We’ve been raised to believe that we’re safe from the world’s past illnesses. Such dangers as smallpox and the bubonic plague are a relic of a bygone era. Well, “Not so fast,” say researchers studying permafrost in Siberia.
According to Dr. Jean-Michel Claverie of France’s Aix-Marseille University, viruses cannot be removed from the planet. In fact, he and other researchers have discovered dormant bacteria and viruses lurking beneath the surface of the Siberian permafrost. As that permafrost melts, these particles could get resurrected and released.

What is Permafrost?

Permafrost is a soil layer just under the land surface that is permanently frozen (well, for now, but we’ll get to that). Soil must remain below 0 degrees Celsius (32 degrees F) for two or more years to be considered permafrost. It only forms in locations with average temperatures below 0 degrees Celsius.
Permafrost occurs worldwide, mainly at high latitudes. But it is also found at high elevations in lower latitudes. This lower latitude permafrost is called alpine or mountainous permafrost.
Permafrost covers around 20% of the world’s land surface and 24% of the land in the Northern Hemisphere. Permafrost can remain frozen for millions of years and can be from less than one meter up to 5,000 meters thick.
The top layer of permafrost, called the active layer, melts regularly. The permafrost beneath this active layer remains frozen when the active layer thaws. This second layer grows downward each winter. It takes thousands of years for permafrost to reach hundreds of feet of thickness.
Despite its advanced age, much permafrost is usually near its melting point. Global climate change is a threat to permafrost. As temperatures rise, permafrost begins to thaw. In addition, increasing snow melt flows speed up erosion. This thawing and faster erosion can free things that have been trapped in the permafrost for thousands to millions of years.

A Time Bomb

Bacteria can remain alive at -20 degrees Celsius. Their revival could be very fast, if not immediate, after being thawed. Frozen permafrost is excellent for keeping bacteria and viruses alive for a very long time. Because of the cold, dark, oxygen-free conditions, it is great at preserving things.
So, it’s basically a massive freezer, one that global climate change is defrosting. The Arctic, where permafrost is widespread, is warming 2-3 times faster than the rest of the planet. Because of this warming, Arctic sea ice is also melting, breaking down barriers to land that used to be unreachable. This opens up drilling and mining opportunities in unplumbed wells of resources. Where there’s a chance to make a profit, humans will take advantage.
Unfortunately, this means ancient permafrost layers spared by the excess heat are likely to be uncovered. Ancient bacteria or viruses, once thought to have been destroyed, could be released. Dr. Richard Spencer, an environmental scientist and oceanographer at Florida State University, calls the permafrost “A ticking time bomb”.

Spanish Flu

In 1951, a group of researchers trekked to the Alaskan tundra to unearth the mass graves of Spanish flu victims from 1918. They took lung samples and preserved them.
In 1995, scientific advances made it possible to start getting information from the flu virus that was still in the lung samples. In 2005, researchers figured out the full makeup of one piece of the virus’s unique structure. This means that a nearly 100-year-old virus buried beneath permafrost for over thirty years and preserved in a laboratory for an additional forty-four was still in good enough shape to figure out its structure. Talk about persistence.


Since the 1990s, a Siberian research group has been testing the remains of 19th-century smallpox victims. The bodies are so well-preserved that researchers can still see smallpox sores on the skin.
While they haven’t found the full smallpox virus, they have found fragments of smallpox. This suggests that smallpox could be hanging out in the permafrost, primed for an 1800s revival.

Other Viruses

 In 2014, another team of researchers resurrected two viruses that had been stuck 100 feet underground in the Siberian permafrost for 30,000 years.
Both these viruses, Pithovirus sibericum and Mollivirus sibericum, became infectious quickly. They violently killed amoebas in their Petri dish (the amoebas exploded). Luckily for us, these viruses are only dangerous to amoebas.
However, other viruses, ones that affect humans, could be on their way to the surface. The team has found evidence of highly infectious bacteria. They have also found fragments that seem to have come from viruses like herpes. They recommend that we keep stockpiles of vaccines even if we think the diseases they prevent are gone just in case.

The Anthrax Incident

In August of 2016, twenty-three people on the Yamal Peninsula of Siberia were infected with anthrax. A 12-year-old boy died.
75 years earlier, anthrax infected and killed more than 1 million reindeer. Their bodies were buried just under the surface and covered over the years with more layers of soil. In July of 2016, a heat wave caused those soil layers, which had become permafrost, to thaw. Anthrax emerged and entered the water, soil, and food supply, infecting modern reindeer and humans alike.

Other Bacteria

 In 2005, NASA researchers revived a bacterium frozen in an Alaskan pond since the Pleistocene Era (32,000 years ago, the time of the woolly mammoths). They didn’t even have to do anything special. Once the water thawed, the bacteria started swimming.
In 2007, a separate research group managed to resurrect a 100,000-year-old bacterium and an 8-million-year-old bacterium from a glacier in Antarctica. More frightening than these bacteria is a 30,000-year-old bacterium locked in permafrost that was resistant to three of our current antibiotics.

The Climate Change Loop

Not only could melting permafrost release dangerous pathogens, but it is known to release greenhouse gases. Greenhouse gases trap heat in the Earth’s atmosphere, causing global warming. Permafrost holds around 1500 billion tons of carbon, twice as much as is in our atmosphere today.
In the event of a thaw, most of that carbon would come out as carbon dioxide, a dangerous greenhouse gas. However, some would come out as methane. Methane is thirty times better at trapping heat than carbon dioxide. Such releases would lead to more intense warming. This can cause more permafrost to melt and release more greenhouse gases.
And potentially, more diseases.

But We Have Antibiotics

Over the years, we have danced with bacteria and viruses in an evolutionary arms race. Viruses and bacteria infect us, we develop resistance, and they get better at infecting us. Then, in the 1920s, Alexander Fleming changed the game by discovering penicillin. After that, the age of antibiotic development begun.
The tables were turned.
Now, the viruses and bacteria had to develop resistance. However, it turns out that they were somewhat prepared for this. 99.9% of our antibiotics are naturally-occurring. So, bacteria and viruses were building up resistance to them before we even discovered them.
Bacteria found in crystals buried in caves for 4 million years are resistant to 70% of the antibiotics we currently use. Much like the viruses described above, these bacteria don’t infect humans.
Even so, other bacteria and viruses that infect humans could be brewing beneath the surface, having already evolved resistance to most of our arsenal. In addition, we have been evolving and thriving in the absence of these potential pathogens for millennia.
This means that we haven’t been working to develop resistance. Our immune systems will be woefully unprepared if ancient diseases resurrect from the permafrost.

Should We Really Worry?

Dr. Claverie, Dr. Spencer, and others believe the melting permafrost is a source of dangerous diseases from the past.
However, Dr. Curtis Suttle, a marine virologist at the University of British Columbia, disagrees. He is confident that there won’t be enough bacteria and they won’t travel far enough to present a public health risk. He is more concerned with other effects of climate change, including rising sea level displacing millions of people.
Still others believe that we can’t know much about the probabilities of zombie bacteria and their effects. So our efforts are better focused on the threats we can quantify.
What do you think?

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