By: Jessica J.
Global warming is causing the permafrost soils to melt that are more than hundreds of thousands years old, and as the soils thaw ancient bacteria and viruses that were dormant have now resurrected.
What is Permafrost?
Permafrost is ground that remains frozen for at least two consecutive years. It is essentially a combination of rock, soil, sediment, ice, and organic material. These frozen grounds are most commonly found in regions with high altitudes and latitudes.
Permafrost Structure. Photo retrieved from The Stars Project
As Earth’s climate warms, the permafrost has started to thaw, which results in the ice inside to thaw. This can lead to dramatic impacts to the planet and living organisms. For example, the many villages in the polar and high altitude areas face the threat of structural damage to their houses, and roads, because they are built on top of the permafrost. Another example is the microbes start decomposing the organic material found in the permafrost, which releases greenhouse gases and methane into the atmosphere. Finally, as it thaws ancient bacteria and viruses spring back to life after being preserved cryogenically for thousands of years.
Permafrost melting loop. Diagram retrieved from Earth.org
Discovery of the Hidden Bacteria and Viruses
A study that collected ice cores from the Guliya ice cap on the Tibeatan Plateau in 1992 and 2015, discovered that the exterior of these ice cores were contaminated, while the insides were still in their pristine ancient conditions. Once the exterior of the ice cores were sterilized, they reached an uncontaminated (by modern microbes) layer to study. The deep layer revealed 33 distinct groups of virus genuses, of which 28 were previously never observed scientifically.
Ice cores collected by researchers. Photo retrieved from:UC Berkeley
Bacteria found in an ice core. Micrograph retrieved from: Research Gate
In 2014, where a group of scientists discovered a giant virus (almost 50% more bigger than the virus that was up until that point known to be the biggest virus), was found in a 30,000 year old ice core. The virus was found to still be infective.
How are they there?
According to evolutionary biologist Jean-Michel Claerie, at Aix-Marseille University in France, permafrost is “a very good perseverer of microbes and viruses, because it is cold, there is no oxygen, and it is dark”. As snow falls it traps air, water, and microbes, and as more snow falls those layers get compacted and form solid ice that traps those materials in place.
Bacteria are able to stay dormant while being cyronigically trapped in the ice.
Photo retreived from: Frontiers for Young Minds
How are they emerging?
As the ice starts to melt the bacteria and virus could escape through various ways. The ice can be thought of as a natural bank of various dormant propagules such as seeds, eggs, cysts, and spores from plants and invertebrates. Another viable for the spread of a bacteria or virus is when the body of infected deceased animals or humans is preserved in the ice, by not decomposing. When the ice thaws, the bacteria or virus would be able to replicate and transfer itself to another host.
Spores collected from Antarctic Ice. Photo retrieved from: Research Gate
Recent Impacts
In December 2016, a remote community in Salekhard,Siberia, experienced a strange outbreak that resulted in the hospitalization of 90 people, and the death of a young boy. Russian officials found out that the highly infectious disease anthrax had killed him. The outbreak had started among reindeer, however, there hadn’t been an anthrax breakout in the area for more than 70 years. After scientists began looking underground, they believed the outbreak originated from the carcass of an infected reindeer that had died a long time ago. Anthrax spore from the carcass would have spread across the area, and the nearby reindeers.
Photo retrieved from: ABC
What Does All this Mean For the Future?
Scientists worry as the permafrost melts various pathogens could revive various diseases thought to have been eradicated (such as the Spanish flu, bubonic plague, and smallpox), or never before seen.
Discussion Question:
Why is the melting of permafrost a positive feedback loop (response of a system to a change that causes a higher magnitude of change in the same direction)?
What are some other impacts as a result of melting glaciers and ice caps?