You may feel that we all have enough to worry about, and thus have no need for the spectre of zombie-like reanimated bacteria or viruses in thawing permafrost that set off a story straight out of a sci-fi flick. Unfortunately, it's a looming reality thanks to climate change. 

Luckily, scientists tell us that while it's high time we thought carefully about how we are going to manage the vast numbers of microbes being released along with equally vast quantities of melting ice and thawing permafrost as a result of global heating, there is no need to panic nor to sensationalize the issue.

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When Salon spoke with microbiologist Luis Andrés Yarzábal, an associate professor at the Universidad Católica de Cuenca in Ecuador, he was indeed careful to avoid sensationalizing the problem. But he noted that we've been aware since the '80s of dramatic quantities of microbes found in even the most pristine of Antarctic ice sheets or on top of mountains, such as the Andean glaciers, and in permafrost. The host of life on ice includes bacteria, viruses, fungi, protozoa, even microscopic animals like nematodes, some dead and some alive in suspended animation.

Yarzábal actually started studying the microbiology of the Andean glaciers, beginning in Venezuela 17 years ago, because he and his team were interested in the biotechnological potential of cold-loving, or psychrophile, microorganisms. 

"They can be used, for instance, for agricultural purposes, to improve agriculture in cold regions, in mountainous regions." But the country's glaciers melted, and as they did, it revealed huge numbers of pathogens in the melting ice. Some of these disease-causing bugs may be so old, human immune systems are totally naïve to them, which means unleashing them could infect millions, maybe even trigger another pandemic. The odds of such an event may be remote — we don't actually know how likely this all is — but we do know the likelihood isn't zero and it will increase as the world's ice retreats.

"Venezuela is now the first country in the modern world to have lost all its glaciers, and there were many, many pathogens," Yarzábal said. Some are very similar to modern human pathogens. From bioprospecting beneficial microbes, he was now forced to consider less cheery possibilities. After all, Venezuela's lost glaciers were far from the only ones releasing water that has been frozen for tens or hundreds of thousands of years. Newly published research in Nature suggests that between 2000 and 2023, the world's glaciers lost some 275  gigatonnes, give or take, in mass annually, with the rate of melting increasing substantially more recently.

Disrupting the ecological equilibrium always has the potential to cause hazards to human health directly.

"The rate at which we lost ice during these 23 years is approximately the amount of water contained in four Olympic pools, per second. So that's a lot of microbes that will disperse around the ecosystems, aquatic and terrestrial ecosystems," said Yarzábal, who published a 2021 review with two colleagues........

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