We have no idea what lies frozen in the ice sheets and permafrost of the Arctic where temperatures are rising twice as fast as the rest of the world. Last year in 2020, as the world was reeling from COVID-19, temperatures in north eastern Siberia soared to 38 degrees Celsius, and the land surface temperature there spiked to 45 degrees Celsius! With the permafrost melting rapidly in the Arctic, not only is it releasing the stored carbon and other potent greenhouse gases such as methane, aggravating climate change, but is also triggering something else. Something equally sinister.
A large portion of the Arctic region is covered in permafrost. Photo: Public Domain
Several bacteria and viruses, some of them deadly, are laying dormant waiting to be resurrected from these frozen depths. While we humans are constantly in the company of countless bacteria and viruses around us, interacting with us, our bodies are also constantly adapting and evolving to resist these pathogens. But, permafrost – ground that stays frozen for long spans of time – provides ideal conditions for cryogenic preservation of microbes that are trapped within these layers of ice. That means, while they may lay dormant and inactive for as long as they stay frozen in the ice, even thousands, perhaps for millions of years, they will promptly come back to life upon thawing of the permafrost. What will happen if some of the bacteria or viruses, possibly new to us or haven’t interacted with humans for several hundreds or thousands of years, were to rise up from their icy slumber? Will they bring with them newer, deadlier infectious diseases? Ones that will shock our ill-prepared immune systems and wreck havoc?
The world got a bitter taste of such a reality in August 2016, in Yamal Peninsula in the Siberian tundra, when dormant anthrax from the frozen carcass of an infected reindeer that had been dead and buried in the permafrost for nearly 70 years, was released on account of a severe heatwave that hit the region that summer. The layers of permafrost which otherwise remained frozen through the year thawed and this unleashed the spores of hitherto frozen, deadly bacteria called Bacillus anthracis which causes the zoonotic disease, anthrax. These pathogens managed to enter the water and soil in the area, infecting over 2,000 reindeer, eventually moving on to humans. Over 20 people got infected with anthrax, and needed hospitalisation. Unfortunately, a 12-year-old boy succumbed to the disease.
Anthrax bacteria (green) being swallowed by an immune system cell. Photo: Zeiss Microscopy_Flickr
Melting of permafrost is not unusual. On an average, about 50 cm. of permafrost melts each summer in the Arctic Circle. This layer called the “active layer” that sits on top of the permafrost undergoes a cycle of melting and freezing annually in the northern hemisphere. This active layer of the permafrost measures up to 30 cm. to 1.5 m. in thickness, while the permafrost underneath could be as thick as 1,500 m. as seen in certain parts of Siberia. Permafrost is essentially any earth material such as soil, rocks, organic matter, minerals, etc. which remains frozen at or below zero degree Celsius for up to or more than two straight years. But, because regions in the Arctic Circle are getting warmer, the active layer is getting bigger and deeper, which means more and more parts of the permafrost that stayed frozen though the year are no longer permanently frozen. This trend of growing active layer was initially noticed in the 1990s. But, it is only within the last decade that parts of permafrost have begun to thaw for longer periods of time, and this is only accelerating.
General anatomy of the permafrost. Photo: Benjamin Jones/USGS/Public domain
With galloping global warming, older layers underneath are being exposed, thawing and melting, thanks to rising temperatures. And it is not just anthrax. Other known dangerous pathogens such as the small pox virus – considered to be “the deadliest disease in modern history” – and the bubonic plague bacteria also lie buried in the Siberian soil, dormant but possibly alive in the bodies of people who got infected in the past, succumbed and remain buried underground within all the permafrost. Researchers, in 1997, found fragments of RNA of the 1918 influenza virus in the corpses found in the Alaskan permafrost. In 2005, scientists at NASA were able to resuscitate the bacteria collected from layers of permafrost in Alaska that date back to the Pleistocene epoch (12,000-2.5 million years ago)! That was when the wooly mammoths were still around. In 2014, a study published in the Proceedings of the National Academy of Sciences revealed how scientists reactivated some “giant viruses” which were unearthed after 30,000 years of being stuck in the Siberian permafrost. Scientists can now revive even eight million-year-old bacterium lying dormant in the ice in Antarctica!
Makes you wonder what else lies in wait within these icy depths, ready to awaken.
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About the author: Purva Variyar is a conservationist, science communicator and conservation writer. She works with the Wildlife Conservation Trust and has previously worked with Sanctuary Nature Foundation and The Gerry Martin Project.
Disclaimer: The author is associated with Wildlife Conservation Trust. The views and opinions expressed in the article are her own and do not necessarily reflect the views and opinions of Wildlife Conservation Trust.
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