Glaciers and perennial snowfields are important to alpine ecosystems and regional hydrology. Quantifying volume change of a population of glaciers widely distributed over a region is difficult and expensive. We employed NASA’s novel Airborne Glacier and Ice Surface Topography Interferometer (GLISTIN) to rapidly map surface topography of alpine glaciers across the western USA. In five flight days 3289 glaciers and perennial snowfields were surveyed. Comparison with lidar over control sites showed a mean difference of +0.17 ±1.78 m at a spatial scale of 3 m. Data coverage increased and elevation uncertainty decreased with the mosaicking of multiple passes due to the complex terrain. Elevation change since the National Elevation Dataset shows a thinning (and volume loss) over the last ~56 years, averaging -0.3 ± 0.2 m and accelerating since 1980. GLISTIN can be a valuable tool for rapidly mapping ice surfaces in the alpine environment.

In 2015, the Olympic Mountains contain 255 glaciers and perennial snowfields totaling 25.34 ± 0.27 km2, half of the area in 1900, and about 0.75 ± 0.19 km3 of ice. Since 1980, glaciers shrank at a rate of -0.59 km2 yr-1 during which 35 glaciers and 16 perennial snowfields disappeared. Area changes of Blue Glacier, the largest glacier in the study region, was a good proxy for glacier change of the entire region. A simple mass balance model of the glacier, based on monthly air temperature and precipitation, correlates with glacier area change. The mass balance is highly sensitive to changes in air temperature rather than precipitation, typical of maritime glaciers. In addition to increasing summer melt, warmer winter temperatures changed the phase of precipitation from snow to rain, reducing snow accumulation. Changes in glacier mass balance are highly correlated with the Pacific North American index, a proxy for atmospheric circulation patterns and controls air temperatures along the Pacific Coast of North America. Regime shifts of sea surface temperatures in the North Pacific, reflected in the Pacific Decadal Oscillation (PDO), trigger shifts in the trend of glacier mass balance. Negative (‘cool’) phases of the PDO are associated with glacier stability or slight mass gain whereas positive (‘warm’) phases are associated with mass loss and glacier retreat. Over the past century the overall retreat is due to warming air temperatures, almost +1oC in winter and +0.3oC in summer. The glaciers in the Olympic Mountains are expected to largely disappear by 2070.

Taylor Glacier, located in the McMurdo Dry Valleys of Antarctica has piqued curiosity since the first observations in 1903. Episodic release of iron-rich brine at or near the glacier terminus rapidly oxidizes, forming a visually striking red stain on the ice and glacier forefield called ‘Blood Falls’. The triggering mechanism behind these releases is unknown. The recent history of brine releases have been well documented since the 1993-94 summer season. To better understand the frequency and extent of brine releases over a longer time period we compile a detailed history of observations of the Taylor terminus from photographs, journals, field reports, oral histories, and published papers prior to the onset of more frequent monitoring in the 1990s. We developed a confidence assessment framework for our interpretation of the presence/absence of brine icing deposits. Results show that of the 30 summer seasons between 1903-1904 and 1993-1994 with interpretable observations, 21 seasons (70%) show evidence of brine flow events, and 9 seasons show no evidence of brine flow. At least two of these brine flow events are newly reported by our study. Concurrent observations of the glacier terminus over the same period showed a localized advance and collapse of a small portion of the southern terminus. We demonstrate a framework to fuse multiple data types and qualitatively assess the confidence level of our interpretations that could be applied to similar investigations of environmental history. We encourage other researchers to explore and contribute to the growing collection of open access historical archives.