Scientists find and revive 48,500 year-old frozen 'zombie' virus, warn about climate change

The Arctic region is experiencing warmer temperatures, which are causing permafrost to thaw. Permafrost is a frozen layer of soil beneath the ground that has preserved ancient viruses and other materials for tens of thousands of years. As a result, there are concerns that these viruses, which have been lying dormant till now, could revive and pose a risk to animal and human health.

According to CNN, Jean-Michel Claverie, an Emeritus professor of medicine and genomics at Aix-Marseille University School of Medicine in France, has been studying earth samples taken from Siberian permafrost to determine whether any viral particles are still infectious. He refers to these viruses that he has found as "zombie viruses." Although the risks of a pandemic caused by these ancient viruses are low, scientists warn that the risks should not be underestimated.

There are also concerns about the release of chemical and radioactive waste from the Cold War era, which could harm wildlife and disrupt ecosystems during thaws. This highlights the importance of keeping as much of the permafrost frozen as possible, according to Kimberley Miner, a climate scientist at NASA Jet Propulsion Laboratory in California.

Permafrost covers a large portion of the Northern Hemisphere and has been a vital part of the Arctic tundra and boreal forests for millennia. It has served as a storage medium for many ancient materials, including the mummified remains of extinct animals like cave lion cubs and a woolly rhino. However, the permafrost is not just cold, but also an oxygen-free environment where light cannot penetrate, making it an excellent preservation medium. Unfortunately, the current Arctic temperatures are warming up to four times faster than the rest of the planet, leading to the weakening of the top layer of permafrost in the region.

Claverie, who found this 48,000-year-old virus, has been working on unearthing ancient viruses since 2003 and was inspired by a team of Russian scientists who in 2012 revived a wildflower from a 30,000-year-old seed tissue found in a squirrel’s burrow. In this latest research, he worked with his team to find stains of viruses from different parts of Siberia. The oldest of the stains, based on radiocarbon dating of the soil, were more than 40,000 years old. These were discovered from a sample of earth taken from an underground lake 16 meters (52 feet) below the surface. The youngest samples, found in the stomach contents and coat of a woolly mammoth’s remains, were 27,000 years old.

According to Kimberley Miner, a lot is going on with the permafrost that is cause for concern. Therefore, it’s essential to keep as much of the permafrost frozen as possible. Permafrost covers a fifth of the Northern Hemisphere, providing the foundation for the Arctic tundra and boreal forests in Alaska, Canada, and Russia for thousands of years. It serves as a time capsule, preserving the mummified remains of extinct animals that have been recently discovered, such as two cave lion cubs and a woolly rhino.

Permafrost is an excellent storage medium not only because it’s cold, but also because it’s an oxygen-free environment with no light penetration. However, current Arctic temperatures are warming up to four times faster than the rest of the planet, weakening the top layer of permafrost in the region.

This is not the first time that scientists have found dormant viruses of this sort. A lung sample from a woman's body exhumed in 1997 from permafrost in Alaska contained genomic material from the influenza strain responsible for the 1918 pandemic. And a 300-year-old mummified remains of a woman buried in Siberia contained the genetic signatures of the virus that causes smallpox. 

The thawing of permafrost has also been linked to the resurgence of old spores of Bacillus anthracis, which caused an anthrax outbreak in Siberia in 2016 that affected humans and reindeer. Birgitta Evengård, a professor emerita at Umea University’s Department of Clinical Microbiology, has called for better surveillance of the risk posed by potential pathogens in thawing permafrost.

However, she cautioned against an alarmist approach and emphasized that our immune defenses have developed in close contact with microbiological surroundings. She also stressed the importance of being proactive rather than reactive and acquiring knowledge to fight fear.

Although it is unknown how long these viruses could remain infectious or how likely they are to encounter a suitable host, the risk is bound to increase in the context of global warming, which will accelerate permafrost thawing and lead to a higher population in the Arctic due to industrial ventures. While the Arctic is still sparsely populated, a team of scientists has found that the risk of viruses spilling over to new hosts is higher at locations close to where large amounts of glacial meltwater flow into freshwater lakes in the Arctic.