Mountain ice, water and climate along the Andean Southern Volcanic Zone: A decade (and counting!) unfolding a unique landscape

Stretching from ~33ºS to ~46ºS, the Southern Volcanic Zone (SVZ) in the Andes constitutes one the most continuous glaciated volcanic regions along the midlatitudes. Here, most headwaters are on active volcanoes, with glaciers in a notable variety of forms, including valley glaciers, ice aprons, mountain glaciers, and crater glaciers. Furthermore, ubiquitous glacial landforms attest for larger ice coverage in the past. Building from earlier foundational case studies, since 2015 we have developed a multidisciplinary and multiscale research program focusing on the glacierized SVZ landscape including, but not limited to, past, present, and future climate patterns, geomorphology, glacier changes, and mountain (socio)hydrology. Here, we summarize this research endeavor and present the main findings to date, aiming to integrate our case studies into a cohesive regional perspective. Individual efforts of several research groups working across different sections of the SVZ have converged towards a more cohesive program under years of networking, funding acquisition, and mentoring of students and early career researchers. Together, we have applied a diverse range of methods to study the components of the glacial SVZ landscape, including instrumental hydroclimatic observations, numerical modeling, geomorphological mapping, radionuclide and optically stimulated luminescence dating, geodetic measurements, remote sensing processing, and geospatial techniques. Analysis of instrumental observations and high-resolution climate modeling indicates North-South and East-West temperature and precipitation contrasts associated with uniquely complex topographic dynamics. Geomorphology analysis reveals that current topographic complexity has been shaped by a mixture of Pleistocene to Holocene volcanism, reverse faulting along the western Andean front and transpressive faulting along the intrarc, and long-term glacier erosion. These processes possibly explain remarkable patterns of glacier sensitivity to climate change, as extensive glacier accumulation zones develop along the northern (33ºS to 36°S) and southern (42ºS to 46°S) sections, unlike intermediate SVZ latitudes where mountaintops rarely rise above the free-atmosphere freezing level height. Dating of moraines preserved around some SVZ glaciers points to several Holocene regional advances since ~4000 years BP, although some anomalously high and steep moraine complexes, glacio-volcanic landforms, as well as significant differences in glacier size across short distances, point to potentially non-climatic forcings that remain poorly understood. Remote sensing and glaciological mass balance, coupled with model simulations, predict uninterrupted clean ice losses during the 21st century, even under the most optimistic climate warming mitigation scenarios. The dynamics of debris-covered areas, however, remain insufficiently quantified. Studies using water isotopes from a partially glacierized catchment located at 38.9ºS, reveal diverse mountain hydrology, where groundwater and ponds are key contributors to streamflow. However, glacier melt seems disproportionately important relative to the ice surface coverage. In this presentation, we aim to demonstrate how these case studies point to interlinked dynamics that have not been traditionally studied in the mountain sciences, impacting interpretations of long-term glacier changes and their hydrological consequences. Finally, we outline challenges and opportunities ahead, including new research priorities to advance interdisciplinary characterization of the glaciated SVZ. This work highlights the potential of converging diverse research agendas towards a common goal of unveiling interactions among mountain ice, water and climate.