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The « snow melon’

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An ecosystem unique micro-organisms such as algae and fungi are responsible for the unusual reddish tint that snow sometimes takes on.

Radio-Canada

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A new study by researchers from Simon Fraser University, in British Columbia, demonstrates that the phenomenon of “watermelon snow”, also known as “glacier blood”, represents a threat to glaciers and in particular the glaciers of mountain.

The Rocky Mountains thus give a colorful appearance in their hostile upper part. This is the phenomenon of watermelon snow, which consists of a thin layer colored red-orange. It is caused by algae that gives snow a striking red hue.

The darker the snow, the faster it melts. Researchers shed light on the threat that snow algae poses to shrinking glaciers in northwest North America.

Professor of molecular biology and biochemistry at Simon Fraser University, Lynne Quarmby is a snow algae researcher and lead author of a recent study (New window) (in English) published in Science Advances. She emphasizes that the research results are a warning against climate change.

The disappearance of algae is only one indicator of the disappearance of the mantle snow and glaciers, which will impact our lives and the lives of many other organisms.

A quote from snow algae researcher Lynne Quarmby

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ELSE ON NEWS: Boeing 737 MAX 9: torn door found, but questions remain 48221190-4 hnvfyV”>The study mapped the presence of snow algae on the mountains of Alberta, British Columbia and northern Canada, as well as the x27;Alaska, Idaho, Montana and Washington State.

Researchers developed a machine learning program to analyze more than 6,100 satellite images of glaciers taken between 2019 and 2022.

The study found that blooms of red-pigmented algae contribute to the melting of glaciers. However, global warming poses a much greater threat to mountain glaciers and to the surprisingly complex microscopic ecosystems that allow snow algae to colonize them.

Supported by a large ecosystem of bacteria and fungi, snow algae thrive when water and nutrients are released by melting snow. This phenomenon results from the proliferation of Chlamydomonas nivalis, a species of unicellular green algae that thrives at temperatures near freezing.

Relying on photosynthesis, blooms act as carbon sinks, absorbing carbon dioxide from the atmosphere.

Snow algae has a red pigment that allows it to survive in harsh mountain environments. “When they bloom, they give the snow this red tint,” explains Lynne Quarmby.

Blooms darken the surface of summer snowfields, making them less reflective of the sun, which accelerates the melting of snowpack and ice.

The darker shade also acts as a parasol, protecting algae from sun damage.

Quarmby and her colleague Casey Engstrom of Simon Fraser University set out to create a large-scale map of microscopic ecosystems. They found that between 2019 and 2022, reddish snow covered more than 4,214 square kilometers of the glacial landscape, or 4.5% of the total study area. The impact [of algae] is perceptible, it is real, she says.

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Every summer, colorful algae colonize thousands of snowfields in North America.

Researchers estimate that colored snow contributed an average of three centimeters of snowmelt water per season.

Snow algae contributed were found on 4552 of the 8700 glaciers studied. Some had only one patch, while others had large blooms. For example, in 2020, algae covered nearly two-thirds of the surface of Alberta's Bow Glacier in the Wapta Icefield.

Glaciers along the Pacific Northwest coast are usually teeming with algae, but during the heat dome three years ago, the ice melted so quickly that the blooms of the ice melted. water did not have time to develop.

According to Lynne Quarmby, when the snow begins to disappear with rising temperatures, the algae will also disappear. This will mean the loss of a valuable ecosystem that scientists are only beginning to understand.

According to Scott Hotaling, an ecologist from At Utah State University which was not involved in the study, the research findings of Lynne Quarmby and Casey Engstrom provide an important baseline for evaluating the impact of snow algae on retreating glaciers.

With information from Wallis Snowdon

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