J M Welker
Biographic Data
| ID | 5597924 |
|---|---|
| NAME | J M Welker |
| GIVEN NAMES | J M |
| FAMILY NAME | Welker |
| SIGNATURE | WELKER J M |
| AFFILIATIONS | University of Alaska Anchorage |
| ORCID | 0000-0002-3865-4822 |
| VERIFIED | Yes |
| TOTAL WORKS | 17 |
| TOTAL CITATIONS | 3 |
| WORKS AS AUTHOR | 17 |
| WORKS AS EDITOR | 0 |
| FIRST PUBLICATION YEAR | 2005 |
| LATEST PUBLICATION YEAR | 2025 |
| H-INDEX | 1 |
Arctic surface snow interactions with the atmosphere
Snow on sea ice is crucial in moderating sea ice and atmosphere interactions, yet fully grasping snow’s isotopic composition and the processes shaping it presents substantial challenges, including sublimation and wind redistribution. This study utilizes a year of stable water isotope datasets from the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition in 2019/2020 to explore the complex interactions between…
Changing Winter Landscapes
Snow is a crucial part in the lives of Sámi reindeer herders, and changes in snow conditions can affect their well-being in multiple ways. However, meanings and emotions associated with snow are rarely considered in research on reindeer herding and climate change. Based on thematic interviews with reindeer herders in two reindeer herding co-operatives in the Sámi Homeland in Finland, we examined the roles and meanings of snow for Sámi reindeer he…
Isotopic signatures of snow, sea ice, and surface seawater in the central Arctic Ocean during the MosaiC expedition
The Arctic Ocean is an exceptional environment where hydrosphere, cryosphere, and atmosphere are closely interconnected. Changes in sea-ice extent and thickness affect ocean currents, as well as moisture and heat exchange with the atmosphere. Energy and water fluxes impact the formation and melting of sea ice and snow cover. Here, we present a comprehensive statistical analysis of the stable water isotopes of various hydrological components in th…
Complexity of Arctic Ocean water isotope (δ18O, δ2H) spatial and temporal patterns revealed with machine learning
The stable isotope compositions of water (δ18O, δ2H, deuterium-excess) are important tracers that help illuminate the changing Arctic water cycle and how Arctic-sourced water can influence lower latitudes. We present simultaneous boundary layer water vapor and ocean water isotope data that were measured continuously in the western Arctic Ocean. Sea surface water isotopes varied between the shallower continental Chukchi Shelf and the deeper Chukch…
Climate change, cultural continuity and ecological grief
Arctic regions are warming significantly faster than other parts of the globe, leading to changes in snow, ice and weather conditions, ecosystems and local cultures. These changes have brought worry and concern and triggered feelings of loss among Arctic Indigenous Peoples and local communities. Recently, research has started to address emotional and social dimensions of climate change, framed through the concept of ecological grief. In this stud…
Strontium Isotope Analysis, the Neonatal Line, and Archaeological Caribou Herd Identity in Northwest Alaska
Rangifer tarandus is a keystone species in the Arctic and has shaped human land use in this region for tens of thousands of years. The migratory ecotype requires large landscapes and long migrations between summer and winter ranges to meet their nutritional needs. The extent to which these ranges have remained the same has been controversial and uncertain. Archaeological caribou herd identity is usually ascribed based on modern caribou herd distr…
Time-Integrated Collection of Co 2 for 14 C Analysis From Soils
We developed a passive sampler for time-integrated collection and radiocarbon ( 14 C) analysis of soil respiration, a major flux in the global C cycle. It consists of a permanent access well that controls the CO 2 uptake rate and an exchangeable molecular sieve CO 2 trap. We tested how access well dimensions and environmental conditions affect collected CO 2 , and optimized cleaning procedures to minimize 14 CO 2 memory. We also deployed two gene…
Cloud cover and delayed herbivory relative to timing of spring onset interact to dampen climate change impacts on net ecosystem exchange in a coastal Alaskan wetland
Rapid warming in northern ecosystems over the past four decades has resulted in earlier spring, increased precipitation, and altered timing of plant–animal interactions, such as herbivory. Advanced spring phenology can lead to longer growing seasons and increased carbon (C) uptake. Greater precipitation coincides with greater cloud cover possibly suppressing photosynthesis. Timing of herbivory relative to spring phenology influences plant biomass…
Exploring stakeholder communication within a caribou hunting system of Arctic Alaska
The Central Arctic Caribou (Rangifer tarandus) Herd (CACH) of Arctic Alaska rapidly declined (approximately 70%) between 2010–2016, which has generated hunter concerns and more conservative hunting regulations. Stakeholders expressed interest in exploring opportunities for a more effective exchange of information to facilitate management. We conducted a survey to identify hunters’ insights into CACH dynamics and to estimate the extent and effecti…
Biomass offsets little or none of permafrost carbon release from soils, streams, and wildfire
As the permafrost region warms, its large organic carbon pool will be increasingly vulnerable to decomposition, combustion, and hydrologic export. Models predict that some portion of this release will be offset by increased production of Arctic and boreal biomass; however, the lack of robust estimates of net carbon balance increases the risk of further overshooting international emissions targets. Precise empirical or model-based assessments of t…
Deepened winter snow increases stem growth and alters stem δ 13 C and δ 15 N in evergreen dwarf shrub Cassiope tetragona in high-arctic Svalbard tundra
nDeeper winter snow is hypothesized to favor shrub growth and may partly explain the shrub expansion\nobserved in many parts of the arctic during the last decades, potentially triggering biophysical\nfeedbacks including regional warming and permafrost thawing.Weexperimentally tested the effects\nof winter snow depth on shrub growth and ecophysiology by measuring stem length and stem\nhydrogen (δ2H), carbon (δ13C), nitrogen (δ15N) and oxygen (δ18O…
Shrub expansion in tundra ecosystems
Recent research using repeat photography, long-term ecological monitoring and dendrochronology has documented shrub expansion in arctic, high-latitude and alpine tundra ecosystems. Here, we (1) synthesize these findings, (2) present a conceptual framework that identifies mechanisms and constraints on shrub increase, (3) explore causes, feedbacks and implications of the increased shrub cover in tundra ecosystems, and (4) address potential lines of…
Oxygen isotope ratios in Holocene carbonates across a climatic gradient, eastern Washington State, USA
Oxygen isotope ratios of pedogenic carbonates were analyzed along a climatic gradient in the Palouse region of eastern Washington State to evaluate changes in their isotopic composition with changing climate. A modern analog approach was used to assess the relationship between the istotope ratios in the pedogenic carbonates with those in soil water (measured in June when we anticipated carbonate formation might occur because of low soil water con…
Ecological Dynamics Across the Arctic Associated with Recent Climate Change
Assessing the Arctic The Arctic is experiencing some of the most rapid climate change currently under way across the globe, but consequent ecological responses have not been widely reported. At the close of the Fourth International Polar Year, Post et al. (p. 1355 ) review observations on ecological impacts in this sensitive region. The widespread changes occurring in terrestrial, freshwater, and marine systems, presage changes at lower latitudes…
Global patterns of foliar nitrogen isotopes and their relationships with climate, mycorrhizal fungi, foliar nutrient concentrations, and nitrogen availability
Ratios of nitrogen (N) isotopes in leaves could elucidate underlying patterns of N cycling across ecological gradients. To better understand global‐scale patterns of N cycling, we compiled data on foliar N isotope ratios (δ 15 N), foliar N concentrations, mycorrhizal type and climate for over 11 000 plants worldwide. Arbuscular mycorrhizal, ectomycorrhizal, and ericoid mycorrhizal plants were depleted in foliar δ 15 N by 2‰, 3.2‰, 5.9‰, respectiv…
Evidence and Implications of Recent Climate Change in Northern Alaska and Other Arctic Regions
Role of Land-Surface Changes in Arctic Summer Warming
A major challenge in predicting Earth's future climate state is to understand feedbacks that alter greenhouse-gas forcing. Here we synthesize field data from arctic Alaska, showing that terrestrial changes in summer albedo contribute substantially to recent high-latitude warming trends. Pronounced terrestrial summer warming in arctic Alaska correlates with a lengthening of the snow-free season that has increased atmospheric heating locally by abo…
Climate change, cultural continuity and ecological grief
Arctic regions are warming significantly faster than other parts of the globe, leading to changes in snow, ice and weather conditions, ecosystems and local cultures. These changes have brought worry and concern and triggered feelings of loss among Arctic Indigenous Peoples and local communities. Recently, research has started to address emotional and social dimensions of climate change, framed through the concept of ecological grief. In this stud…
Time-Integrated Collection of Co 2 for 14 C Analysis From Soils
We developed a passive sampler for time-integrated collection and radiocarbon ( 14 C) analysis of soil respiration, a major flux in the global C cycle. It consists of a permanent access well that controls the CO 2 uptake rate and an exchangeable molecular sieve CO 2 trap. We tested how access well dimensions and environmental conditions affect collected CO 2 , and optimized cleaning procedures to minimize 14 CO 2 memory. We also deployed two gene…
Evidence and Implications of Recent Climate Change in Northern Alaska and Other Arctic Regions
Role of Land-Surface Changes in Arctic Summer Warming
A major challenge in predicting Earth's future climate state is to understand feedbacks that alter greenhouse-gas forcing. Here we synthesize field data from arctic Alaska, showing that terrestrial changes in summer albedo contribute substantially to recent high-latitude warming trends. Pronounced terrestrial summer warming in arctic Alaska correlates with a lengthening of the snow-free season that has increased atmospheric heating locally by abo…
Ecological Dynamics Across the Arctic Associated with Recent Climate Change
Assessing the Arctic The Arctic is experiencing some of the most rapid climate change currently under way across the globe, but consequent ecological responses have not been widely reported. At the close of the Fourth International Polar Year, Post et al. (p. 1355 ) review observations on ecological impacts in this sensitive region. The widespread changes occurring in terrestrial, freshwater, and marine systems, presage changes at lower latitudes…
Global patterns of foliar nitrogen isotopes and their relationships with climate, mycorrhizal fungi, foliar nutrient concentrations, and nitrogen availability
Ratios of nitrogen (N) isotopes in leaves could elucidate underlying patterns of N cycling across ecological gradients. To better understand global‐scale patterns of N cycling, we compiled data on foliar N isotope ratios (δ 15 N), foliar N concentrations, mycorrhizal type and climate for over 11 000 plants worldwide. Arbuscular mycorrhizal, ectomycorrhizal, and ericoid mycorrhizal plants were depleted in foliar δ 15 N by 2‰, 3.2‰, 5.9‰, respectiv…
Oxygen isotope ratios in Holocene carbonates across a climatic gradient, eastern Washington State, USA
Oxygen isotope ratios of pedogenic carbonates were analyzed along a climatic gradient in the Palouse region of eastern Washington State to evaluate changes in their isotopic composition with changing climate. A modern analog approach was used to assess the relationship between the istotope ratios in the pedogenic carbonates with those in soil water (measured in June when we anticipated carbonate formation might occur because of low soil water con…
Shrub expansion in tundra ecosystems
Recent research using repeat photography, long-term ecological monitoring and dendrochronology has documented shrub expansion in arctic, high-latitude and alpine tundra ecosystems. Here, we (1) synthesize these findings, (2) present a conceptual framework that identifies mechanisms and constraints on shrub increase, (3) explore causes, feedbacks and implications of the increased shrub cover in tundra ecosystems, and (4) address potential lines of…
Deepened winter snow increases stem growth and alters stem δ 13 C and δ 15 N in evergreen dwarf shrub Cassiope tetragona in high-arctic Svalbard tundra
nDeeper winter snow is hypothesized to favor shrub growth and may partly explain the shrub expansion\nobserved in many parts of the arctic during the last decades, potentially triggering biophysical\nfeedbacks including regional warming and permafrost thawing.Weexperimentally tested the effects\nof winter snow depth on shrub growth and ecophysiology by measuring stem length and stem\nhydrogen (δ2H), carbon (δ13C), nitrogen (δ15N) and oxygen (δ18O…
Biomass offsets little or none of permafrost carbon release from soils, streams, and wildfire
As the permafrost region warms, its large organic carbon pool will be increasingly vulnerable to decomposition, combustion, and hydrologic export. Models predict that some portion of this release will be offset by increased production of Arctic and boreal biomass; however, the lack of robust estimates of net carbon balance increases the risk of further overshooting international emissions targets. Precise empirical or model-based assessments of t…
Cloud cover and delayed herbivory relative to timing of spring onset interact to dampen climate change impacts on net ecosystem exchange in a coastal Alaskan wetland
Rapid warming in northern ecosystems over the past four decades has resulted in earlier spring, increased precipitation, and altered timing of plant–animal interactions, such as herbivory. Advanced spring phenology can lead to longer growing seasons and increased carbon (C) uptake. Greater precipitation coincides with greater cloud cover possibly suppressing photosynthesis. Timing of herbivory relative to spring phenology influences plant biomass…
Exploring stakeholder communication within a caribou hunting system of Arctic Alaska
The Central Arctic Caribou (Rangifer tarandus) Herd (CACH) of Arctic Alaska rapidly declined (approximately 70%) between 2010–2016, which has generated hunter concerns and more conservative hunting regulations. Stakeholders expressed interest in exploring opportunities for a more effective exchange of information to facilitate management. We conducted a survey to identify hunters’ insights into CACH dynamics and to estimate the extent and effecti…
Time-Integrated Collection of Co 2 for 14 C Analysis From Soils
We developed a passive sampler for time-integrated collection and radiocarbon ( 14 C) analysis of soil respiration, a major flux in the global C cycle. It consists of a permanent access well that controls the CO 2 uptake rate and an exchangeable molecular sieve CO 2 trap. We tested how access well dimensions and environmental conditions affect collected CO 2 , and optimized cleaning procedures to minimize 14 CO 2 memory. We also deployed two gene…
Strontium Isotope Analysis, the Neonatal Line, and Archaeological Caribou Herd Identity in Northwest Alaska
Rangifer tarandus is a keystone species in the Arctic and has shaped human land use in this region for tens of thousands of years. The migratory ecotype requires large landscapes and long migrations between summer and winter ranges to meet their nutritional needs. The extent to which these ranges have remained the same has been controversial and uncertain. Archaeological caribou herd identity is usually ascribed based on modern caribou herd distr…
Isotopic signatures of snow, sea ice, and surface seawater in the central Arctic Ocean during the MosaiC expedition
The Arctic Ocean is an exceptional environment where hydrosphere, cryosphere, and atmosphere are closely interconnected. Changes in sea-ice extent and thickness affect ocean currents, as well as moisture and heat exchange with the atmosphere. Energy and water fluxes impact the formation and melting of sea ice and snow cover. Here, we present a comprehensive statistical analysis of the stable water isotopes of various hydrological components in th…
Complexity of Arctic Ocean water isotope (δ18O, δ2H) spatial and temporal patterns revealed with machine learning
The stable isotope compositions of water (δ18O, δ2H, deuterium-excess) are important tracers that help illuminate the changing Arctic water cycle and how Arctic-sourced water can influence lower latitudes. We present simultaneous boundary layer water vapor and ocean water isotope data that were measured continuously in the western Arctic Ocean. Sea surface water isotopes varied between the shallower continental Chukchi Shelf and the deeper Chukch…
Climate change, cultural continuity and ecological grief
Arctic regions are warming significantly faster than other parts of the globe, leading to changes in snow, ice and weather conditions, ecosystems and local cultures. These changes have brought worry and concern and triggered feelings of loss among Arctic Indigenous Peoples and local communities. Recently, research has started to address emotional and social dimensions of climate change, framed through the concept of ecological grief. In this stud…
Arctic surface snow interactions with the atmosphere
Snow on sea ice is crucial in moderating sea ice and atmosphere interactions, yet fully grasping snow’s isotopic composition and the processes shaping it presents substantial challenges, including sublimation and wind redistribution. This study utilizes a year of stable water isotope datasets from the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition in 2019/2020 to explore the complex interactions between…
Changing Winter Landscapes
Snow is a crucial part in the lives of Sámi reindeer herders, and changes in snow conditions can affect their well-being in multiple ways. However, meanings and emotions associated with snow are rarely considered in research on reindeer herding and climate change. Based on thematic interviews with reindeer herders in two reindeer herding co-operatives in the Sámi Homeland in Finland, we examined the roles and meanings of snow for Sámi reindeer he…
Environmental Science (14 works) · Geography (14 works) · Arctic (10 works) · Biology (9 works) · Climate change and permafrost (9 works) · Ecology (8 works) · Geology (8 works) · Physical geography (8 works) · Climate change (7 works) · Cryospheric studies and observations (7 works)