103. Sanford (2011) Glacial changes between 1985-2009 and implications for volcanic hazards at Mt. Rainier, Washington
     Glaciers throughout the world have shown decreases in size in recent years (WGMS, 2008). Because of their sensitivity to temperature and precipitation changes, glaciers are good indicators for climate change (Nylen, 2001). Glaciers located in temperate areas are especially sensitive to warming due to their relatively quick flow and high mass turnover (WGMS, 2008). In areas with significant amounts of glaciation, a warmer climate can have a considerable effect. A ~0.6°C increase in the mean global temperature is responsible for the overall retreat of mountain glaciers since the early 20th century (Hock et al., 2005). Further decreases are expected due to increased global warming as predicted by General Circulation Models (Hock et al., 2005). Several potentially active volcanoes with rapidly thinning glaciers are located in Mexico, Columbia, Chile, and Tanzania (Tuffen, 2010). Tuffen (2010) estimates that if the current rate of thinning continues glaciated volcanoes would lose a large portion of ice. At Popocatépetl in Mexico, this has already happened. The amount of ice on Popocatépetl decreased 53% from 1996-2001, which was partially due to eruptive activity (Julio-Miranda et al., 2008). Other mountain glaciers around the world have also experienced decreases in areal extent. The World Glacier Monitoring Service (WGMS) reports that annual melting rates of mountain glaciers have doubled since the turn of the century (WGMS, 2008). New records for ice loss were also set in 2003, 2004, and 2006 (WGMS, 2008). Significant glacier changes could affect local hazards due to the decrease in glacial coverage and the increase in melt water. Glaciers, ice caps, and ice sheets cover approximately 10% of Earth‟s surface and contain 75% of its freshwater (UNEP, 1992; Nylen, 2001). Hazards in volcanic regions that could occur as a result of melting glaciers include lahars, debris/ice avalanches, eruptions, and jökulhlaups (glacier outburst floods) (Hoblitt et al., 1998). Recent changes in glacial extent on Mt. Rainier could increase hazard risks due to the increase in melt water and steep exposed slopes (Crandell, 1971). The large amounts of loose debris, along with slopes that have been weakened as a result of hydrothermal alteration, also increase hazard risks at Mt. Rainier (Reid et al., 2001). The amount and rate at which Mt. Rainier glaciers are retreating is important for determining risks from hazards such as lahars, debris avalanches, eruptions, and jökulhlaups. Remote sensing provides an alternative method of monitoring glaciers changes as opposed to ground surveys or aerial photographic surveys. Glacier mapping using satellite images is generally less expensive and involves a smaller amount of labor than ground and aerial surveys (Sidjak and Wheate, 1999). Many studies have used Landsat images to map and interpret glacier changes around the world in places such as Iceland, British Columbia, Austria, and Peru (Williams et al., 1997; Sidjak and Wheate, 1999; Paul, 2002; Silverio and Jaquet, 2005). They show that satellite images are useful for collecting data on glacier extent, which can then be used for water management and climate monitoring purposes (Sidjak and Wheate, 1999). They are especially useful in places like the Tibetan Plateau, where areas with rugged terrain and lack of access make ground surveys very difficult or impossible (Zhen et al., 1998). This study concentrates on the changes in glacier areal extent that have occurred at Mt. Rainier and some of the possible consequences of those changes in terms of volcanic hazards. The first objective of this study is to measure the changes in glacier area from 1985-2009 at Mt. Rainier with satellite images. This study maps the areal extents of glaciers and groups of glaciers on Mt. Rainier as a function of time and then examines the rate of ice loss or gain for each glacier/glacier group as well as the rate of total ice loss or gain. These measurements are compared with measurements made by the United States Geological Survey (USGS) and the Global Land Ice Measurements from Space (GLIMS) project. The second objective is to determine the possibility of an increased risk for eruptions at Mt. Rainier due to the removal of glaciers from its slopes. This study examines the relationship between glacier change and eruption rates in the past by comparing the modeled glacier area at Mt. Rainier for the last 10 ka to the eruptive history of Mt. Rainier and other Cascade volcanoes during the same period. Any correlations between times of deglaciation and increases in eruption rates could help in predicting future volcanic activity resulting from continued glacial retreat at Mt. Rainier.
552. Hotaling et al. (2022) Summer dynamics of microbial diversity on a mountain glacier
     Glaciers are rapidly receding under climate change. A melting cryosphere will dramatically alter global sea levels, carbon cycling, and water resource availability. Glaciers host rich biotic communities that are dominated by microbial diversity, and this biodiversity can impact surface albedo, thereby driving a feedback loop between biodiversity and cryosphere melt. However, the microbial diversity of glacier ecosystems remains largely unknown outside of major ice sheets, particularly from a temporal perspective. Here, we characterized temporal dynamics of bacteria, eukaryotes, and algae on the Paradise Glacier, Mount Rainier, USA, over nine time points spanning the summer melt season. During our study, the glacier surface steadily darkened as seasonal snow melted and darkening agents accumulated until new snow fell in late September. From a community-wide perspective, the bacterial community remained generally constant while eukaryotes and algae exhibited temporal progression and community turnover. Patterns of individual taxonomic groups, however, were highly stochastic. We found little support for our a priori prediction that autotroph abundance would peak before heterotrophs. Notably, two different trends in snow algae emerged—an abundant early- and late-season operational taxonomic unit (OTU) with a different midsummer OTU that peaked in August. Overall, our results highlight the need for temporal sampling to clarify microbial diversity on glaciers and that caution should be exercised when interpreting results from single or few time points.
551. Kincaid (2024) Using historic glacial data and GIS to predict Mount Rainier National Park's glacial future
     Will Washington state have glaciers 100 years from now (year 2124)? Due to generally warmer weather glaciers are largely in retreat globally, including the glaciers in Washington state. In Washington state summer glacial meltwater plays a vital role in the survival of wildlife and is needed for human purposes that include recreation, power generation, drinking, agricultural, and industrial. This project looked at the most resilient glaciers in Washington state, the glaciers at Mount Rainier National Park. Historic measurements were used in an exponential growth calculation to project the amount in acres each glacier at Mount Rainer will advance or retreat over the next 100 years. The glaciers were digitized into ArcGIS Pro and then adjusted according to the calculations. The results of the project show that all the glaciers at Mount Rainier should be intact in 2124. This is of vital importance to wildlife and human populations that depend on the summer meltwater for various purposes.
550. Florea et al. (2022) Fumarole-ice dynamics in cryo-speleology on volcanic edifices—Mount Rainier, Washington, USA
     The persistent fumarole ice caves nearly circumnavigating the East Crater of Mount Rainier in the Cascade Volcanic Arc in Washington, USA, are a natural laboratory to study the dynamic equilibrium between thermal flux and glacial ice. The large circum‐crater passage connects to entrances on the crater rim by steep transverse passages, and fumarole gas convection and advection maintains the cave passage distribution and morphology. Between August 2016 and August 2017, we collected hourly data using remote sondes that include temperatures at three fumarole, cave air temperature and pressure, water temperature and depth in an in‐cave meltwater lake, and the outside temperature and snow depth at Paradise Visitors Center. Correlation and wavelet analyses of these data reveal complex associations between patterns of weather, fumarole activity, and lake level. At longer scales, fumarole temperatures behave largely independently and connected to spatial and temporal changes in volcanic heat flux and glacial melt circulation. At the scale of individual storm‐events, major snowfalls seal the cave entrances, increasing cave air temperature and pressure from fumarole output and causing rising lake levels from increased melt until entrances reopen. Repeating freeze‐thaw cycles observed in the cave monitoring data are a primary cause of crater mass‐wasting.
549. Stenner et al. (2023) Morphodynamics of glaciovolcanic caves—Mount Rainier, Washington, USA
     The twin summit craters of Mount Rainier, Washington, USA host the largest known glaciovolcanic caves in the world and at 4382 m, the highest elevation caves in the USA. The caves are formed in ice at the glacier-rock interface by volcanogenic gases and atmospheric advection. However, the way in which discrete caves are formed and evolve remains poorly understood. Surveys of the cave systems in 1970−1973 and 1997−1998 in both the West and East Craters documented cave passage morphology. Field expeditions from 2014−2017 comprehensively surveyed the Rainier summit caves and undertook thermal imaging and temperature monitoring. Significant changes had occurred. In the East Crater, documented cave length has nearly doubled since 1973 to 3593 m of passage spanning 144 m of depth, revealing a new subglacial lake, and now nearly circumnavigating the East Crater. Of the reported increase in length, some 600 m of the mapped passage is possibly newly formed. Across 47 years of observation, certain sections of the cave appear to be preserved in form and position through time, while others are more actively being lost or forming. Conserved passages are generally sub-horizontal, passages following the curvilinear crater contours, show low temperature variability, and are dependent on perennial fumarolic activity or distributed heat flux emanating from warm bedrock and sediment floors. Transient passages are smaller diameter dendritic passages following the slope of the ice-rock interface towards entrance zones and normal to the circum-crater passage. They also show higher variability in temperature and airflow and are subject to seasonal weather and mechanical collapse, which may contribute to transience. Additional research is required to confirm the mechanisms maintaining conserved passages and formation of transient passages.
548. Vaux et al. (2026) Dissolved black carbon in North Cascades snow, meltwater, and a downstream river
     Quantification of black carbon on snow in the Cascade Range is needed due to increasing wildfire intensity and frequency. Here, the benzenepolycarboxylic acid (BPCA) molecular method was used to measure dissolved black carbon (DBC) in snow, nearby rivers, streams, and supraglacial melt collected in 2022 and 2023 from Mount Baker and Mount Rainier. The average DBC concentration in snow was 9 ± 4 μg-C/L and 10 ± 6 μg-C/L in stream, river, and supraglacial meltwater samples. The DBC method provides black carbon source identification via BPCA characterization. DBC concentrations and BPCA proportions were compared to modeled smoke deposition from the Navy Aerosol Analysis and Prediction System reanalysis model. In both years, total deposition from May through October was approximately 670 mg/m2. However, early season smoke deposition (May through July) was four times higher in 2023 than 2022, indicating seasonal variability in the timing of deposition. Dry deposition accounted for over 80 percent of total late season smoke deposition (August through October) in both 2022 and 2023, while wet deposition accounted for 75 and 30 percent of total early season deposition in 2022 and 2023, respectively. The largest smoke deposition events on Mount Baker coincided with precipitation events and enrichment of benzenepentacarboxylic acid, a marker of biomass burning, in snow. Using the Snow, Ice, and Aerosol Radiative model, we estimated an average albedo of 0.68 ± 0.03. The resulting instantaneous radiative forcing attributable to the presence of BC in snow ranged from 3 to 16 W/m2, with an average of 7.47 ± 3.3 W/m2.

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The U.S. Geological Survey Cascades Volcano Observatory and the University of Washington Pacific Northwest Seismic Network continue to monitor Washington and Oregon volcanoes closely and will issue additional notifications as warranted.

Website Resources

For images, graphics, and general information on Cascade Range volcanoes: https://www.usgs.gov/observatories/cvo
For seismic information on Oregon and Washington volcanoes: http://www.pnsn.org/volcanoes
For information on USGS volcano alert levels and notifications: https://www.usgs.gov/programs/VHP/volcano-notifications-deliver-situational-information

Jon Major, Scientist-in-Charge, Cascades Volcano Observatory, jjmajor@usgs.gov

General inquiries: vhpweb@usgs.gov