A team of European researchers digging through Siberian permafrost discovered 13 types of prehistoric viruses that had been dormant and reactivated them.
This type of virus is called "zombie viruses", and includes viruses that have been "dormant" or inactive and frozen in ice for tens of thousands of years.
As temperatures rise due to climate changes, more microbes that modern humans have not encountered will surface.
The new study, the results of which were published in the journal "Viruses", raises a number of questions:
Are zombie viruses harmful to humans?
No human was harmed in the new study, according to a report on WebMed.
The viruses observed here were only capable of infecting amoebae.
But viruses that can infect humans already exist in environments such as permafrost, which means that the probability of discovering an unknown virus one day and resulting in another pandemic is not necessarily zero.
"There is an objective risk, and it is increasing," says Dr. Jean-Michel Claverie, the study's principal investigator and professor emeritus of genomics and bioinformatics at Aix-Marseille University in France.
Based on Claverie and his team's findings, viruses that infect humans and animals can survive deep in permafrost for long periods of time.
Are zombie viruses contagious?
"From our research, we can conclude that other viruses in permafrost are likely still infectious," says Clavery.
Is there a high risk of zombie virus?
The chance of something catastrophic happening is slim, as the viruses that emerge in the thaw will quickly degrade once exposed to heat, ultraviolet light and oxygen, Claverie says.
And in places like Siberia where permafrost exists, people generally don't exist.
So, some of the fears inspired by science fiction are unfounded.
But if more people start migrating towards areas where these microbes appear, the chances of the virus successfully infecting the host may be greater.
What if the next deadly virus came from the Arctic permafrost?
Will we be ready?
Dr Adrian Liston, an immunologist and senior group leader at the Babraham Institute, a life sciences research institute at the University of Cambridge in the UK, says:
On the one hand, we will not have pre-existing immunity to these viruses, so the initial ability to fight infection is low.
On the other hand, the zombie virus has not been adapted to infect humans in modern times, so the chance of it succeeding in infection is very low.
"This is something that a lot of people don't understand," Liston, who was not involved in the study, explains. "Today's viruses and other infectious microbes are infectious only because they are present today. They have evolved to function within our modern immune systems."
Examples include the smallpox virus and tuberculosis bacteria, which severely affected human evolution when they entered our species.
"There are many microbes that are beneficial to humans," says Liston. "But in general, these are microbes that have evolved over millions of years to work in harmony with our bodies, like our microbiome."
Some random frozen microbes are unlikely to affect us directly, Liston says, but if they do, they're likely to be bad.
The ever increasing impacts of climate change
If there is anything that zombie viruses can remind us of, it is the ever increasing impacts of climate change on our lives and our planet in the near future.
“The most important message,” says Liston, “is that climate change will create unexpected problems. It's not just changes in weather, climate phenomena, and sea level rise. A whole series of secondary problems will be created. New infections, some of which could turn into a pandemic, will almost certainly be created.” will happen because of climate change."