Permafrosts Reservoirs for a potential revival of ancient pathogens

Biodiversity is the variability among living organisms on Earth, and it reflects billions of years of evolutionary history. However, biodiversity at the microorganism–environment–human interface may present risks as reservoirs of potential human pathogens, especially if the harmony of the ecosystem is disturbed by specific environmental perturbations. As climate change comes out as a major challenge that humanity faces right now, it is also widely recognized to impact the biodiversity on Earth significantly.

The interconnectivity of human health to the equilibrium of the ecosystem becomes cruelly apparent when outbreaks of zoonotic (when a pathogen that has jumped from animal to human causes an infectious disease) infections occur. Some of the outbreaks have lower spreading rates and cause epidemics (such as Ebola virus disease), whereas others rarely go on to cause pandemics as we impactfully face nowadays with the SARS-CoV-2 virus.

We see another example of the disturbance of the ecosystem's balance in the thawing of the permafrost regions globally under a constantly changing climate. Unfortunately, this is a positive feedback loop since greenhouse gas release from thawed permafrost to the atmosphere may, in turn, increase global warming more. More importantly, the amount of carbon in permafrost is four times the carbon that has been released into the atmosphere due to human activities of our times.

So what is this permafrost? Permafrost is the thick subsurface layer of soil that remains frozen, at or below 0˚C continuously for more than two consecutive years, while the upper part of the soil that thaws every summer is called the active layer. This frozen layer below the Earth may consist of earth materials like soil, rock, sediment, ice, and prehistoric organisms, potentially containing some dormant ancient pathogens.

Permafrost occurs in cold climate regions of high latitudes or high altitudes extending to 25% of the Northern Hemisphere's exposed land surface, mainly Russia (Siberia), Canada, Alaska, China, and Greenland. As global warming threatens to increase the average temperature each year in these regions, the active layer thawing each summer is under the risk of increasing, resulting in the slow degradation of permafrost worldwide. This degradation of permafrost has resulted in profound hydrological, ecological, and socio-economic consequences. Thawing permafrost worldwide has a massive impact on the local ecosystems, economies, landscape, and topography, causing infrastructure damage, landslides, and coastal erosion.

Another potential threat of permafrost degradation is concerning the revival of prehistoric pathogens. Melting of the parts isolated from the rest of the world for tens of thousands of years increases the risk of the ancient pathogens lying in the permafrost lurking into the active layer's soil, posing a potential threat to our modern lives.

A recent example of this case was observed in the anthrax (Bacillus anthracis) outbreak in northern Siberia, affecting a dozen humans and the culling of a few thousand reindeers. The outbreak is thought to be caused by the exposure of a carcass of a reindeer that is killed by anthrax more than 75 years ago. The heatwave that hit Siberia in 2016 caused the thawing of the permafrost layer that preserved the carcass for decades and resulted in resurfacing of the carcass and the anthrax bacteria.

Since climate change is causing the temperature in the Arctic Circle to rise very quickly, there are likely to be more cases of anthrax resurfacing.

Since it is challenging to monitor the condition of permafrost from the surface or satellite images, it is necessary to drill through it to assess its properties. We need to design and apply novel and innovative environmental and engineering projects to protect the permafrost environments under the influence of global warming in the affected regions, enabling proactively adapting to the changes with the latest technologies.

Could the next pandemic be hiding in permafrost somewhere on Earth?

Dr. Burcu Aykaç Fas


Boren, Z. (2020). The permafrost pandemic: could the melting Arctic release a deadly disease?

Doucleff, M. (2016). Anthrax Outbreak In Russia Thought To Be Result Of Thawing Permafrost.

Fisher, M. C., & Murray, K. A. (2021). Emerging infections and the integrative environment-health sciences: the road ahead. Nature Reviews Microbiology, 1-3.

Jin, H., Wu, Q., & Romanovsky, V. E. (2021). Degrading permafrost and its impacts.

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