Bryan G. Mark

Tropical glacier meltwater contribution to stream discharge: a case study in the Cordillera Blanca, Peru

Discharge measurements, climate observations and hydrochemical samples gathered monthly (1998/99) in the Yanamarey and Uruashraju glacier-fed catchments of the Cordillera Blanca, Peru, permit an analysis of the glacier meltwater contribution to stream-flow. These glacier catchments feed the Rio Santa, which discharges into the Pacific Ocean. Based on a water-balance computation, glacier melt contributes an estimated 35% of the average discharge from the catchments. For comparison, a volumetric end-member mixing model of oxygen isotopes shows glacier melt contributes 30-45% to the total annual discharge. Based on stream geochemistry, discharge from the Yanamarey glacier catchment provides 30% of the annual volume discharged from the Querococha watershed, which is < 10% glacierized. By analogy, the larger Rio Santa watershed, also < 10% glacierized, receives at least 12% of its annual discharge from melting glacier ice. Tributary watersheds to the Rio Santa with larger fractions of glacier cover have less variable runoff and enhanced discharge, demonstrating that the glaciers effectively buffer stream discharge seasonally. With continued glacier melting, stream-flow will likely become more variable, and there will be less dry-season runoff.

Climate Change and Tropical Andean Glacier Recession: Evaluating Hydrologic Changes and Livelihood Vulnerability in the Cordillera Blanca, Peru

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 (δ18O and δ2H) 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.

Glacier loss on Kilimanjaro continues unabated

The dramatic loss of Kilimanjaros ice cover has attracted global attention. The three remaining ice fields on the plateau and the slopes are both shrinking laterally and rapidly thinning. Summit ice cover (areal extent) decreased ≈1% per year from 1912 to 1953 and ≈2.5% per year from 1989 to 2007. Of the ice cover present in 1912, 85% has disappeared and 26% of that present in 2000 is now gone. From 2000 to 2007 thinning (surface lowering) at the summits of the Northern and Southern Ice Fields was ≈1.9 and ≈5.1 m, respectively, which based on ice thicknesses at the summit drill sites in 2000 represents a thinning of ≈3.6% and ≈24%, respectively. Furtwängler Glacier thinned ≈50% at the drill site between 2000 and 2009. Ice volume changes (2000–2007) calculated for two ice fields reveal that nearly equivalent ice volumes are now being lost to thinning and lateral shrinking. The relative importance of different climatological drivers remains an area of active inquiry, yet several points bear consideration. Kilimanjaros ice loss is contemporaneous with widespread glacier retreat in mid to low latitudes. The Northern Ice Field has persisted at least 11,700 years and survived a widespread drought ≈4,200 years ago that lasted ≈300 years. We present additional evidence that the combination of processes driving the current shrinking and thinning of Kilimanjaros ice fields is unique within an 11,700-year perspective. If current climatological conditions are sustained, the ice fields atop Kilimanjaro and on its flanks will likely disappear within several decades.

New Geographies of Water and Climate Change in Peru: Coupled Natural and Social Transformations in the Santa River Watershed

Projections of future water shortages in the worlds 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 Perus 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 Perus 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.

Hydrochemical evaluation of changing glacier meltwater contribution to stream discharge: Callejon de Huaylas, Peru / Evaluation hydrochimique de la contribution évolutive de la fonte glaciaire à l'écoulement fluvial: Callejon de Huaylas, Pérou

Abstract Discharge measurements, precipitation observations and hydrochemical samples from catchments of the Callejon de Huaylas watershed draining the Cordillera Blanca to the Rio Santa, Peru, facilitate estimating the glacier meltwater contribution to streamflow over different spatial scales using water balance and end-member mixing computations. A monthly water balance of the Yanamarey Glacier catchment shows elevated annual discharge over December 2001–July 2004 compared to 1998–1999, with net glacier mass loss in all months. Glacial melt now accounts for an estimated 58% of annual mean discharge, 23% greater than 1998–1999. At Lake Querococha, below Yanamarey (3.4% glacierized), a hydrochemical end-member mixing model estimates that 50% of the streamflow is derived from the glacier catchment. Average concentrations from the Rio Santa leaving the Callejon de Huaylas (8% glacierized) are modelled as a mixture with 66% deriving from glacierized tributaries of the Cordillera Blanca as opposed to the non-glacierized Cordillera Negra end member.

Accumulation at South Pole: Comparison of two 900‐year records

Two 900-year records of annual accumulation at South Pole are compared to evalu- ate the origin and significance of observed variations. Despite difficulties establishing absolute timescales, due to problems identifying annual layer markers, the two records can be correlated with confidence after moderate smoothing. This correlation shows that over the time period considered (1050-1956 A.D.) no climatically significant changes in accumulation occurred. In- stead, fluctuations preserved in the two cores reflect spatial variations in snow accumulation, as- sociated with nonuniform deposition induced by surface relief on the scale of several kilometers.

A review of methods for estimating the contribution of glacial meltwater to total watershed discharge

Glaciers store water over a range of temporal scales with important implications for downstream human and natural systems. Assessment of the contribution of glacial meltwater runoff to total watershed discharge is an essential part of climate change risk assessment and sustainable water management in glacierized watersheds. Over the past decade, a range of techniques for quantifying the proportional contribution of glacial meltwater has been presented in the scientific literature. Here we examine five different methodological approaches: direct discharge measurement, glaciological approaches, hydrological balance equations, hydrochemical tracers, and hydrological modeling. After a brief summary of the role of glaciers in watershed hydrology, we evaluate each approach, with regard to their respective data requirements, assumptions, and associated uncertainties. Next, we discuss factors that researchers must consider in deciding upon a particular methodological approach, then conclude with a discussion of future research needs. We underscore the need for expanded meteorological, hydrological, and glaciological monitoring networks in glacierized watersheds worldwide, for more comprehensive assessment of uncertainty and for better integration of research with the specific needs of watershed stakeholders.

Migration Amidst Climate Rigidity Traps: Resource Politics and Social-Ecological Possibilism in Honduras and Peru

According to dominant narratives about adaptation to climate change, those facing worst-case scenarios, without means at their disposal to adapt in situ, face an ineluctable set of adaptation strategies that ultimately includes the permanent abandonment of geographic spaces rendered uninhabitable and unproductive for human use. Yet environmental stress and adaptive capacity are distributed unevenly, and power structures play a role in fashioning them. It is argued here that when access to land and water are impacted by environmental stress, the structures that mediate their access are reinforced, even as the adaptive alternatives for smallholders are undermined. In this way, dominant resource regimes set up migration as the primary viable alternative for adaptation among a dwindling set of choices. This framework is applied to two early analogues of climate change impacts: flooded Garífuna villages of Hondurass North Coast and communities enduring glacier recession and shifting hydrologic regimes in Perus Cordillera Blanca. In both cases, stress motivates new forms of migration that reinforce dominant power structures. In Honduras, migrants from wealthier social strata are moving on a more permanent basis, and in Peru, the once historical pattern of labor migration is becoming a practical necessity. These cases underscore the role of political economy in adaptation to climate change and adaptive migration in particular.

Impacts of Glacier Recession and Declining Meltwater on Mountain Societies

Glacierized mountains are often referred to as our worlds water towers because glaciers both store water over time and regulate seasonal stream flow, releasing runoff during dry seasons when societies most need water. Ice loss thus has the potential to affect human societies in diverse ways, including irrigation, agriculture, hydropower, potable water, livelihoods, recreation, spirituality, and demography. Unfortunately, research focusing on the human impacts of glacier runoff variability in mountain regions remains limited, and studies often rely on assumptions rather than concrete evidence about the effects of shrinking glaciers on mountain hydrology and societies. This article provides a systematic review of international research on human impacts of glacier meltwater variability in mountain ranges worldwide, including the Andes, Alps, greater Himalayan region, Cascades, and Alaska. It identifies four main areas of existing research: (1) socioeconomic impacts; (2) hydropower; (3) agriculture, irrigation, and food security; and (4) cultural impacts. The article also suggests paths forward for social sciences, humanities, and natural sciences research that could more accurately detect and attribute glacier runoff and human impacts, grapple with complex and intersecting spatial and temporal scales, and implement transdisciplinary research approaches to study glacier runoff. The objective is ultimately to redefine and reorient the glacier-water problem around human societies rather than simply around ice and climate. By systematically evaluating human impacts in different mountain regions, the article strives to stimulate cross-regional thinking and inspire new studies on glaciers, hydrology, risk, adaptation, and human–environment interactions in mountain regions.

Measuring glacier surface temperatures with ground-based thermal infrared imaging

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 glaciers 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 Pearsons 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.