MOSCOW (BLOOMBERG) - Emissions of greenhouse gases from Russia's thawing Arctic permafrost represent a giant climate threat for the planet.
A pair of Russian scientists say the solution may lie in grazing a huge number of animals there, and possibly even a mammoth one - the woolly sort.
Dr Nikita Zimov and his geophysicist father Sergey have a plan to return the Arctic ecosystem to the way it looked some 14,000 years ago at their Pleistocene Park project in Siberia.
They've also teamed up with a US "de-extinction" company, Colossal Laboratories and Biosciences, that's working to breed woolly mammoth.
"We are restoring highly productive pasture ecosystems in the Arctic, similar to those that existed here before the arrival of prehistoric man," said Nikita, 38, the park's director.
"This ecosystem was called the Mammoth Steppe and dozens of large herbivores lived on each square kilometre."
Record Arctic temperatures in recent years have accelerated melting of Russia's permafrost that covers two-thirds of the world's largest country, according to a July report by the independent Climate Crisis Advisory Group.
Loss of Arctic permafrost could release as much as 240 billion tonnes of methane and carbon dioxide into the atmosphere by 2100, the United Nations' Intergovernmental Panel on Climate Change warned in a 2019 study.
The Zimovs' theory is that animals tramping snow into the ground in winter will slow or stop permafrost melting, while protecting soil that allows grass to grow in summer.
The grass reflects sunlight, helping cool temperatures and support the herds, while emissions from grazing so many animals are more than offset by the positive impact on the ecosystem, according to Dr Nikita Zimov.
They are conducting an experiment with 150 animals, including 20 camels transported north in the summer, horses, deer and buffalo, that are grazing on the project's 140 hectares of land in Russia's Yakutia region, which Nikita jokingly calls Jurassic Park in the Arctic.
Mammoth may eventually join them, according to Colossal, a Boston-area company co-founded by geneticist and biotech entrepreneur George Church.
"We aim for our first calves within four to six years," Mr Ben Lamm, its co-founder and chief executive officer, said in e-mailed comments.
Colossal's scientists have visited Pleistocene Park and are working on artificial womb research in the US that would support "hundreds and potentially thousands of woolly mammoth at the same time", Mr Lamm said.
The company uses gene-editing technologies to insert mammoth DNA into the genome of Asian elephant cells.
The long-term goal is to produce a herd of mammoth large enough to aid in rewilding of the Arctic tundra starting with Siberia, Mr Lamm said.
Russia will need 20 million animals to restore the ecosystem over about 20 per cent of its territory, according to Dr Nikita Zimov.
This would help absorb about 20 per cent of global greenhouse gas emissions caused by humans, as much as four times the amount Russia now produces annually, he said.
Dr Sergey Zimov, 66, was among the first scientists to publish studies in the 1990s warning of the climate threat from melting permafrost.
He was co-founder and director of the Northeast Science Station near Chersky in Yakutia.
When the Soviet Union collapsed, he sold his own apartment to keep the station going, renaming it Pleistocene Park in 1996.
Their theory is unproven so far. While animals trampling snow may help slow degradation of the permafrost, the vegetation issue "is a bit more tricky", said associate professor Dmitry Streletskiy at the Columbian College of Arts and Sciences at George Washington University.
Still, "Sergey is indeed a world class scientist" and the idea "may work until proven otherwise", he said.
Animals disturbing the soil in summer could help warm the permafrost, even if they cooled it in winter by tramping down snow, said Professor Ted Schuur at the Centre of Ecosystem Science and Society at Northern Arizona University, who has published articles with Dr Sergey Zimov on the permafrost.
While restoring mammoth to the Arctic to avert global warming "would be cool", the project can work with currently available animals, said Nikita.
Alrosa PJSC, Russia's largest diamond miner that also works in Yakutia, recently agreed to sponsor an expedition to bring musk ox to the park, he said.
Unless Arctic thawing is stopped, emissions cuts set out in the 2015 Paris climate accord "will be insufficient, to put it mildly", Dr Zimov said.
They "will be discounted to zero."