ANOTHER (CHILLY) ECOSYSTEM THREATENED

When you consider how much of the habitable areas of our planet is sustained by water flowing from mountain snow, ice sheets and glaciers (what can usefully be termed the “cryosphere”), the worries about the increasing loss of these frozen water reservoirs (over 70% of the Earth’s fresh water is in them) become great indeed. Although I have touched on this previously in these short Insight notes, what I have not mentioned before is that, though we tend to think of snow and ice as lifeless, these vast but shrinking areas of ice and snow are not sterile but are teeming with microbial life. Research[1] reveals that is very far from the truth. Microbes (bacteria, archaea, algae, and fungi) are not just passive inhabitants of these frozen regions; they play crucial roles in shaping the ecology and even the chemistry of the frozen ecosystem of snow and ice.

These microbes in polar and glacial environments endure some of the harshest conditions on our planet with sub-zero temperatures, intense ultraviolet radiation, and limited nutrients. Many have evolved special adaptations, such as “antifreeze” proteins to prevent ice-crystal damage or pigments that act as natural sunscreens. These traits make them model organisms for understanding life in extreme environments. Indeed, such microbes are often termed “extremophiles”.

The algae in snow, for example, can bloom on the surface of glaciers, colouring the ice in shades of green, red, or purple. These blooms reduce the ice’s albedo (how much it reflects light), allowing more sunlight to be absorbed. This, in turn, accelerates melting. In this way, microbes directly influence glacier dynamics and contribute to feedback loops in global climate systems.

Other microbes recycle scarce nutrients by breaking down organic matter, fixing nitrogen, or supporting simple food webs of microscopic grazers. In seemingly barren ice, they create “microbial ecosystems” that sustain biodiversity and biogeochemical cycles.

Although microscopic, these microbial communities can have planetary-scale effects. By influencing the melting of ice, they affect sea-level rise and climatic responses. By storing and cycling carbon, they connect frozen ecosystems with the broader global carbon cycle. And by thriving in isolation for thousands of years, microbes trapped in deep glacial ice offer a way to observe Earth’s past climate and biology.

Far from being sterile deserts, glaciers and polar snowfields are living landscapes shaped, in part, by microbial life. Studying these organisms is deepening our understanding of Earth’s changing “cryosphere”, but also highlights the resilience of life in places where survival would, at first glance, seem impossible. The decline of this cryosphere ecosystem through global warming is, though, yet another very serious concern as humans continue to degrade our world.

Betts Ecology continue to make sure we are aware of all aspects of climate change and what we can do to communicate and help through corporate policies.

[1]

An internet search will provide you with much more detail and here are some of the sources worth consulting if you want to know more about this fascinating but worrying and urgent topic.

• Psychrophile adaptations; snow algae and albedo impact:
• https://www.nature.com/articles/s41522-017-0019-0 The microbiome of glaciers and ice sheets (Nature)
• Bradley JA, Trivedi CB, Winkel M, Mourot R, Lutz S, Larose C, Keuschnig C, Doting E, Halbach L, Zervas A, Anesio AM, Benning LG. (2023) Active and dormant microorganisms on glacier surfaces. Geobiology. https://pmc.ncbi.nlm.nih.gov/articles/PMC10099831/?utm_source=chatgpt.com.

Also The Guardian’s science articles such as by Ben Martynoga are an excellent source.