A5082117666- Climate change and permafrost
- Methane Hydrates and Related Phenomena
- Geology and Paleoclimatology Research
- Atmospheric and Environmental Gas Dynamics
- Cryospheric studies and observations
- Peatlands and Wetlands Ecology
- Coastal wetland ecosystem dynamics
- Indigenous Studies and Ecology
- Soil Carbon and Nitrogen Dynamics
- Soil Geostatistics and Mapping
- Image Processing and 3D Reconstruction
- Soil and Unsaturated Flow
- Isotope Analysis in Ecology
- Archaeology and ancient environmental studies
- Pleistocene-Era Hominins and Archaeology
- Environmental Conservation and Management
- Hydrocarbon exploration and reservoir analysis
- Land Use and Ecosystem Services
- Geographies of human-animal interactions
- Conservation, Biodiversity, and Resource Management
- Coastal and Marine Dynamics
- Tropical and Extratropical Cyclones Research
University of California, Berkeley
2016-2025
Lawrence Berkeley National Laboratory
2016-2025
San Francisco Estuary Institute
2020-2024
Soil is the largest terrestrial carbon reservoir and may influence sign magnitude of cycle–climate feedbacks. Many Earth system models (ESMs) estimate a significant soil sink by 2100, yet underlying dynamics determining this response have not been systematically tested against observations. We used 14 C data from 157 globally distributed profiles sampled to 1-meter depth show that ESMs underestimated mean age factor more than six (430 ± 50 years versus 3100 1800 years). Consequently,...
Abstract. Radiocarbon is a critical constraint on our estimates of the timescales soil carbon cycling that can aid in identifying mechanisms stabilization and destabilization improve forecast response to management or environmental change. Despite wealth radiocarbon data have been reported over past 75 years, ability apply these global-scale questions limited by capacity synthesize compare measurements generated using variety methods. Here, we present International Soil Database (ISRaD;...
Abstract Soils are warming as air temperatures rise across the Arctic and Boreal region concurrent with expansion of tall-statured shrubs trees in tundra. Changes vegetation structure function expected to alter soil thermal regimes, thereby modifying climate feedbacks related permafrost thaw carbon cycling. However, current understanding impacts on temperature is limited local or regional scales lacks generality necessary predict stability a pan-Arctic scale. Here we synthesize shallow...
Arctic wetlands are currently net sources of atmospheric CH4 . Due to their complex biogeochemical controls and high spatial temporal variability, current emissions gross processes have been difficult quantify, predicted responses climate change remain uncertain. We investigated production, oxidation, surface in polygon tundra, across a wet-to-dry permafrost degradation gradient from low-centered (intact) flat- high-centered (degraded) polygons. From 3 microtopographic positions (polygon...
Humans are changing the Earth's surface at an accelerating pace, with significant consequences for ecosystems and their biodiversity. Landscape transformation has far-reaching implications including reduced net primary production (NPP) available to support ecosystems, energy supplies consumers, disruption of ecosystem services such as carbon storage. Anthropogenic activities have global NPP terrestrial by nearly 25%, but loss from wetland is unknown. We used a simple approach estimate...
Climate warming may accelerate decomposition of Arctic soil carbon, but few controlled experiments have manipulated the entire active layer. To determine surface-atmosphere fluxes carbon dioxide and methane under anticipated end-of-century warming, here we used heating rods to warm (by 3.8 °C) depth permafrost in polygonal tundra Utqiaġvik (formerly Barrow), Alaska measured over two growing seasons. We show that ecosystem respiration is ~30% higher warmed plots than control (0.99 μmol m−2...
Quantitative, broadly applicable metrics of resilience are needed to effectively manage tidal marshes into the future. Here we quantified three temporal marsh resilience: time drowning, tipping point, and probability a regime shift, defined as conditional transition an alternative super-optimal, suboptimal, or drowned state. We used organic matter content (loss on ignition, LOI) peat age combined with Coastal Wetland Equilibrium Model (CWEM) track wetland development under different...
Abstract. Radiocarbon measurements of ecosystem respiration and soil pore space CO2 are useful for determining the sources respiration, identifying environmental controls on carbon cycling rates, parameterizing evaluating models cycle. We measured flux rates radiocarbon content as well in profile Utqiaġvik (Barrow), Alaska, during summers 2012, 2013, 2014. found that (Δ14CReco) ranged from +60.5 to −160 ‰ with a median value +23.3 ‰. Ecosystem became more depleted summer autumn, indicating...
Abstract. Radiocarbon is a critical constraint on our estimates of the timescales soil carbon cycling that can aid in identifying mechanisms stabilization and destabilization, improve forecast response to management or environmental change. Despite wealth radiocarbon data has been reported over past 75 years, ability apply these global scale questions limited by capacity synthesis compare measurements generated using variety methods. Here we describe International Soil Database (ISRaD,...
In the Sacramento–San Joaquin Delta (Delta), widespread drainage of historical wetlands has led to extensive subsidence and peat carbon losses, as well high ongoing greenhouse gas (GHG) emissions. Large-scale wetland restoration conversion rice fields potential mitigate these effects while conferring flood protection creating habitat for species. To explore scale benefits, this study evaluated seven Delta-wide land-use scenarios on stocks, land-surface elevation, GHG emissions, habitat. Peat...
Abstract. Radiocarbon measurements of ecosystem respiration and soil pore space CO2 are useful for determining the sources respiration, identifying environmental controls on carbon cycling rates, parameterizing evaluating models. We measured flux rates radiocarbon contents as well in profile Utqiaġvik (Barrow), Alaska, during summers 2012, 2013, 2014. found that ranged from +60.5 to −160 ‰ with a median value +23.3 ‰. Ecosystem became more depleted summer autumn,...
an annually resolved time series of atmospheric Δ 14 C-CO 2 for Barrow, Alaska Datasets used 1.The IntCal13 dataset provides pre-bomb radiocarbon values at 5-year resolution until 1950 (Reimer et al., 2013).2. Radiocarbon measurements made in Fruholmen, Norway cover the period from December 1962 through June 1993 (Nydal and Lövseth, 1996).Limited Point Barrow between 1985 1991 confirm that this a close approximation (Meijer 2008).