The Arctic – a crucial cold cap
Gilded in a vast, fragmented cover of reflective ice encircling the Arctic ocean, the Arctic proudly crowns the Earth as one of its two polar air conditioning units. At 5.5 million square miles, the Arctic matches in size its polar cousin Antarctica, politically engulfing vast swaths of Canada, Alaska, Russia, Greenland and Scandinavia. Unique among the Earth’s ecosystems, it hosts a symphony of over 21,000 recorded species, interacting with the vast biodynamic webs that sustain life in all its most extreme forms (1). Up until 12,000 years ago, herbivorous herds of wild megafauna roamed the grasslands of the Arctic tundra, grazing, while mesofauna scurried about and marine mammals glided through nearby waters, all participating in the subtle yet vast biochemical dance of nature.
Climate change and a novel suite of global stressors
Permafrost, a layer of frozen soil covering one quarter of the Northern hemisphere acting as a large freezer (storing carbon, mercury, and bacteria), is a core player in this chemical dance. This layer has been thawing at increasingly rapid rates as the Arctic has experienced exacerbated responses to global warming. September Arctic sea ice is receding at a rate of 13.1 percent per decade (2), as new melting records are being set (3). While temperatures have risen by 2.0 °C on land and 0.5 °C in oceans, Arctic temperatures have risen beyond 10 °C. Concurrently, biodiversity is shrinking as species face what scientists are now dubbing a “sixth mass extinction” (4).
Colorless captured carbon stays cool – the Pandora’s box of permafrost
While ice caps and glaciers usually reflect a large chunk of the sun’s incoming rays, staying cool. The albedo number is proportional to this fraction of incident solar energy that is reflected back into space rather than boomeranging back down to earth. Ocean albedo is about 6%, while sea ice albedo is one tenth that – melting white permafrost would make way to a darker, hotter ocean surface, further feeding into an already runaway feedforward heating cycle. Recent satellite observations of Greenland have already shown that albedo has dropped every summer month expect May over the past three decades (5), while modeling has further confirmed that western Arctic land warming trends during rapid sea ice loss are 3.5 times greater than 20th century trends (6).
Thawing permafrost releases vast amounts of trapped carbon and methane, warming the air. Permafrost soil currently stores an estimated 1,500 billion tons of carbon, almost twice that in the atmosphere, the microbial respiration of organic matter within which, as it thaws, releases this carbon as methane or carbon dioxide into the atmosphere (7). Soaking up the energy of incoming sunlight, these gases re-emit it back out in all directions – half of which returns to space and half of which heads back down to Earth, triggering the cycle all over again. In the end, the carbon cycle feedback loops of the melting permafrost could double the warming effects of tundra-released greenhouse gases (8), possibly contributing to up to 1.7 °C of warming by 2300.
Finally, an ultimate cocktail of additional threats loom large. Permafrost may bring back ancient, trapped pathogens and their associated diseases (9), alter fungal networks in ways we are only beginning to understand (10), and continue to incur infrastructural damage to landscapes in the form of landslides and draining lakes (11). And of course – we also don’t know what we still don’t know.
Arctic rewilding to enhance ecosystems and curb climate change
How can these ripple effects be curbed? In the Pleistocene era, spanning 2.6 million to 12,000 years ago – thirteen times longer than humans have been around – fossil records estimate that one square Arctic kilometer harbored 15 reindeer, 7.5 horses, 5 bison, and 1 mammoth, about the density of an African savanna game reserve, contributing to a sustainably cold and healthy Arctic ecosystem. In a process of megafaunal ecosystem engineering, reintroducing such large megafauna to our current Arctic landscapes would restore many aspects of this original Pleistocene era Arctic ecosystem for two core reasons (12,13).
First, changes in the vegetation would increase the albedo effect and help sequester carbon. By trampling and eating them, large megafauna thwart the growth of shrubs and trees, allowing rapidly growing grasslands to flourish – picture elephants pulling up shrubs and knocking down trees as a present-day equivalent in the African savanna. By virtue of a more uniform surface, these grasslands would increase the albedo effect, while also, thanks to their deep roots shown to serve as greater carbon sinks than forests, capturing large stores of carbon (14).
Second, changes in the soil and overlying snowpack would make it colder and decrease carbon emissions. Removing shrubs and trees and compacting the snow under their weight, mammoth reintroduction would minimize the buildup of snow among these while increasing snow density, decreasing the insulation of permafrost layers from cold Arctic air – allowing all layers to stay colder longer. Permafrost temperature is accordingly estimated to remain below -4 °C on average after increasing herbivore population density. Finally, in parallel, condensed soils would have lower soil moisture, increasing carbon dioxide emissions (15).
Rewilding the Arctic – a creative solution in the context of the current conservation landscape
Why rewild the Arctic rather than other regions? First defined academically in 1998 by American conservation biologists (16), rewilding has successfully been implemented as an environmental preservation strategy in a variety of forms in recent decades (17). The reintroduction in the 1950s of the predatory wolf into Yellowstone National Park allowed cottonwood and aspen to flourish by reducing elk over-grazing and restored populations of smaller animals by minimizing coyote numbers. Since, reintroducing the beaver in the United Kingdom and Netherlands has helped regulate water, prevent flooding, and foster a thriving habitat for smaller animals, while, most recently, the charity Rewilding Europe has been successfully restoring one million hectares of Europe to wilderness (18). Incurring vast interconnected socioecological benefits, rewilding has covered an array of initiatives, of which Arctic rewilding is a key strategy of many.
Why rewild the Arctic instead of investing in other initiatives? In contrast to the many ongoing projects to minimize the albedo effect and carbon release, including geoengineering schemes aimed at painting trees a reflective white, rewilding tips the sustainability scale for its organic, scalable nature. The feedforward cycles inherent to carbon release and temperature changes are insufficiently reflected in policies, and climate commitments continue to fall short of the audacious yet necessary goals set forth by the Paris Agreement. Scalable (19), Arctic rewilding specifically addresses this nonlinear dynamic nature of climate change (20).
Today, imminent threat requires radical conservation strategies, and the time is ripe to usher in a fresh, scalable, and wild conservation agenda: by rewilding the Arctic.
- Arctic Council – Safeguarding Arctic biodiversity [Internet]. [cited 2021 Jul 22]. Available from: https://arctic-council.org/en/explore/topics/biodiversity/
- Arctic Sea Ice Minimum | Vital Signs – Climate Change: Vital Signs of the Planet [Internet]. [cited 2021 Jul 19]. Available from: https://climate.nasa.gov/vital-signs/arctic-sea-ice/
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- Riihelä A, King MD, Anttila K. The surface albedo of the Greenland Ice Sheet between 1982 and 2015 from the CLARA-A2 dataset and its relationship to the ice sheet’s surface mass balance. Cryosphere. 2019;
- Lawrence DM, Slater AG, Tomas RA, Holland MM, Deser C. Accelerated Arctic land warming and permafrost degradation during rapid sea ice loss. Geophys Res Lett. 2008;
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- Turetsky MR, Abbott BW, Jones MC, Walter Anthony K, Olefeldt D, Schuur EAG, et al. Permafrost collapse is accelerating carbon release. Nature. 2019.
- Brouillette M. How microbes in permafrost could trigger a massive carbon bomb. Nature. 2021.
- Schütte UME, Henning JA, Ye Y, Bowling A, Ford J, Genet H, et al. Effect of permafrost thaw on plant and soil fungal community in a boreal forest: Does fungal community change mediate plant productivity response? J Ecol. 2019;
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- Lawrence DM, Koven CD, Swenson SC, Riley WJ, Slater AG. Permafrost thaw and resulting soil moisture changes regulate projected high-latitude CO2 and CH4 emissions. Environ Res Lett. 2015;
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