Los Glaciares National Park

The main non-native mammal species within the site include populations of cattle (Bos taurus) and feral equines (Equus caballus), European hare (Lepus europaeus) and American mink (Neovison vison). Invasive American mink is a severe threat to endangered waterbird populations, such as the torrent duck (Merganetta armata). Mink has a proven acute impact on the Hooded Grebe (Podiceps gallardoi), a critically endangered specialist of highland plateau lakes in Patagonia where a single mink attack can deplete up to 4% of the global population (Fasola and Roesler, 2018). Likewise, the invasions of exotic fish represent a significant loss of biodiversity for the site. Native species are completely excluded from some sectors (Testoni, 2018). In the Santa Cruz river basin, whose headwaters are located within the site, four exotic salmonids species have been registered: chinook salmon (Oncorhynchus tshawytscha), rainbow trout (Oncorhynchus mykiss), lake trout (Salvelinus namaycush) and brown trout (Psalm trutta). The presence of the diatom algae (Didimosphenia geminata) in some water bodies represents the main conservation problem of these environments, mainly affecting their quality (Testoni, 2018). Invasions caused by exotic plants, such as Rosa rubiginosa, constitute one of the most relevant conservation problems of the site. The presence of domestic dogs that roam without the control of their owners is a problem of particular concern in the Northern Zone, especially in the areas where the huemul is present (Administración de Parques Nacionales, 2019). Although invasive species pose a high threat to the important biodiversity values of the site, they do not impact the natural beauty and geomorphic processes for which the site was inscribed.

There is an important seasonality factor in the tourism of Los Glaciares National Park - the high season occurs between September and April. Between September 2022 and April 2023, there were 781,823 registered entrances to the National Park (Secretaria de Turismo de El Calafate, 2023), compared to less than 80,000 in the early 1990s (UNEP-WCMC, 2011). This is considering that the northern area of the Park lacks data since no registration was required to enter the Park in El Chaltén until 2024. Negative impacts derived from tourism have been detected in the site in recent years, such as the increasing use by tourists and residents of spontaneous trails, progressive damage to soil and vegetation, pollution of water courses caused by inadequate local infrastructure such as the El Chaltén overloaded waste-water plant (condemned in September 2024 by Camara Federal De Comodoro Rivadavia), and excessive use of some areas, such as the Perito Moreno Glacier area (Administración de Parques Nacionales, 2019).

Climate change is causing the majority of the glaciers in the National Park to recede significantly. According to available climatic models, a significant change in regional average temperatures and precipitation patterns could lead to important changes in river dynamics (Villalba et al., 2017). Annual average temperature increase (especially in the summer) has had an effect on the position of the regional snow line, forcing its elevation. This has caused a general retreat of most of the Patagonian glaciers (Administración de Parques Nacionales, 2019). In 2015, the Viedma glacier showed the highest retreat rates over the last 40 years (Lo Vecchio et al., 2018).

Even for optimistic scenarios of drastic greenhouse gas emission reductions (low-emission scenarios, such as RCP2.6), projections show that tropical glaciers are likely to lose between 30-98% of their ice by 2100, while glaciers in the rest of the southern Andes would also experience significant losses (~8-35%). If emissions continue to increase under a less optimistic climate scenario (RCP8.5), glacier ice loss will increase, projected to reach between ~70-100% and ~30-58% for the low-latitude and southern Andes, respectively. Preserving many low-latitude glaciers is likely to be an insurmountable challenge: recent projections of a +2°C warming scenario show that this region of the Andes will be completely, or almost completely, ice-free by 2100. Such ice loss in the Andes will increase stress on freshwater resources on which communities and major cities in the lower reaches of the watersheds depend, especially during periods of drought (Davies et al., 2025). Projections of glacier evolution in Los Glaciares National Park illustrate the slow response time of large glaciers. The low accumulation area ratio (AAR) values (50%) modelled for the glaciers in this site at the end of the 21st century indicate a strong imbalance between the remaining large ice volume and climatic conditions and thus the continuation of ice loss beyond 2100 (Bosson et al., 2019). If the green house gas emissions remain similar to the current rate (2.6%), in the year 2100 there would be a reduction in the volume of glaciers in the National Park of between 20-40% (Administración de Parques Nacionales, 2019). On the other hand, events of heavy rainfalls, combined with deglaciation could provoke a Glacial Lake Outburst Flood (GLOF). The vulnerability of the region is assessed by SEGEMAR. Main processes active in the area correspond to rockfalls, landslides, fluvial erosion and, to a lesser extent, flooding erosion and overflowing of rivers. Massive landslide phenomena are widely distributed in the studied area due to the high relative relief available and to the weathering processes linked to glacial activity (Balbi et al., 2019).

Higher summer temperatures coinciding with decreasing precipitation increases the vulnerability of native steppes and forests to wildfires (World Heritage Committee, 2014). For northern Patagonia in Argentina, studies show a 0.53°C increase in annual temperature during the 20th century (Villalba et al., 2005) and a decrease in mean annual precipitation (Masiokas et al., 2008). These changes have led to direct impacts on forest ecosystems, such as reduced growth and tree mortality (Amoroso et al., 2015; Rodríguez-Catón et al., 2016; Suarez et al., 2004; Villalba and Veblen, 1998). Future projections of climate change in the region, based on the HasCM3 model, predict that temperatures will continue to increase at the same rate as in the last 60 years and that precipitation will decrease by about 30% in the Andes (Centro de Investigaciones del Mar y la Atmósfera, 2014). Nothofagus trees are negatively affected by prolonged high temperatures and will increase with climate change (Bonada et al., 2022). The decrease in precipitation in recent decades has influenced the number of fires in drier years and the size of fires, which increased along the northwest-southeast gradient of decreasing precipitation (Bianchi et al., 2023). Fire regimes are largely human-driven, and conditioned by climate and landscape characteristics.

Cattle and sheep grazing have been modifying the native steppes and forests long before the World Heritage inscription (State Party of Argentina, 1981) with impacts on native flora, fauna and habitat quality. Perilake and wet-meadows (mallines) are disturbed by trampling and grazing, leading to loss of vegetation cover and soil, water pollution and affecting water retention capacity. This in turn favours exotic species establishment and affects species that use those ecosystems, such as nesting birds like Rallus antarticus (Administración de Parques Nacionales, 2019; Testoni, 2018). While some areas have since been naturally recovering, pressure continues to exist, including in some areas from feral cattle (World Heritage Committee, 2014). Feral cattle is considered one of the most serious conservation problems, as it affects 20% of the World Heritage site (Administración de Parques Nacionales, 2019; Testoni, 2018). The threat is ranked as high due to the potential effects on the exceptional natural beauty and on the other important biodiversity values of the site.

Historically, there has been intense hunting of puma (Puma concolor), fox (Lycalopex culpaeus, L. griseus) and guanaco (Lama guanicoe). Ranches continue to operate in the surroundings of the site and both retaliation killings of predators and poaching of guanaco have been reported (IUCN, 2014). Hunting of huemul (Hippocamelus bisulcus) from the roads and trails is circumstantial, specially in the area of influence of Provincial Route No. 41, both within the protected area and beyond its northern boundary (Administración de Parques Nacionales, 2019). This is a low threat from a World Heritage perspective due to the focus on landscape beauty and geological values.

The wastewater treatment plant in the village of El Chaltén is inadequate for both the 2,000 residents and the approximately 10,000 visitors it hosts annually. Between 2021 and 2023, results from a participatory research project showed the presence of faecal bacteria and the development of antibiotic-resistant bacteria (Crosa, 2022; Dominguez, 2023). Additionally, the plant's toxic waste is stored at an unlined landfill, located near the Viedma Lake area. In November 2023, an emergency environmental lawsuit was filed by local residents (Martin, EXPTE. N° FCR - 16722/2023). As part of the lawsuit, the provincial judge acknowledged the importance of preserving rivers, especially in World Heritage sites, and ordered the expansion of the treatment plant and remediation of contamination. There are also significant uncertainties about the extent of contamination due to the lack of adequate faecal waste treatment infrastructure in the camping areas and along the trails in the northern zone of Los Glaciares National Park. No information exists regarding the impact of the lack of treatment on groundwater and soils. Progress is partly dependent on inter-institutional coordination and funding for the necessary works (Anière, 2024). While overall, the pollution presents a high threat to the freshwater reservoir, it does not present a high threat on the key attributes of the World Heritage values.

Even though infrastructure expansion has mostly been occurring outside the World Heritage site, the visual impacts are striking nonetheless (UNEP-WCMC, 2011). There is a mismatch between tourism growth and corresponding planning and management (Auditoría General de la Nación, 2015; Despouy, 2015; Administración de Parques Nacionales, 2019).

Furthermore, real estate development in the contiguous national reserve, which serves as a de facto buffer zone, is an increasing risk due to the tourism boom and demand for secondary homes in Patagonia. In addition to conversion of habitat and disturbance (BirdLife International, 2017), it could cause important visual impacts. El Chaltén municipality is requesting the degazettement of 200 hectares of the World Heritage site in order to extend the urban area. This would ultimately lead to the downsizing of the protected area. Civil society organizations submitted a note to Santa Cruz Provincial Government, requesting the withdrawal of the initiative. In 2021 National Park’s authorities agreed on the cession of some 11 hectares in the northern part of the protected area, which will be destined to the expansion of the urban area of the town of El Chaltén; through a new sector of land for the installation of infrastructure and equipment for tourist and institutional activities in the town (Parques Nacionales, Noticias, 2021). Local organizations expressed their concern regarding potential environmental impacts of urban encroachment, such as soil erosion, spontaneous opening of new trails; inadequate waste and waste-water management and non-authorized wood extraction (ACEN, 2020). The threat is ranked as high, as it would potentially impact on the beauty of the overall landscape as well on other important biodiversity values. The evolution of the urbanized area is visible through satellite views of El Chaltén between 2014 and 2024 (World Imagery ESRI Wayback 2024-09-19 / 2014-02-20).