When another one bites the dust: Environmental impact of global copper demand on local communities in the Atacama mining hotspot as registered by tree rings.

Assessing the impact of mining activity on the availability of environmental pollutants is crucial for informing health policies in anticipation of future production scenarios of critical minerals essential for the transition to a net-zero carbon society. However, temporal and spatial monitoring is often sparse, and measurements may not extend far enough back in time. In this study, we utilize variations of chemical elements contained in tree-rings collected in local villages from an area heavily affected by copper mining in the Atacama Desert since the early 20th century to evaluate the temporal distribution of pollutants and their relationship with local drivers. By combining time-varying data on local drivers, such as copper production and the dry tailings deposit area, we show how the surge in copper production during the 1990s, fueled by trade liberalization and increased international demand, led to a significant increment in the availability of metal(loid)s related to mining activities on indigenous lands. Our findings suggest that the environmental legislation in Chile may be underestimating the environmental impact of tailing dams in neighboring populations, affecting the well-being of Indigenous Peoples from the Atacama mining hotspot region. We argue that future changes in production rates driven by international demand could have negative repercussions on the environment and local communities. Therefore, mining emissions and the management of tailing dams should be carefully considered to anticipate their potential negative effects on human and ecosystem health.

Heterogeneity in glacier thinning and slowdown of ice movement in the Garhwal Himalaya, India.

Limited ground-based surveys and extensive remote sensing analyses have confirmed glacier thinning in the Garhwal Himalaya. More detailed studies on specific glaciers and the drivers of reported changes are essential to comprehend small-scale differences in the effects of climatic warming on Himalayan glaciers. We computed elevation changes and surface flow distribution for 205 (≥0.1 km2) glaciers in the Alaknanda, Bhagirathi, and Mandakini basins, all located in the Garhwal Himalaya, India. This study also investigates a detailed integrated analysis of elevation changes and surface flow velocities for 23 glaciers with varying characteristics to understand the impact of ice thickness loss on overall glacier dynamics. We observed significant heterogeneity in glacier thinning and surface flow velocity patterns using temporal DEMs and optical satellite images with ground-based verification. The average thinning rate was found to be 0.07 ± 0.09 m a-1 from 2000 to 2015, and it increased to 0.31 ± 0.19 m a-1 from 2015 to 2020, with pronounced differences between individual glaciers. Between 2000 and 2015, Gangotri Glacier thinned nearly twice as much as the neighbouring Chorabari and Companion glaciers, which have thicker supraglacial debris that protects the beneath ice from melting. The transitional zone between debris-covered and clean ice glaciers showed substantial flow during the observation period. However, the lower reaches of their debris-covered terminus areas are almost stagnant. These glaciers experienced a significant slowdown (~25 %) between 1993-1994 and 2020-2021, and only the Gangotri Glacier was active even in its terminus region during most observational periods. The decreasing surface gradient reduces the driving stress and causes slow-down surface flow velocities and an increase in stagnant ice. Surface lowering of these glaciers may have substantial long-term impacts on downstream communities and lowland populations, including more frequent cryospheric hazards, which may threaten future water and livelihood security.

Using an unmanned aerial system to analyse environmental impacts of charcoal production on tropical savanna ecosystems in northwestern Kenya.

In many regions of Sub-Saharan Africa, charcoal plays an important role as energy source but is widely perceived as a major driver of deforestation and forest degradation. This narrative, however, is mostly based on research within primary production regions. Though space-borne remote sensing applications can be useful in monitoring such large-scale production modes, environmental effects of household-level production are less easy to assess. Therefore, the present study employs an unmanned aerial system (UAS) to assess the impact of small-scale charcoal production on the vegetation density in the immediate vicinity of production sites. The UAS data was complemented by field measurements and very high-resolution WordView-2 satellite imagery. This approach revealed only small differences between charcoal production sites and reference plots which were usually evened out after 20-25-m distance to the plot centre using a concentric ring analysis. Results further show that a distinction between different land-use practices is difficult, even with the high spatial resolution provided by a UAS. Thus, more research and new approaches are needed to evaluate the role of small-scale charcoal production in deforestation and forest degradation processes against the background of other human activities. However, to exploit the full potential of UAS for monitoring environmental effects in charcoal producing areas, official regulations need to be clearer and more reliable.

Assessing glacier changes in the Nanga Parbat region using a multitemporal photographic dataset.

This article presents a multitemporal photographic dataset from the Rupal Valley, south of Nanga Parbat in the north-western Himalaya. The historical metric photographs were taken in 1934, 1958 and 1987 during scientific expeditions focussing on topographical mapping and glacier dynamics of the mountain massif. All photographs showing glacier aspects have been collected from archives and repeated from the same viewpoints during several surveys between 1992 and 2010. This dataset allows for a detailed visual assessment of glacier fluctuations, changes in snout positions, ice volumes, and debris cover over almost eighty years. It offers insights for a better understanding of glacier changes in this prominent Himalayan mountain region. The dataset supports a recently published article (Nüsser and Schmidt, 2021) with original archival material.

Glacier changes on the Nanga Parbat 1856-2020: A multi-source retrospective analysis.

Contemporary changes in the Himalayan cryosphere are an important concern in the global climate change debate. In this context, the glaciers of the Upper Indus Basin (UIB) deserve special attention because of their importance for freshwater supply in the mountain valleys and the adjoining lowlands. However, detailed long-term glacier monitoring studies are rare due to the lack of historical data with adequate spatial and temporal resolution. In the case of Nanga Parbat, the ample availability of historical maps and terrestrial photographs together with satellite imagery and digital elevation models make it possible to analyse and quantify glacier changes for the period between 1856 and 2020. Using diverse multi-temporal datasets, this study reveals slight changes in ice-covered area for 63 glaciers, which decreased by 7% between 1934 and 2019. A detailed analysis of five glaciers in the Rupal Valley over the period 1856-2020 identifies diverse response patterns and highlights the importance of ice and snow avalanches, surge-type instabilities and site-specific topographic particularities for individual glacier changes. The results show high similarity with the stable glacier mass in the Karakoram. This study demonstrates the advantages of combining multiple sources and types of data in order to achieve consilience and offer robust insights.

Distribution and relevance of aufeis (icing) in the Upper Indus Basin.

In the semi-arid high mountains of the Upper Indus Basin (UIB), meltwater supply from the cryosphere is vital for irrigated agriculture and hydropower generation. An overlooked cryosphere component that is critical for this is aufeis, which appears as a sheet-like formation of ice layers, created by successive and laminated freezing of flowing water. This study aims to redress the lack of knowledge about this phenomenon by creating an inventory of aufeis fields for the UIB and analysing their spatial distribution, including the role of topographical parameters such as altitude, slope, and aspect. The study is based on a time-series analysis using Landsat imagery from 2010 to 2020, supported and validated by several field campaigns carried out between 2014 and 2020. In total, more than 3700 aufeis fields were detected covering an area of about 298 ± 38 km2. The spatial distribution of their occurrence indicates a distinct elevation range between 4000 and 5500 m a.s.l. and is marked by a pronounced longitudinal increase to the east. In contrast to the western part of the UIB (Gilgit-Baltistan), where only some few and small aufeis fields can be detected, 65% of the aufeis covered areas (195 ± 23 km2) exist on the Tibetan Plateau. Our database fills an important research gap and will help in further cryosphere studies in the UIB and beyond.

Recession of Gya Glacier and the 2014 glacial lake outburst flood in the Trans-Himalayan region of Ladakh, India.

This study assessed spatiotemporal changes at Gya Glacier, the associated development of a proglacial lake, and reconstructed the 2014 outburst flood that struck Gya Village in the Trans-Himalayan region of Ladakh, India. This study analyzed and for the first time modeled a Glacial Lake Outburst Flood (GLOF) event in the Trans-Himalayan region of Ladakh. Glacier and glacial lakes changes were quantified using remote sensing data supplemented with field observations. Glacier ice-thickness and glacier-bed overdeepenings were modeled using a shear-stress based model, GlabTop (Glacier-bed Topography). The reconstruction of the 2014 GLOF and the potential hazard assessment of Gya Lake were carried out using the hydrodynamic model HEC-RAS; results were validated against ground-collected data. Temporal evaluation of satellite data revealed a 45.6% loss in the total glacier area between 1969 and 2019. The earliest snow-free image available for the region shows that a proglacial lake existed as early as 1969 with an area of 3.06 ha. The lake has expanded to ~11 ha in 2019. Results from the GlabTop model suggest that the lake could grow further up to 12 ha in the future. Field-based geomorphic indicators suggest that the 2014 GLOF event resulted from a piping failure of the frontal moraine destroying numerous agricultural fields, some buildings, downstream infrastructure, and eroded natural channel embankments. The reconstruction of the event revealed that 25% of the lake waters drained out with a peak discharge of 470 m3s-1, inundating an area of ~4 km2 around Gya Village. However, a complete breaching of the terminal moraine could result in an event that would be 5.5 times larger than the 2014 GLOF. Therefore, this study could be useful not only in planning disaster-resilient infrastructure around proglacial lake environments in the cold-arid Ladakh but also in framing mitigation plans to reduce risk for vulnerable downstream communities.

Hydrochemical and environmental isotope analysis of groundwater and surface water in a dry mountain region in Northern Chile.

This case study examines the geological imprint and land use practices on water quality in the arid Huasco Valley against the backdrop of ongoing water conflicts surrounding competing demands for agriculture and mining. The study is based on a detailed analysis of spatial and temporal variations of monthly surface and bi-monthly groundwater quality samples measured during the Chilean summer of 2015/16. Additional information on source regions and river-groundwater interactions were collected using stable water isotopes. Regarding the geological impact on water quality, high concentrations of Ca2+, SO42- and HCO3- indicate a strong influence of magmatic rocks, which constitute this high mountain basin, on the hydrochemistry. Piper and Gibbs-diagrams revealed that all samples show a homogenous distribution dominated by rock-water interactions. Measured NO3- concentrations in surface water are generally low. However, groundwater aquifers exhibit higher concentrations. Mn is the only heavy metal with elevated concentrations in surface water, which are possibly related to mining activities. The results illustrate that both surface and groundwater can be classified as suitable for irrigation. In addition, groundwater has been found to be suitable as drinking water. High similarities in isotopic signatures indicate a strong connection between surface and groundwater. Isotopic analyses suggest a strong influence of evaporation. This combined approach of hydrogeochemical and isotopic analysis proved to be a helpful tool in characterizing the catchment and can serve as a basis for future sustainable water management.