Sperry Glacier is located 25 miles south of the border between the United States and Canada, in Montana’s Glacier National Park. It is a winter-accumulation glacier, as more snow falls during the winter than is lost during the summer. The moderate-sized glacier can be reached by foot or on horseback, rising to an elevation of around 7,800 feet. The glacier was named for doctor Lyman Beecher Sperry, who in 1894 reasoned that the glacier was the cause of the cloudiness of the water in Avalanche Lake. When Sperry and his party first reached the glacier in 1897, his nephew Albert Sperry had this reaction after viewing the glacier:
While standing upon that peak overlooking the terrain above the rim wall, we got the thrill of thrills, for there lay the glacier, shriveled and shrunken from its former size, almost senile, with its back against the mountain walls to the east of it, putting up its last fight for life. It was still what seemed to be a lusty giant, but it was dying, dying, dying, every score of years and as it receded, it was spewing at its mouth the accumulations buried within its bosom for centuries.
Today, you can visit Sperry Glacier and walk along the same route that Sperry and his party traveled 120 years ago, although the glacier looks very different today. Join us on this visual tour of the glacier’s past and present. We hope that concerted action on greenhouse gas emissions will assure that this beautiful glacier has a future.
The increase of heat-trapping greenhouse gases in Earth’s atmosphere is warming the Antarctic Peninsula at a unprecedented rate. A recent study from Angulo-Preckler et al. in Continental Shelf Research explores whether significant decreases in sea ice and melting glaciers in the waters west of the Antarctic Peninsula favor some species of marine life and harm others. Among the species which call the waters home, the authors of this study focus on echinoderms, an invertebrate phylum that includes starfish, sea urchins and brittle stars.
Accounting for approximately 45 percentof biomass on the ocean floor west of the Antarctic Peninsula, echinoderms live between the intertidal zone and the sea floor. With no heart, brain or eyes, echinoderms use tentacle-like structures with attached suction pads on their appendages to slowly traverse underwater surfaces. As filter-feeders, echinoderms grab their prey with tentacles, consuming it through a mouth located on their underside. Although echinoderms already live in an environmentally challenging location, with water temperatures reaching 0°C and below, melting glaciers are adding an additional level of complexity to their ecosystem.
For example, on Deception Island, a volcanically-active island in the South Shetland Islands archipelago, physical disturbance from the volcano and glacier retreat are causing alterations to the ecosystem. Deception Island’s volcano last erupted in 1970, yet volcanic ash from that eruption and previous eruptions settled on nearby glaciers. As the glaciers melt, volcanic ash travels from glacial surfaces to the marine waters below.
In turn, mixing marine waters distribute volcanic ash to depths where echinoderms dwell in a process called sedimentation. This impacts the survival of some echinoderms as they are incapable of thriving under high levels of sedimentation. High sedimentation is problematic for certain species because the additional material prevents them from easily inhabiting crevices between rocks and sponges.
Port Foster, a bay encompassed by Deception Island, is fed by the surrounding melting glaciers. Angulo-Preckler et al. examined eight different locations in the Deception Island bay, at both 5 meters and 15 meters, to determine a relationship between high sedimentation rates and the number of echinoderms. The study found three dominant echinoderms – the brittle star (Ophionotus victoriae), the Antarctic sea urchin (Sterechinus neumayeri) and the Southern Ocean starfish (Odontaster validus) – are coping well to the high sedimentation rates, at the expense of other echinoderms.
The researchers found that the opportunistic brittle star and sea urchin are now dominating areas of Deception Island Bay by replacing other echinoderms, such as the sea cucumber. Where there was once a large variety of species, there are now just three main echinoderms. This reduction in biodiversity has implications for the health of the ecosystem.
High ash sedimentation from the volcano and high sedimentation rates due to the retreat of glaciers could decrease biodiversity levels at Port Foster by forcing other species out of their habitat. Since the last eruption, many of the echinoderms that once flourished in the area have now disappeared. As the region continues to warm, research suggests that increasing sedimentation from melting glaciers could continue to impact the communities of the intertidal and benthic zone of western Antarctica.
Ricardo Sahade,an Antarctic ecologist from the National University of Córdoba in Argentina, confirmed to GlacierHub that “coastal ecosystems experiencing glacier retreat can be threatened by increased sedimentation.” More sedimentation and melting glaciers change the composition of echinoderm habitat. Further research will provide fuller details on whether higher sedimentation reduces biodiversity in this marine ecosystem. Even now, it is evident that disturbances from retreating glaciers are changing the Antarctic ecosystem and the habitat it provides.
Retreating Coronation Glacier Forms New Deltaic Island
From American Geophysical Union: “In 1989 Coronation Glacier (Nunavut, Canada) terminates where the main outlet stream has created a pair of small deltaic islands on the northern side of the fjord. In 2016 a new deltaic island has formed near the southern edge of the margin, indicating a shift in the position of the main river outlet emanating from below the glacier, this is also marked by a large plume. The island formed is larger than those observed in 1989 or 1998. The size of the island gives it potential to survive, based on satellite imagery. A visit to the island would be needed to shed light on its potential for enduring. Retreat from 1989 to 2016 has been 1100 meters on the northern side of the fjord and 500 meters on the south side of the fjord. The average retreat of 800 meters in 27 years is over 30 meters/year, much faster than the 1880-1988 period.”
From Microbial Ecology: “The Watson River drains a portion of the southwest Greenland ice sheet, transporting microbial communities from subglacial environments to a delta at the head of Søndre Strømfjord. This study investigates the potential activity and community shifts of glacial microbiota deposited and buried under layers of sediments within the river delta. A long-term (12-month) incubation experiment was established using Watson River delta sediment under anaerobic conditions, with and without carbon dioxide/hydrogen enrichment. The results highlight the need for further investigations into the fate of subglacial microbiota within downstream environments.”
Learn more about subglacial microbial communities here.
Improving Glacier Bed Topography Mapping
From Oceanography: “Melting of the Greenland Ice Sheet has the potential to raise sea level by 7.36 meters and is already contributing to global sea level rise at a rate higher than 1 milimeter/year. Computer models are our best tools to make projections of the mass balance of Greenland over the next centuries, but these models rely on bed topography data that remain poorly constrained near glacier termini. We combine here for the first time mass conservation glacier bed mapping and newly collected bathymetry data from NASA’s Oceans Melting Greenland (OMG) to evaluate and improve descriptions of bed topography under grounded ice near glacier termini, where it matters most for improving the reliability of ice sheet models.”
Read more about NASA’s Oceans Melting Greenland data here.