What is a zombie virus? Zombie viruses are ancient viruses that have been frozen in ice, but are being released as the permafrost melts due to climate change. “Zombie” virus is rather a dramatic name. These viruses won’t turn people into zombies and they don’t come from zombies. They are given this name because they are dead, yet not dead.
A large part of the northern hemisphere is covered in permafrost. Approximately 15% of the northern hemisphere is permafrost, which is 18 million km2, bigger than Europe or South America. Permafrost is soil that is permanently frozen, and this is the reason why it is only in the northern hemisphere. All of the land in the southern hemisphere that could be frozen is under the Antarctic ice sheet and not exposed. To be classified as permafrost, the ground needs to be frozen (under 0℃) for two years in a row. A lot of the ground has been frozen for many years without thawing. A lot of the permafrost lies below a layer of soil that freezes and thaws every. The permafrost never thaws. The oldest measured permafrost is 700,000 years old.
Recently, because of climate change and the warming climate, the rate that permafrost is melting has started to increase. It can be seen in any country that has areas of permafrost. There are many problems when permafrost starts to melt, not least being the zombie viruses we are learning about today. One of the problems is that people live and work on permafrost. A lot of infrastructure, such as buildings, roads, and pipelines, has been built across the permafrost. When the permafrost melts, the ground becomes very soft and these structures can collapse. Another problem is landslides. When the ground melts, it can become water logged and a thick mud that cannot support the things that are on top of it. Another problem is carbon dioxide release. When the ground froze, a lot of carbon dioxide was trapped in it. When it melts, this carbon dioxide is released into the atmosphere.
So, what are zombie viruses? When the permafrost was made, the ground froze. Before it became cold enough to freeze, it was normal ground with normal vegetation and animal life living on it. The cycle of life existed here as it did everywhere else. Plants and animals died, fell to the ground, and were broken down by bacteria, worms, and the things that live in the soil. Their nutrients reentered the soil to make life possible for new plants and animals. And this is where zombie viruses come from. When the ground freezes, all of the rotting biomass and any bacteria and viruses that are them freeze as well.
Dying of hypothermia is not the same as being frozen to death. If you were able to freeze a person, they would die because they wouldn’t be able to pump the blood around their body. However, there is a field called cryogenics where people who have died are frozen so that they (theoretically) can be defrosted and brought back to life when medical science has advanced enough. Today, it is impossible to bring a frozen person back to life. When the people are frozen, it has to be done very quickly because if a person is frozen slowly, ice crystals form in the cells and the cell walls rupture. This happens to animals and plants that are caught in permafrost. Ice crystals form in their cells and ruptures the cell walls. However, this doesn’t happen to bacteria and viruses because they are too small for ice crystals to form. When they are frozen, they cease to function, but they are not dead. That means, if they are warmed up, they can continue to function.
Viruses were first found in the permafrost in 2014. A team from a French university found viruses that were 30,000 years old. In a later study, they found a virus that is 48,500 years old and they found 12 other types of virus as well. In 2016, the anthrax bacteria was released from the permafrost and killed 2649 reindeer in Siberia. It also sickened 36 people and killed a boy. Experts are worried about these viruses and bacteria being released for several reasons. The first is that they can wipe out animals that don’t have any immunity to a virus that hasn’t been around for millennia. The second is that some of these viruses could affect us as well. There is no real way to know what dangers are going to be released as the permafrost melts. Most of the viruses and bacteria won’t cause any problem for us at all, but some might. And this is what I learned today.
Image By Boris Radosavljevic – https://www.flickr.com/photos/139918543@N06/24532258070/, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=80427880
Sources
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10333728
https://www.mdpi.com/1999-4915/15/2/564
https://en.wikipedia.org/wiki/Permafrost
https://serc.carleton.edu/eet/permafrost/part_1.html
https://www.epa.gov/climate-indicators/climate-change-indicators-permafrost
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