Melting Glaciers Could Release Deadly Microbes, Scientists Suggest

David Bressan
Contributor
I deal with the rocky road to our modern understanding of earth

Jun 28, 2022

Artist's impression of viruses trapped in glacier ice. GETTY

Last year, scientists announced the discovery of 33 viruses in ice and snow samples collected from glaciers. Now another study found almost 1,000 species of bacteria in similar samples.

Most of those microorganisms, which survived because they had remained frozen, are unlike any microorganisms that have been cataloged to date.

The researchers analyzed ice cores taken from Tibetan glaciers. The ice cores contain layers of ice that accumulate year after year, trapping whatever was in the atmosphere around them at the time each layer froze - including microbes and viruses.

"These glaciers were formed gradually, and along with dust and gasses, many, many viruses were also deposited in that ice," said microbiologist Zhi-Ping Zhong, lead author of the 2021 study published in the journal Microbiome.

Thanks to improved methods to detect and extract genetic material from frozen samples, a team of Chinese researchers now identified 968 unique species of bacteria in 21 samples recovered from Tibetan glaciers. The discovery was published in the journal Nature Biotechnology.

The study of viable microorganisms in glaciers is a relatively new branch of science. In 2015, a study published in the Proceedings of the National Academy of Sciences found that the 30,000-year-old virus Mollivirus sibericum could still infect modern amoeba. In 2020, a preprint study described ancient viruses found in samples from a melting glacier in Tibet.

"We know very little about viruses and microbes in these extreme environments, and what is actually there," explains Lonnie Thompson, a glaciologists involved in the research. "The documentation and understanding of that is extremely important: How do bacteria and viruses respond to climate change?"

As glaciers all over the world are melting at an alarming rate, the released microbes could travel with the meltwater into rivers and streams and reach populated areas, infecting plants, animals and people. The glaciers in Tibet feed several rivers that lead to densely populated regions of China and India. As some of the bacteria and viruses are very old - some are older than 15,000 years - modern organisms could lack immunity to these microorganisms.

In the worst-case scenario, meltwater from glaciers and ice caps could release potentially infectious pathogens into the environment. Researchers have found still intact smallpox and the Spanish flu viruses in 100-year-old frozen tissue samples. An outbreak of anthrax in Siberia five years ago is believed to be the result of the pathogen preserved in reindeer carcasses. Frozen for decades, the bodies thawed out of the ground during an exceptional heatwave, releasing the still infectious anthrax spores.