Resurrection from permafrost and other ice-age legacies

A Siberian arctic ground squirrel knew precisely where to bury her rainy day stash of seeds: in permanently frozen soil called permafrost. She never returned to retrieve the treasures in her soccer-ball sized burrow.

Nearly 32,000 years later, two Russian scientists, Svetlana Yashina and David A. Gilchinsky, found her hoard and performed a near miracle: They regrew a plant that had shared the Siberian plains with mammoths, wooly rhinoceroses, and giant bison. The scientists reported their discovery in February in the Proceedings of the National Academy of Sciences. The plant, Silene stenophylla or narrow-leafed campion, serves as an example of the rich biological material encased in permafrost, an ice-age legacy totaling almost one fifth of the land area on our planet.

That same rich biological material also poses a mammoth threat, if you’ll excuse the pun. A 2009 study reported by the Global Carbon Project based in Australia estimates that all the frozen plants, carcasses, and megafaunal droppings from ice ages past amount to over 1.5 trillion tons of carbon compounds — about twice the amount of carbon currently drifting in the atmosphere as carbon dioxide, methane and other compounds. Our feverish world is melting permafrost quickly, converting megatons of potential treasure into heat-retaining greenhouse gases.

Good news first: The Russians’ work shows that living things are tough (and also that human beings are pretty clever). Thirty-two thousand years in the deep freeze didn’t prevent Silene from reproducing—although she did need a little help from her scientist discoverers. Silene’s seeds failed to germinate, but Yashina coaxed a few of Silene’s placental cells (like the whitish, seed-filled inner core of a bell pepper) into growing into complete and seed-bearing adult plants. Placental cells, like stem cells in animals, retain an embryo-like ability to express all the genetic information in their intertwined strands of DNA.

S. stenophylla still lives today in the arctic, but the ice-age variety resurrected by the Russians produces wider flower petals, slower growing roots, and more bud growth. A complete comparison of ancient and modern genomes will surely provide a roadmap to the evolution of a species adapting to a warmer, post-glacial climate.

The Russians’ discovery and research provides encouragement to seed banks around the world, including the National Center for Genetic Resources Preservation (NCGRP) in Fort Collins. Their work proves some seeds can successfully serve as cold-suspended templates for preserving rare and endangered plants. Dr. David Dierig, Research Leader and Location Coordinator at NCGRP, said, “The important thing to remember is that not all seeds react and store the same way. There is a lot of research going on in the seed world about why some seeds are recalcitrant when other seeds (orthodox) store for very long periods of time (maybe beyond 32,000 years).”

Now the bad news: Earth’s backlog of carbon trapped in permafrost over the last three million years represents a climate wild card that may tip Earth’s climate into a long-term hothouse cycle. Such warm conditions—with no permanent ice at the poles—are actually more typical than our relatively chilly present. Dinosaurs, for example, evolved and came to dominate Earth ecologies during a hothouse phase lasting 160 million years.

Long-term climate patterns depend on a range of factors, including the slow drift of continents, tectonic activity, and how land mass configurations and topography influence ocean currents and atmospheric weather systems. With continents in their modern positions, celestial mechanics dictate cold cycles. Earth wobbles as it spins, its axis tilts toward and away from the sun, and its distance from the sun changes in patterns that conspire to periodically nudge the planet into ice ages. Living things also contribute to climate change by altering the levels of so-called greenhouse gases, like carbon dioxide and methane, in the atmosphere. The first forests, covering vast tracks of land in the Late Paleozoic, trapped huge stores of atmospheric carbon in their tissues, providing most of our gas, oil and coal reserves today.

Our prolific and energy-intensive human culture has now become a global climate-changing force as we burn the remains of these long-buried forests in our cars, thus amplifying the heating powers of Earth’s atmospheric greenhouse in a geologic eye blink. The National Snow and Ice Data Center in Boulder reported in September of this year that Arctic sea ice now covers just 3.41 million square miles. This beats a record minimum set in 2007 by eight percent and represents the smallest area ever measured since satellite records began in 1979, and, according to Science News editor Eva Emerson, may herald the end of an ice-age regime that has lasted 13 million years.

The resurrection of Siberian wildflowers reveals the potential for amazing biological discoveries within the enormous, ice-age sepulcher of frozen soil within the Arctic Circle. The fumes of decay from those vaults as they warm in the coming decades should also serve as a warning of the slumbering carbon elephant that threatens to move from the soil to the air and contribute to a global fever largely triggered by our own success as a species. Let’s hope our instincts for survival are at least as good as those of an Arctic ground squirrel.