Climate change is forcing dramatic glacier mass loss in the Cordillera Blanca, Peru, resulting in hydrologic transformations across the Rio Santa watershed and increasing human vulnerability. This ...article presents results from two years of transdisciplinary collaborative research evaluating the complex relationships between coupled environmental and social change in the region. First, hydrologic results suggest there has been an average increase of 1.6 (± 1.1) percent in the specific discharge of the more glacier-covered catchments (>20 percent glacier area) as a function of changes in stable isotopes of water (δ
18
O and δ
2
H) from 2004 to 2006. Second, there is a large (mean 60 percent) component of groundwater in dry season discharge based on results from the hydrochemical basin characterization method. Third, findings from extensive key interviews and seventy-two randomly sampled household interviews within communities located in two case study watersheds demonstrate that a large majority of households perceive that glacier recession is proceeding very rapidly and that climate change-related impacts are affecting human vulnerability across multiple shifting vectors including access to water resources, agro-pastoral production, and weather variability.
Soil freeze–thaw processes play a fundamental role in the hydrology, geomorphology, ecology, thermodynamics, and soil chemistry of cold regions' landscapes. In understanding these processes, the ...temperature of the soil is used as a proxy to represent the partitioning of soil ice and water content via a soil freezing characteristic curve (SFCC). This mathematical construct relates the soil ice content to a specific temperature for a particular soil. SFCCs depend on many factors, including soil properties (e.g., porosity and composition), soil pore water pressure, dissolved salts, (hysteresis in) freezing/thawing point depression, and the degree of saturation, all of which can be site-specific and time-varying characteristics. SFCCs have been measured using various methods for diverse soils since 1921, but, to date, these data have not been broadly compared. This is in part because they had not previously been compiled in a single dataset. The dataset presented in this publication includes SFCC data digitized or received from authors, and it includes both historic and modern studies. The data are stored in an open-source repository, and an R package is available to facilitate their use. Aggregating the data has pointed out some data gaps, namely that there are few studies on coarse soils and comparably few in situ measurements of SFCCs in mountainous environments. It is hoped that this dataset (https://doi.org/10.5281/zenodo.5592825; Devoie et al., 2022a) will aid in the development of SFCC theory and improve SFCC approximations in soil freeze–thaw modelling activities.
Tropical glaciers constitute an important source of water for downstream populations. However, our understanding of glacial melt processes is still limited. One observed process that has not yet been ...quantified for tropical glaciers is the enhanced melt caused by the longwave emission transfer. Here, we use high-resolution surface temperatures obtained from the thermal infrared imagery of the Cuchillacocha Glacier, in the Cordillera Blanca, Peru in June 2014 to calculate a margin longwave flux. This longwave flux, reaching the glacier margin from the adjacent exposed rock, varies between 81 and 120 W m−2 daily. This flux is incorporated into a physically-based melt model to assess the net radiation budget at the modeled glacier margin. The simulation results show an increase in the energy available for melt by an average of 106 W m−2 during the day when compared with the simulation where the LW
margin
flux is not accounted for. This value represents an increase in ablation of ~1.7 m at the glacier margin for the duration of the dry season. This study suggests that including the quantification of the glacier margin longwave flux in physically-based melt models results in an improved assessment of tropical glacier energy budget and meltwater generation.
Fire and grazing are two of the most common global disturbances that maintain and promote many grassland ecosystems worldwide. The presence of non‐native, invasive plant species can alter fire ...regimes through changes in fuel properties that affect native vegetation in many ecosystems and are a leading threat to biodiversity and ecosystem function. Sericea lespedeza (Lespedeza cuneata), a non‐native, invasive forb frequently present in many North American tallgrass prairies, may reduce flammability by altering the fuel bed moisture and structural characteristics to reduce fire in this fire‐dependent ecosystem. The goal of this research was to examine the influence of sericea lespedeza on fuel bed structure, moisture, and flammability compared to native grassland fuels. Fuel bed burning trials, conducted in a controlled laboratory setting, tested for the effect of fuel load mass of native grass and sericea lespedeza litter, proportion of sericea fuel load, and fuel moisture content on flammability metrics. Regardless of moisture content, sericea lespedeza reduced flammability and reduced maximum fire temperatures by as much as 500°C. Sericea lespedeza poses a major threat to North American tallgrass prairies by decreasing flammability of fuel beds through increased fuel bed density and moisture retention.
Projections of future water shortages in the world's glaciated mountain ranges have grown increasingly dire. Although water modeling research has begun to examine changing environmental parameters, ...the inclusion of social scenarios has been very limited. Yet human water use and demand are vital for long-term adaptation, risk reduction, and resource allocation. Concerns about future water supplies are particularly pronounced on Peru's arid Pacific slope, where upstream glacier recession has been accompanied by rapid and water-intensive economic development. Models predict water shortages decades into the future, but conflicts have already arisen in Peru's Santa River watershed due to either real or perceived shortages. Modeled thresholds do not align well with historical realities and therefore suggest that a broader analysis of the combined natural and social drivers of change is needed to more effectively understand the hydrologic transformation taking place across the watershed. This article situates these new geographies of water and climate change in Peru within current global change research discussions to demonstrate how future coupled research models can inform broader scale questions of hydrologic change and water security across watersheds and regions. We provide a coupled historical analysis of glacier recession in the Cordillera Blanca, declining Santa River discharge, and alpine wetland contraction. We also examine various water withdrawal mechanisms, including smallholder agriculture, mining, potable water use, hydroelectric power generation, and coastal irrigation. We argue that both ecological change and societal forces will play vital roles in shaping the future of water resources and water governance in the region.
Quantifying groundwater flow at seepage faces is crucial because seepage faces influence the hydroecology and water budgets of watersheds, lakes, rivers and oceans, and because measuring groundwater ...fluxes directly in aquifers is extremely difficult. Seepage faces provide a direct and measurable groundwater flux but there is no existing method to quantitatively image groundwater processes at this boundary. Our objective is to determine the possibilities and limitations of thermal imagery in quantifying groundwater discharge from discrete seeps. We developed a conceptual model of temperature below discrete seeps, observed 20 seeps spectacularly exposed in three dimensions at an unused limestone quarry and conducted field experiments to examine the role of diurnal changes and rock face heterogeneity on thermal imagery. The conceptual model suggests that convective air‐water heat exchange driven by temperature differences is the dominant heat transfer mechanism. Thermal imagery is effective at locating and characterizing the flux of groundwater seeps. Areas of active groundwater flow and ice growth can be identified from thermal images in the winter, and seepage rates can be differentiated in the summer. However, the application of thermal imagery is limited by diverse factors including technical issues of image acquisition, diurnal changes in radiation and temperature, and rock face heterogeneity. Groundwater discharge rates could not be directly quantified from thermal imagery using our observations but our conceptual model and experiments suggest that thermal imagery could quantify groundwater discharge when there are large temperature differences, simple cliff faces, non‐freezing conditions, and no solar radiation.
Article impact Statement: Thermal imagery can locate seeps and differentiate seepage rates but direct seepage quantification is limited by diverse technical factors.
It is of prime importance to understand feedbacks due to the release of carbon (C) stored in permafrost soils (permafrost‐climate feedback) and direct impacts of climatic variations on permafrost ...dynamics therefore received considerable attention. However, indirect effects of global change, such as the variation in soil nutrient availability and grazing pressure, can alter soil and surface properties of the Arctic tundra, with the potential to modify soil heat transfers toward the permafrost and impact resilience of Arctic ecosystems.
We determined the potential of nutrient availability and grazing to alter soil energy balance using a 16‐year split‐plot experiment crossing fertilization at different doses of nitrogen (N) and phosphorus (P) with protection from goose grazing. Moss biomass and some determinants of the surface energy budget (leaf area index (LAI), dead vascular plant biomass and albedo) were quantified and active layer thaw depth repeatedly measured during three growing seasons. We measured soil physical properties and thermal conductivity and used a physical model to link topsoil organic accumulation processes to heat transfer.
Fertilization increased LAI and albedo, whereas grazing decreased dead vascular plant biomass and albedo. Fertilization increased organic accumulation at the top of the soil leading to drier and more porous topsoil, whereas grazing increased water content of topsoil. As a result, topsoil thermal conductivity was higher in grazed plots than in ungrazed ones. Including these properties into a simulation model, we showed that, after 16 years, nutrient addition tended to shallow the active layer whereas grazing deepened mean July active layer by 3.3 cm relative to ungrazed subplots. As a result of OM accumulation at the surface, fertilization increased permafrost vertical aggradation rate by almost an order of magnitude (up to 5 mm year−1 instead of 0.7 mm year−1), whereas grazing slowed down permafrost aggradation by reducing surface uprising and deepening thaw depth.
Synthesis. We demonstrated that long‐term grazing and N and P addition, through their impact on vegetation and soil properties have the potential to impact permafrost dynamics to the same extent as contemporary temperature increase in High Arctic polygonal wetlands.
Résumé
Afin de comprendre les rétroactions causées par la respiration du carbone (C) stocké dans le pergélisol (rétroaction pergélisol‐climat), les impacts directs du changement climatique sur la dynamique du pergélisol ont reçu une attention considérable. Toutefois, les effets indirects du changement climatique, telles que la disponibilité en nutriments du sol et la pression de broutement, peuvent altérer les propriétés du sol et de surface de la toundra Arctique, avec le potentiel de modifier les transferts de chaleur vers le pergélisol et d'impacter la résilience des écosystèmes Arctiques.
Nous avons déterminé l'effet potentiel d'une disponibilité accrue en nutriment et du broutement sur la balance énergétique du sol grâce à une expérimentation en tiroir croisant différents niveaux de fertilization en azote (N) et phosphore (P) à une protection contre le broutement durant 16 ans. La biomasse des plantes vasculaires et des mousses, ainsi que plusieurs déterminants du budget radiatif de surface ont été quantifiés (indice de surface foliaire (LAI), biomasse de plantes vasculaires mortes et albédo). La profondeur de la couche active a été mesurée à répétition durant trois saisons de croissance. Les propriétés physiques du sol et sa conductivité thermique ont été mesurées, et nous avons utilisé un modèle physique de simulation pour lier l'accumulation de matière organique en surface aux transferts de chaleur dans le sol.
L'indice de surface foliaire et l'albédo ont augmenté dans les traitements de fertilization, alors que le broutement a diminué la biomasse de plantes vasculaires mortes et l'albédo. La fertilization a causé l'ajout de nouveaux horizons organiques peu décomposés sous la surface du sol, menant à des conditions plus sèches et à un sol plus poreux. À l'inverse, le broutement a augmenté la teneur en eau du sol. En conséquence, la conductivité thermique du sol était plus élevée dans les sous‐parcelles broutées que dans celles non‐broutées. En incluant ces propriétés dans un modèle de simulation, nous avons montré que l'addition de nutriments a diminué la profondeur de la couche active, tandis que le broutement l'a approfondie de 3.3 cm en moyenne. En conséquence de la création de nouveaux horizons organiques en surface, la fertilization a augmenté le taux d'aggradation vertical du pergélisol par un ordre de grandeur (jusqu'à 5.5 mm an−1 au lieu de 0.7 mm an−1), tandis que le broutement a ralenti l'aggradation du pergélisol en limitant l'élévation de la surface et en approfondissant la couche active.
Synthèse. Nous avons montré que l'effet à long‐terme du broutement et de l'ajout de N et P influençait la dynamique du pergélisol dans la même mesure que les augmentations de températures contemporaines, et ce en impactant la végétation et les propriétés du sol dans les marais polygonaux du Haut‐Arctique.
We demonstrated that long‐term grazing and N and P addition, through their impact on vegetation and soil properties have the potential to impact permafrost dynamics to the same extent as contemporary temperature increase in High Arctic polygonal wetlands.
Snake fungal disease (SFD) is an emerging disease caused by the fungal pathogen,
Ophidiomyces ophiodiicola
. Clinical signs of SFD include dermal lesions, including regional and local edema, crusts, ...and ulcers. Snake fungal disease is widespread in the Eastern United States, yet there are limited data on how clinical signs of SFD compare with laboratory diagnostics. We compared two sampling methods for
O. ophiodiicola
, scale clip collection and swabbing, to evaluate whether collection method impacted the results of polymerase chain reaction (PCR). In addition, we evaluated the use of clinical signs to predict the presence of
O. ophiodiicola
across seasons, snake habitat affiliation (aquatic or terrestrial) and study sites. We found no significant difference in PCR results between sampling methods. Clinical signs were a strong predictor of
O. ophiodiicola
presence in spring and summer seasons. Snakes occupying terrestrial environments had a lower overall probability of testing positive for
O. ophiodiicola
compared to snakes occupying aquatic environments. Although our study indicates that both clinical signs of SFD and prevalence of
O. ophiodiicola
vary seasonally and based on habitat preferences of the host, our analysis suggests that clinical signs can serve as a reliable indicator of
O. ophiodiicola
presence, especially during spring and summer.
Spatially distributed surface temperature is an important, yet difficult to observe, variable for physical glacier melt models. We utilize ground‐based thermal infrared imagery to obtain spatially ...distributed surface temperature data for alpine glaciers. The infrared images are used to investigate thermal microscale processes at the glacier surface, such as the effect of surface cover type and the temperature gradient at the glacier margins on the glacier's temperature dynamics. Infrared images were collected at Cuchillacocha Glacier, Cordillera Blanca, Peru, on 23–25 June 2014. The infrared images were corrected based on ground truth points and local meteorological data. For the control points, the Pearson's correlation coefficient between infrared and station temperatures was 0.95. The ground‐based infrared camera has the potential for greatly improving glacier energy budget studies, and our research shows that it is critical to properly correct the thermal images to produce robust, quantifiable data.
Key Points
Ground based infrared images provide unprecedented glacier temperature data
Debris cover increases variability of glacier‐surface temperature
Heating from glacier's margin is an important energy flux
Hydrological responses to climate change are a widely concerning question, particularly for the source region of the Yellow River (SRYR), which is sensitive to climate change and is widely underlain ...by frozen ground. In considering climate change impacts on catchment properties, the traditional separation approach based on the Budyko framework was modified to identify and quantify the climatic causes of discharge changes. On the basis of the decomposition method, the traditional separation method and the modified separation method were used to analyse the discharge change in the SRYR. Using the observed annual maximum frozen depth (MFD) to indicate the frozen ground level, the impacts of frozen-ground degradation on the discharge change were further considered using the modified separation method. Our results show that the traditional separation approach underestimated climate-induced discharge change; over the past half-century, the discharge change in the SRYR has been primarily controlled by climate change. Increasing air temperature is generally a negative force on discharge generation; however, it also causes frozen ground to degrade—a positive factor for discharge generation. Such conflicting effects enhance the uncertainty in assessments of hydrological responses to climate change in the sub-basins with widely distributed permafrost.
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