As global temperatures climb the Earth frozen regions are rapidly thawing and with them a Pandora box of microbial dangers is beginning to open. The United Nations Environment Programme (UNEP), in its Frontiers 2025: The Weight of Time report released on July 10 has warned that retreating glaciers and melting permafrost are reactivating ancient microorganisms and releasing antimicrobial resistance (AMR) genes, posing new threats to ecosystems and human health.
The report highlights how the cryosphere which includes glaciers, permafrost, sea ice, and frozen ground is at the frontline of the climate crisis. It spans over half the planet’s land surface and supports vital freshwater supplies for hundreds of millions of people. But with Arctic sea ice shrinking rapidly and glaciers projected to lose up to half their volume even if warming is limited to 1.5°C, irreversible change is already underway.
One of the most alarming risks is the revival of ancient viruses, bacteria, and fungi some preserved for tens of thousands of years. These microbes once reawakened could potentially interact with modern ecosystems in unpredictable ways. The report points to the 2016 anthrax outbreak in Russia’s Yamal Peninsula as a warning. Thawed permafrost released dormant Bacillus anthracis spores, leading to the death of thousands of reindeer and infecting dozens of humans.
Beyond direct infections, thawing ice could also accelerate the global health crisis of antimicrobial resistance. Microbial communities preserved in glaciers and frozen soils have been found to contain thousands of AMR genes, including resistance to modern antibiotics like tetracycline, streptomycin, and beta-lactams. These genes, if transferred to contemporary pathogens, could undermine existing treatments and escalate the threat of superbugs.
The report further notes that microbial samples retrieved from Tibetan glaciers, Antarctic ice cores Siberian permafrost, and the Himalayas contain virulence factors and cold-adapted organisms. These psychrophiles cold-loving microbes have evolved survival strategies that allow them to remain dormant for millennia. In 2023, researchers revived a roundworm frozen in Siberia for 46,000 years, which resumed life and reproduction.
While some of these microbes are useful in biotechnology and pharmaceuticals, the ecological and health risks of releasing unknown organisms and AMR genes far outweigh the benefits, UNEP cautions.
To limit further damage the report urges immediate action to reduce emissions, particularly black carbon a short-lived climate pollutant from diesel engines, wildfires, and crop burning. Black carbon darkens ice surfaces, reducing their reflectivity and accelerating melt.
Other recommendations include restricting tourism in fragile icy regions and using reflective sheets to slow glacier melt, though the latter is considered impractical for large-scale application and may lead to microplastic pollution.
Ultimately UNEP warns that cryospheric loss is a clear sign of humanity failure to cut greenhouse gas emissions in time. As once-stable ecosystems unravel, the world must now grapple with newly emerging biological threats while trying to preserve what little remains of Earth frozen legacy.