You may have been warned about yellow snow but for some scientists, it's red snow that keeps them up at night.
Researchers are pointing to an emerging trend in the Swiss Alps and other icy habitats, which presents as yet another troubling side-effect of the planet's warming climate.
Dubbed by some as "watermelon snow", locals in the Swiss Alps reportedly call it “sang de glacier,” or “glacier blood.”
The source of the morbid discolouration? A quiet explosion of algae.
While some blooms turn the slopes a red or pinky colour, others produce a more typical green covering.
Alpine habitats all over the world have experienced an uptick in snow-algae blooms, The New York Times reported this week. While they're not well understood, new research in the journal Frontiers in Plant Science is helping to uncover the story of these tiny lifeforms and their potential impact.
"Green algae have been shown to be primary colonisers after glacier’s retreat," researchers wrote.
There is concern, however, that the spread of algae and the "blood snow" it producers will absorb more heat, causing the already melting snow to rescind faster, potentially speeding up the impacts of climate change.
While initial warming has aided the rise of algae in high altitude environments, the long-term consequences of warming won't be so friendly for the organisms, scientists warn.
Microbiologist Heather Maughan told The New York Times the growing alpine algae serve "as beacons of ecosystem change."
Scientists are working to establish how exactly temperature patterns correlate with blooms, she added.
"There’s so little that we know ... We need to dig deeper."
In 2020, researchers published a study in the journal Nature, presenting "the first estimate of green snow algae community biomass and distribution along the Antarctic Peninsula".
Warming in the Antarctic Peninsula, southeast of Australia, has already exceeded 1.5 °C over pre-industrial temperatures and the study's authors projected "a net increase in snow algae extent and biomass as the Peninsula warms".
Australia left isolated on climate
Australia has become even more isolated on global climate change policy after the heads of the world's largest economies agreed over the weekend to end government support for coal-fired power stations by the end of the year.
A joint statement from leaders at the G7 summit said continued global investment in unabated coal power generation was incompatible with keeping global warming to 1.5 degrees Celsius.
The statement was not designed to single out Australia but highlighted Scott Morrison's outsider status on climate change.
It also made it more difficult for the prime minister to continue resisting calls to commit to achieving net-zero carbon emissions by 2050.
It comes as the government announced it will spend taxpayer money on a feasibility study for a new coal-fired power station in Queensland.