene, preserving in situ bryophytes killed as expanded across vegetated landscapes. After reaching peak Holocene dimensions ∼1900 CE, receded summers warmed, exposing entombed vegetation. The calibrated radiocarbon ages of moss collected near cap margins (kill dates) define when advanced site, killing moss, and over site until year their collection. In an earlier study, we...
Abstract The Arctic has warmed three times the rate of global average, resulting in extensive thaw perennially frozen ground known as permafrost. While it is well understood that permafrost will continue and likely accelerate, rates are nonuniform due, part, to expansion trees tall shrubs may increase temperatures. However, regions with short‐stature vegetation (height < 40 cm), our understanding how temperature regimes vary by type limited these sites generally found remote high‐latitude...
Abstract. Paleoclimate reconstructions across Iceland provide a template for past changes in climate the northern North Atlantic, crucial region due to its position relative global northward heat transport system and vulnerability change. The roles of orbitally driven summer cooling, volcanism, human impact as triggers local environmental Holocene remain debated. While there are indications that may have reduced resilience during late it is still difficult resolve what extent natural factors...