Can we stop Canada’s thawing permafrost from releasing huge volumes of greenhouse gases? The solution could be wild

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In Eastern Siberia, above the Arctic Circle, Russian researchers are attempting to bring back landscapes not seen since mammoths roamed the Earth. At Pleistocene Park, they’ve fenced off 16 square kilometres and introduced bison, muskox, horses and other herbivores. They hope the animals’ grazing will transform the landscape into grassland, which will cool the underlying permafrost.

Uninitiated visitors might mistake the Arctic for one of Earth’s last great unspoiled wildernesses. Nikita Zimov, Pleistocene Park’s director, regards it as an ecosystem degraded by hunters who arrived 14,500 years ago. They quickly wiped out mammoths and other large animals, he says, resulting in the disappearance of expansive grasslands they once maintained.

“In the Russian Arctic you don’t really see much wildlife – it’s a sad situation,” he said. “We’ve started to bring animals in, and we are supporting them.”

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Established in 1996, Pleistocene Park attracted greater interest during the last decade as scientists began studying “permafrost carbon feedback.” Permafrost contains a motherlode of organic matter that will decompose if unfrozen, releasing carbon dioxide and methane into the atmosphere. The Intergovernmental Panel on Climate Change expects widespread permafrost thaw this century as temperatures rise. Many researchers fear that could produce a calamitous cycle, in which releases from permafrost beget more warming which begets still more thawing, effectively turbocharging climate change.

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Ted Schuur, a professor at Northern Arizona University’s Center for Ecosystem Sciences and Society, said that in well-studied regions like Alaska, there’s evidence thawing permafrost is already releasing greenhouse gases. Although he acknowledged there’s less evidence from other regions. “We should act as a society even in the face of uncertainty,” he said, “as this issue is unlikely to go away.” Canada has declared that it must act decisively to limit permafrost thaw.

But act how, precisely?

There are few cogent, targeted options. At a conference earlier this year organized by the PCF Action Group, a new collaboration among scientists, permafrost engineers, entrepreneurs, participants focused on massive “geoengineering” schemes intended to affect Earth’s entire climate. Many of the ambitious proposals read like science fiction film scripts.

But the approach taken at Pleistocene Park, which has been dubbed “megafaunal ecological engineering,” is among the more mature: Mr. Zimov’s experiment, after all, has been running for a quarter century.

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Grassland protects permafrost by changing the landscape’s albedo – that is, its ability to reflect sunlight. Grassland’s albedo is far higher than tundra dominated by moss and shrubs, or taiga forest, particularly when it’s covered by snow and ice. Grazing animals also trample snow in winter, reducing its insulating effect and thus chilling the ground underneath.

A 2019 study by the Environmental Change Institute at the University of Oxford suggests this approach works: mean soil temperatures in the park’s grazed areas were 2.2 degrees Celsius cooler than in a control area. (Mr. Zimov co-authored the study.) John Moore, a professor at the University of Lapland in Finland who specializes in climate research and geoengineering, said that finding demonstrates “a pretty significant improvement in the long-term stability of the permafrost.”

Different grazing patterns have been shown to change land albedo elsewhere, he added. Norwegian reindeer herders use their side of the fenced border between Norway and Finland primarily in winter; in summer their side is dominated by white lichens that reflect sunlight. Finland’s much larger reindeer herds graze on the other side of the fence in summertime, eating the lichens and promoting a greener landscape.

But it’s unclear how megafaunal engineering could be scaled up sufficiently to protect large swaths of Arctic permafrost.

Pleistocene Park’s evolution has been painfully slow. Mr. Zimov’s father, Sergey Zimov, began his first grazing experiments in 1988 but the Soviet Union’s collapse interrupted them. In 1996, he resumed the work, establishing Pleistocene Park. It’s now home to roughly 40 Yakutian horses, a dozen bison, three musk ox, 20 reindeer, fewer than 15 moose, 18 sheep, eight yak and 15 cattle – a curious menagerie, but hardly a sprawling new biome.

Of 2,000 hectares in the fenced area, Mr. Zimov estimates that only 100 hectares are halfway through their transition to grassland; the rest of the park is at earlier stages.

“I don’t think there are any places in the park where we’re able to say, ‘We are done here,’” he said. “But I see that many places are in transition. Overall, the productivity is increasing.”

One reason for the painstaking progress was that the Zimov family funded the project’s early development almost entirely. More recently, the project has begun to win sponsors. But the 2019 paper acknowledged that a rigorous experiment would require thousands of animals – an expensive proposition. Introducing three herds of 1,000 animals each would cost an estimated US$114 million.

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Herds can’t be conjured out of thin air. The muskox and bison largely look after themselves, Mr. Zimov said, but researchers must provide forage for other species during the harsh winters. Mr. Zimov plans further interventions such as introducing predators to encourage “landscapes of fear,” which would change grazing patterns. (Left unmolested, many herbivores don’t move around much in winter, meaning they won’t trample enough snow.) Mr. Zimov has even broached the possibility of reintroducing long-extinct creatures such as mammoths and cave lions, though the 2019 paper acknowledged that neither is “available in the near future.”

Such ongoing and planned intervention highlights the reality that Pleistocene Park is not self-sustaining. It’s not clear it will ever be.

Mr. Zimov himself was uncertain whether the concept could be replicated elsewhere. Like Russia, he said, Canada has large swaths of unpopulated territory, and lots of permafrost. But the geography is different: Much of Canada’s north is rocky and contains less carbon-risk permafrost. More research would be needed, he said, to determine whether it could work here.

“Even though everybody loves the idea of rewilding the Arctic, reversing the changes that humans caused by hunting mammoths and other large fauna to extinction,” Dr. Moore observed, “in practice it’s a little more difficult.”

Indeed, the risks of geoengineering are high.

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Damon Matthews, a professor of climate science and sustainability at Concordia University, told conference attendees about historical interventions in ecosystems such as an attempt in the late 19th century to protect Hawaii’s sugarcane industry from rat infestation. Since rats were an invasive species with no natural predators on the islands, mongoose were introduced. It was belatedly recognized that rats are nocturnal and mongoose hunt during the day, so the mongoose hunted and destroyed other species such as sea turtles instead.

“The history of biocontrol, from mongooses in Hawaii, to cane toads in Australia, to African land snails, show that attempts to intervene in complex ecological systems have led to worse outcomes,” Dr. Matthews said. “Geoengineering would very likely increase, rather than decrease, net climate damages. What we need to do is get on with decarbonization itself.”

But today’s Arctic, Mr. Zimov contends, is itself the product of large-scale human intervention. The grasslands he’s attempting to restore were “the most productive ecosystems which have ever been on our planet,” he said. “We destroyed it. And I think it’s now a possibility to bring it back.”

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