Permafrost releases ghosts of the past

Do you remember the 1969 French film titled Hibernatus? The title character-Paul Fournier (played by Bernard Alane)-is awakened after more than 50 years of being frozen in the Greenland ice, and his appearance causes many amusing adventures, but also unexpected problems. It only took half a century of hibernation, and already a newcomer from the past has caused quite a stir. The situation is no different with other frozen animals trapped in the ice of Alaska or Siberia. The permafrost stores not only mammoths, but also many secrets that, when released after tens, hundreds, and sometimes even millions of years, can stir up as much trouble as the titular Hibernatus.

Permafrost, or permafrost

Permafrost (sometimes called permafrost in English) is defined as ground or bottom sediment that remains frozen for a period of not less than 2 years. It is a remnant (relic) of the glaciation that covered much of the Northern Hemisphere’s land areas in the Pleistocene. It currently covers about 11 percent of the Earth’s surface and 15 percent of the Northern Hemisphere, covering an area, according to various sources, of 18 to 23 million square ^kilometers [1-2, NSIDC, or National Snow and Ice Data Center]. Of this, about 80 percent is in Alaska, most of northern Canada and more than half of Siberia. It is also spotty in the Scandinavian Mountains and Greenland. Discontinuous permafrost is also found in high mountain regions, mainly in Tibet and the Alps.

Not everyone knows that permafrost has also been discovered in northeastern Poland, near Suwałki (after all, the cold pole!). In 2010. Geologists from the National Geological Institute at a depth of more than 350 meters have come across the ceiling of permafrost 13,000 years ago [3]. This is a remnant of permafrost from the period of the last glaciation, which has survived to our time thanks to specific geological conditions, the so-called Suwałki geothermal-hydrogeochemical anomaly.

According to data from the U.S. National Snow and Ice Data Center (NSIDC), the thickness of permafrost varies from less than 1m to more than 1km. Most of this cover has survived in the Arctic for 800,000 to 1 million years, but climate change could significantly change this picture.

Permafrost not so eternal

Numerous data prove that as the planet warms, permafrost is thawing at an accelerating rate; especially since the Arctic regions are experiencing temperature increases about 2-3 times faster than the global average. Over the decade between 2007 and 2016, the rate of permafrost temperature increase ranged from 0.39 ± 0.15°C to 0.20 ± 0.10°C [4], and long-term measurements indicate its record high temperatures at depths of ∼10-20 meters.

Even if the increase in global air temperature does not exceed 2°C by 2100, permafrost will continue to degrade over a significant area. Some estimates indicate that up to two-thirds of the near-surface permafrost could melt by that year. It’s not hard to guess that this process will not leave the Earth’s ecosystem unaffected.

Trapped in ice, or miracle-whirls

For millennia, as a result of natural processes, various incidents or intentional storage, permafrost has accumulated a variety of matter. It traps huge amounts of greenhouse gases, anthropogenic pollutants, including nuclear waste, heavy metals, persistent organic pollutants and other hazardous substances, as well as microorganisms – bacteria and viruses. And as long as they remain frozen, they are inactive and relatively harmless, because no physical or biological processes take place in them. The problem begins when thawing releases them into the environment, and with them known and unknown dangers.

The main issue raised in the media and scientific literature in the context of permafrost melting is the release of greenhouse gases. It is estimated that 1.46 to 1.70 billion tons of carbon, including methane and carbon dioxide, are accumulated in the ice of Arctic areas [6, 7]. The permafrost region contains 33 percent of the global pool of carbon stored on just 15 percent of the world’s total land area.

Thawing permafrost releases the greenhouse gases carbon dioxide and methane into the atmosphere, although key elements of this process, such as the amount, specific sources and timing of the release, remain unclear and are still the subject of extensive discussion and analysis. Currently available models predict a variety of scenarios, ranging from those that indicate a gradual release of 5 to 15 percent of carbon stocks over decades and centuries to those that indicate a sharp jump in the amount of carbon released from permafrost into the atmosphere over the next 100 years [7]. Regardless of the severity of this phenomenon, the increase in_CO2 and _CH4 emissions from permafrost areas is a fact.

Free the atom? Heavy metals and DDT too, unfortunately

The release of greenhouse gases is a big, but not the only problem resulting from thawing permafrost. As a 2021 review of the issue, published in Nature Climate Change [8], indicates, since the beginning of the industrial era, permafrost has accumulated heavy metals, soot and other byproducts of fossil fuel combustion transported long distances by air. Over the past 80 years, the array of anthropogenic pollutants has expanded to include other dangerous chemicals, such as the insecticide DDT (dichlorodiphenyltrichloroethane), hexachlorohexane (HCH) and polychlorinated biphenyls (PCBs), commonly used in coolants.

These substances were banned in the early 21st century, but the Arctic permafrost continues to be a reservoir for them. These and other persistent organic pollutants (POPs), which have entered the Arctic by air and accumulated in the permafrost in significant quantities over time, can negatively affect ecosystem stability, human and animal health when released into the environment.

The release of hazardous substances is reflected in trophic networks. The presence of long-discontinued POPs is found in the tissues of invertebrates, seabirds, fish and mammals, confirming the penetration and transfer of these chemicals to all trophic levels. In Arctic plants, concentrations of PCBs and organochlorine pesticides are now higher than in local soils. Trophic networks will therefore be an important vector for the spread of released substances.

The Arctic hides natural deposits of metals that have been mined for decades. Mining activity has left waste rich in toxic heavy metals such as mercury, arsenic and nickel. It is estimated that mercury alone is stored in the permafrost at around 800,000 tons, and current warming trends could increase its emissions by up to 200 percent by 2300.

The Arctic’s soil and permafrost show high levels of radioactive waste, accumulated from nuclear tests conducted here since the 1950s. In the 1970s. Detonations carried out by the Soviet Union in the New Earth archipelago released 265 Mt of nuclear energy. In the Barents and Kara Seas, the Russians sank more than 100 decommissioned nuclear-powered submarines, releasing radioactive plutonium and cesium, detected today in bottom sediments and ice caps, as well as in plants and soil beneath glaciers. Scientists estimate that radiation levels in the Arctic could remain harmful until 2500.

Zombies made of ice

If greenhouse gases and radioactive materials may be a bit of an abstraction for some, then perhaps viruses will no longer be. In truth, they can’t be seen by the naked eye either, but the consequences of their appearance can be truly spectacular, as humanity has seen many times in its history.

Indeed, numerous microbial threats, such as bacteria and viruses, also lurk in the Arctic permafrost. The low temperature, lack of light and oxygen create conditions ideal for the preservation of biological material, allowing microorganisms (called Matuzalem microorganisms by scientists because of their longevity) to survive for thousands or even millions of years. In 2014. scientists isolated live viruses from the Siberian permafrost and showed that even though they had been preserved for thousands of years, they still had the ability to infect single-celled organisms.

Granted, they only attacked amoebae and posed no threat to humans, but that doesn’t mean that other viruses – now trapped in permafrost – can’t cause disease in humans. Further research, published in 2022 [9, 10], revealed the existence of several different strains of viruses in the Siberian ice that maintained the ability to infect cultured cells. One of the samples had more than 48,000. years. A permafrost survey of Sweden’s Stordalen Mire found more than 1,900 viruses, 58 percent of which were still active [11].

Scientists believe that in the deepest layers of permafrost there may be preserved viruses that are up to 1 million years old, much older than our species, which is believed to have emerged around 300,000. years ago. This means that the human immune system has never come into contact with many of them. The scenario in which an unknown virus that once infected a Neanderthal becomes a threat to modern humans, while unlikely, is no longer a complete abstraction.

Not just humans and mammoths

Media reports on finds in the melting permafrost focus mainly on large, spectacular objects, such as the relatively numerous mammoth remains discovered, or the ice man Ötzi, found in 1991 on the Alpine glacier Val Senales on the border between Tyrol and Italy, whose age was determined to be five and a half thousand years old. As Maja Lunde writes in her latest book:

Ötzi held the title of Europe’s oldest mummy for many years, but that was before the twenty-first century, before the time of the great melt, before the truly age-old ice deposits were exposed (…) [12]. The author may enthrall some with her visionary spirit and irritate others with her naiveté, but some of her visions seem increasingly likely. It may not be long before the melting permafrost unleashes even more astonishing ghosts of the past.

In the article, I used, among others. z:

[1] Lindgren A., Hugelius G., Kuhry P., et al. (2016). GIS-based maps and area estimates of Northern Hemisphere permafrost extent during the last glacial maximum: LGM permafrost. Permafr. Periglac. Process. , 27 6-16

[2] Overduin P P., Deimling S. von T., Miesner F., et al. (2019). Submarine permafrost map in the Arctic modeled using 1-D transient heat flux (SuPerMAP). J. Geophys. Res. Oceans, 124, 3490-507

[3] Szewczyk J., Frozen Time. https://web.archive.org/web/20190501153606/https:/www.pgi.gov.pl/kopalnia-wiedzy/128-energia-geotermalna/594-zamroiony-czas.html

[4] Biskaborn B.K., Smith S.L., Noetzli J. et al. (2019). Permafrost is warming at a global scale. Nat Commun, 10, 264. https://doi.org/10.1038/s41467-018-08240-4

[6] Miner K.R., Turetsky M.R., Malina E. et al. (2022)Permafrost carbon emissions in a changing Arctic. Nat Rev Earth Environ 3, 55-67. https://doi.org/10.1038/s43017-021-00230-3

[7] Schuur E.A.G., Abbott B.W., Commane R., et al. (2022). Permafrost and Climate Change: Carbon Cycle Feedbacks From the Warming Arctic. Annual Review of Environment and Resources, 47:343-371. https://doi.org/10.1146/annurev-environ-012220-011847

[8] Miner K.R., D’Andrilli J., Mackelprang R. et al. (2021). Emergent biogeochemical risks from Arctic permafrost degradation. Nat. Clim. Chang. 11, 809-819. https://doi.org/10.1038/s41558-021-01162-y

[9] Rigou S., Christo-Foroux E., Santini S., et al. (2022). Metagenomic survey of the microbiome of ancient Siberian permafrost and modern Kamchatkan cryosols. microLife, 3, uqac003. https://doi.org/10.1093/femsml/uqac003

[10] Rigou S., Santini S., Abergel C., et al. (2022). Past and present giant viruses diversity explored through permafrost metagenomics. Nat Commun, 13, 5853. https://doi.org/10.1038/s41467-022-33633-x

[11] Emerson J.B., Roux S., Brum J.R., et al. (2018). Host-linked soil viral ecology along a permafrost thaw gradient. Nat Microbiol 3, 870-880. https://doi.org/10.1038/s41564-018-0190-y

[12] Lunde M. Dream of a Tree. Literary Publishers, 2024