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Walking on Thin Ice – Growing Concern of Public Health as Ice Holding Back Diseases Melts Rapidly

Arctic Ribbon Seal. Image Credit: UC Davis

As global warming melts frozen ground all over the world, the thawing ice releases greenhouse gases, and, more importantly, diseases which have remained dormant for thousands of years. Climate Change is rapidly thawing Arctic permafrost, permanently frozen ground which has remained locked beneath the surface for thousands of years. As temperatures rise, this frozen soil is beginning to release large amounts of greenhouse gases, ancient organic material, long-frozen animal remains, and even dormant microbes and viruses. Scientists are increasingly studying whether thawing permafrost could revive ancient pathogens, exposing humans and wildlife to diseases buried for centuries. This creates a continuous, destructive cycle: thawing ice releases massive amounts of greenhouse gases, which melt more ice, releasing more and more greenhouse gases. Researchers agree that thawing permafrost is a real and growing environmental and public health concern, not only from the massive amounts of greenhouse gases suddenly being released into the atmosphere, but also from the diseases which are being reawakened as ice thaws.

Permafrost is ground which has remained consistently frozen for at least two consecutive years^[¹^,²^]. Despite this definition, most permafrost on Earth today has stayed frozen for thousands or even hundreds of thousands of years^[³^]. Permafrost covers enormous portions of Alaska, Canada, Greenland, Siberia, and the Arctic tundra, making up much of these countries’ landscapes^[⁴^]. Permafrost layers contain ancient plant material, archaic animal remains, prehistoric microbes, and enormous quantities of greenhouse gases, all preserved in frozen conditions since before prehistoric times. Climate change is causing these regions to thaw however. The Arctic is warming four times faster than the rest of the planet in many areas, a phenomenon known as Arctic amplification^[⁵^]. As global temperatures rise, they cause permafrost to thaw at rapid rates all over the Arctic and world^[⁶^]. This quick thawing creates several severe environmental dangers at the same time.

As glaciers melt, they release greenhouse gases and dormant, potentially deadly diseases. Image Credit: The Guardian

One of the largest concerns is the release of greenhouse gasses. Permafrost contains massive amounts of frozen, organic carbon harvested from dead plants and animals which never completely decomposed in the cold environments they lived in. When permafrost thaws, microbes quickly begin breaking down this organic matter. This releases carbon dioxide and methane into the atmosphere^[⁷^]. Methane is particularly concerning due to its ability to trap far more heat than carbon dioxide^[⁸^]. Higher levels of methane in the atmosphere trap more heat than carbon dioxide can. While small amounts of carbon and methane being released into the atmosphere do not have particularly concerning effects, the amount of carbon and methane stored in permafrost is not small. Scientists estimate that Arctic permafrost alone stores 1,400 to 1,600 billion tons of carbon^[⁹^]. In context, this is nearly twice as much carbon already existing in Earth’s atmosphere. This creates a dangerous feedback loop: Warming causes permafrost thaw, which releases more greenhouse gases, which causes more warming. More warming accelerates further thaw, and the cycle continues. Unfortunately, greenhouse gases aren’t the biggest concern.

As frozen ground melts, ancient biological material re-emerges after being sealed away for millenia. Researchers have discovered remarkably well-preserved mammoths, ancient wolves, prehistoric plants, bacteria, fungi, and viruses inside thawing Arctic permafrost. Some microorganisms can remain dormant in frozen conditions for extremely long periods of time^[¹⁰^,¹¹^]. When the ice containing them thaws, they re-activate. In laboratory settings, scientists have successfully revived dangerous ancient viruses recovered from Siberian permafrost which had remained frozen for tens of thousands of years^[¹²^]. For instance, a 30,000 year old giant virus, Pithovirus Sibericum, was revived by French researchers in 2014 under controlled laboratory conditions^[¹²^]. Scientists additionally revived other ancient viruses affecting amoebas from permafrost samples dating back nearly 50,000 years^[¹²^]. Researchers performed these studies under controlled conditions to understand microbial survival in extreme environments. However, scientists worry that thawing permafrost could expose modern ecosystems and wildlife to ancient pathogens and diseases that humans and animals in the modern day have little resistance against. In fact, these fears were realized in a diluted sense when melting permafrost in Siberia sparked an epidemic in 2016. An intense Arctic heat wave had thawed permafrost containing a decades-old reindeer carcass infected with anthrax bacteria. The thawing released the bacteria into the surrounding environment. This caused an intense anthrax outbreak, which infected countless people, hospitalized children, and killed thousands of reindeer. This served as an example of how diseases can be preserved in frozen environments before emerging when permafrost thaws. Researchers are most concerned because climate change is increasing thaw and erosion, exposing more and more secretly dangerous ice. For instance, climate change is increasing Arctic wildfires, erosion, flooding, and ground collapse. This exposes deeper layers of previously frozen material. Thawing permafrost is also physically destabilizing Arctic landscapes. As massive regions thaw, areas lose structural support originally upheld by the frozen ground, collapsing roads, sinking buildings, damaging pipelines and causing landslides and coastal erosion^[¹³^]. Some Arctic communities face severe infrastructure damage already because many of their buildings or roads relied on the stability of permafrost.

Scientists are increasingly viewing permafrost thaw as one of the most important long-term climate tipping points. Though we do not predict an imminent global pandemic emerging from the Arctic, there are serious concerns associated with this hidden consequence of climate change. As climate change causes accelerated Arctic warming, ecosystem distribution, greenhouse gas release, ancient pathogen exposures, and infrastructure collapse, this overlooked effect of climate change is causing more and more problems all over the world as temperatures continue to rise.