A recent New York Times interactive article documents the changes of glaciers around Washington State and Alaska. The melting of these glaciers has a heavy impact on more than just sea level rise. It impacts salmon spawning, river and stream patterns, and nearby landscapes. Changes to glaciers also impact the nutrient balance and temperature of glacier-fed watersheds. These disruptions can shift a whole ecosystem.
Climate reporter Henry Fountain and photographer Max Whittaker ventured to Alaska and the Pacific Northwest to evaluate the impacts of melting glaciers on local ecosystems.
Glacial ecosystems have adapted to fit this cold water environment. As the temperature of the water rises, it becomes more difficult for smaller species to remain in their habitat and could potentially cause them to die out.
The impact on glacial melt on salmon, however, is more complex. Salmon are major income source in the Pacific Northwest and Alaska. Though temperature is also important to salmon migration and reproduction, there could be some temporary benefits for salmon in terms of glacial melt. The melt brings rocks and boulders that were not in the river bed before, providing excellent spawning sites. Because of this, some areas could actually see an increase in salmon populations.
Recently published research by the University of Minnesota’s Trinity Hamilton and Jeff Havig reveals how increasing atmospheric carbon dioxide levels promote the growth of snow algae blooms on glaciers in the Pacific Northwest.
But the two researchers also report that snow algae dynamics on the surface lead to subglacial conditions that provide a refuge for biodiversity, which could have implications for the search for life on Mars.
Read on to find out how.
What is snow algae?
Interest in snow algae goes back to at least the days of Aristotle, who speculated in The History of Animalsabout the reasons for its color.
Snow algae are photosynthetic green algae that appear as strips or patches of red or watermelon-colored snow on the surface of glaciers. Snow algae, according to some, can also emit a watermelon-like smell.
Carotenoids are responsible for the red or pinkish color of snow algae and help protect it from the ultraviolet light, drought, and cold that are characteristic of glacier environments.
But the darker color of snow algae means its proliferation can lower albedo, which triggers melting—as much as 13 percent, according to a 2016 study.
Snow algae gets a boost from a warming world
Hamilton and Havig, writing in The ISME Journal, report a positive feedback between increased atmospheric carbon dioxide concentrations and snow-algae blooms.
“Not only is increasing CO2 leading to increased melting of glaciers from heating the atmosphere but also from increasing snow algae blooms, which darken glacial surfaces, lowering the albedo and thus increasing the heating and melting of the surfaces,” Havig told GlacierHub.
The duo conducted their research on Gotchen Glacier on Mt. Adams in Washington, Eliot Glacier on Mt. Hood in Oregon, and Collier Glacier on North Sister, also in Oregon.
In an article published in the journal Geochimica et Cosmochimica Acta, they describe how snow algae cycles carbon and nitrogen through the glacier and feeds subglacial microbial communities and weathering of the bedrock below glaciers.
“The presence of heterotrophic microorganisms in the subglacial system is a potential driver of CO2 generation as they break down organic carbon coming from the supraglacial system and convert it into CO2, which can then combine with water to form carbonic acid, a key driver of mineral breakdown and dissolution,” Harvig said.
Carbonic acid, in other words, breaks down the silicate rocks that characterize the volcanic-rock formations on top of which the glaciers formed.
Life on Mars
Considering that life thrives within the volcanic rock-hosted glaciers on Earth, might the stratovolcanoes and cryosphere of Mars also provide a refuge for biodiversity?
Hamilton and Havig are collaborating with researchers at Purdue University and Northern Arizona University to explore that very question.
“Mars is currently a glaciated planet, and so glacier-associated life may have developed there, and we are interested in looking for refugia where life could still be present or learning how to look for evidence of past life.”