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Warmer temperatures in the Arctic are melting permafrost and could "awaken" viruses that have been dormant for tens of thousands of years.
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| An ancient virus was isolated from a sample of permafrost. |
Viruses can become infectious after 30,000 years.
During the melting process, chemical and radioactive waste from the Cold War can also be released, potentially threatening the lives of plants and animals in nature and disrupting ecosystems. Kimberley Miner, a climate scientist studying jet engines at NASA's California Institute of Technology, emphasized: "Many of the phenomena occurring with this permafrost layer are concerning, and that shows why we must preserve as much permafrost as possible."
Permafrost, covering one-fifth of the Northern Hemisphere, has fortified the Arctic tundra and the northern forests of Alaska, Canada, and Russia for millennia. Permafrost is an excellent storage medium, not only because it is cold, but also because it is an oxygen-free environment where light cannot penetrate. However, temperatures in the Arctic today are warming four times faster than the rest of the Earth, weakening the region's top permafrost layer.
To better understand the risks posed by frozen viruses, Jean-Michel Claverie, Professor Emeritus of Medicine and Genetics at Aix-Marseille University in Marseille, France, tested soil samples taken from permafrost in Siberia (Russia) to determine if any viruses contained within were still capable of spreading. The scientist stated that he was searching for “zombie viruses” and had found several species. Claverie studied a specific virus he first discovered in 2003, known as a giant virus. These are much larger than the common type and are visible under a microscope with normal light, rather than a more powerful electron microscope. In 2014, Professor Claverie revived a 30,000-year-old virus, which he and his colleagues isolated from permafrost, making it infectious by injecting it into cultured cells. For safety reasons, he chose to research a type of virus that could only infect single-celled amoebas, not animals or humans.
Claverie repeated this success in 2015 when he isolated another virus that also only infects amoebas. In the latest study, published in the journal Viruses on February 18, Claverie and his colleagues isolated several ancient virus strains from samples of permafrost taken from seven different locations in Siberia and showed that they could infect cultured amoeba cells. These newest strains represent five new virus families, in addition to the two families he had previously revived. The oldest sample is nearly 48,500 years old, based on radiocarbon dating of the soil.
Potential threat
Claverie argues that the virus infecting amoebas after a long period of "hibernation" is a sign of a larger underlying problem. He fears people will view his research as mere scientific curiosity and fail to see the prospect of ancient viruses reviving as a serious threat to public health. Professor Emeritus Birgitta Evengard at the Department of Clinical Microbiology, Umea University (Sweden), believes better monitoring of the risks from potential pathogens in thawing permafrost layers is needed, but there should be no panic. Despite having 3.6 million inhabitants, the Arctic remains sparsely populated, thus the risk of human exposure to ancient viruses is very low. However, the risk will increase in the context of global warming.
In 2022, a group of scientists published research on soil and lake sediment samples taken from Lake Hazen, a freshwater lake in Canada located in the Arctic region. They sequenced genes in the sediment's genetic material to identify traces of viruses and the genomes of potential host plants and animals in the area. Using a computer modeling analysis, the scientists concluded that the risk of the virus spreading to new hosts is higher in locations near where large amounts of melting ice flow into the lake – a scenario more likely in the context of a warming climate.
According to Miner, the reappearance of ancient microorganisms capable of altering soil composition and plant growth could accelerate the effects of climate change. Therefore, Miner argues that the best approach is to try to halt the melting ice and the climate crisis, thereby keeping these dangers buried forever in the permafrost.
Scientist Kimberley Miner argues that it is currently unlikely that humans will directly contract ancient pathogens released from permafrost. However, Miner is concerned about microorganisms she calls Methuselah (named after a biblical character with the longest lifespan). These microorganisms could introduce the dynamics of ancient ecosystems (a set of continuous changes occurring in the environment and its biological components) into the modern Arctic, with unforeseen consequences.
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