Earth’s Oldest and Coldest - Age Week


By Jess Goulart

All photos courtesy of Adam Lewis.

Buried under thick sheets of ice and mountains of snow lies the land of Earth’s southernmost continent. With an average temperature of negative 30 degrees, plus the pummeling of winds so strong they sculpt rocks, the possibility for most life ceases to exist. Only the warmest, driest recesses support a few terrestrial species.

But Antarctica didn’t always look so barren.

In 2000, researcher Adam Lewis and Boston University graduate student Jane Willenbring set out on an Antarctic expedition to explore the glacial geology of the Dry Valleys. The valleys are located at the southernmost point of the Transantarctic Mountains, which divide the continent into an eastern and western half. They are unique in their absence of snow, and considered one of the world’s most extreme deserts. It’s been said walking on the valley floor is akin to walking on black pavement.

Out on the field, Lewis pulled some tiny fibers from a particular surface. Later, it was discovered that the surface was formerly a deep lakebed, and the fibers were ancient moss. Further investigation led to the finding of wooded plant fossils and hundreds of types of insects, now extinct.

Antarctica, Lewis concluded, was not always a mass of frozen earth, and in fact, its terrain once sustained an alpine-like ecosystem with flowing, deep lakes, similar to that of the high regions in New Zealand.

Lewis explains to BTR that corroborating evidence from around the world confirms that whatever caused the Antarctic deep freeze was experienced globally, at around 14 million years ago. In geological time, whatever the event was, occurred extremely quickly–but that’s not what interests Lewis most.

Most fossils, Lewis says, are rocks in which the original organic material was buried and eventually replaced by minerals. By looking at a fossil, the observer sees the impression of a living material that is no more.

Close-up of moss specimen.

Such is not the case with the Antarctic moss specimens.

“These are freeze-dried plants that have not been replaced by minerals, they are still the plant tissue and they are millions of years old,” he explains. “That is extremely rare.”

Because of the freeze-drying, the plants and bugs appear like they died only a few months ago, though in fact they are dated to around 20 million years. That’s 4,000 years longer than the mummies of Egypt. When submerged in water, the moss even puffed back up as if alive again. Just recently, researchers were able to actually resurrect 1,500-year-old moss from a neighboring part of Antarctica–the first time in history that an organism of that age was ever brought back to life.

The key finding, emphasizes Lewis, is that Antarctica’s climate must have remained exactly as it is now for 14 million years. Any possible warming would have caused bacteria to invade the tissues and destroy the organisms. It’s the only place in the world where this climactic phenomenon is observed.

Adam Lewis (left) and Allan Ashworth (right) at work.

A year or two after Lewis’ initial lakebed discovery, he recruited help from North Dakota State University distinguished professor and researcher Allan Ashworth, to continue unfolding the history. Ashworth tells BTR that, in terms of understanding global warming, the history of the Dry Valleys is pertinent because it indicates there is some sort of temperature threshold that, when crossed, triggers climate rearrangement.

“When we think about global warming, there are these nice models that show us in 2100 it will look like ‘X,’” says Ashworth. “It’s shown as a straight line and [has a] gradual series of changes that occur. But the fact is there’s another mode of operation on the climate system, and that is one where you can have these much more rapid changes and reorganizations of the climate, and we don’t really understand what causes those.”

Of course, that rearranging happened a long time ago. To study more recent developments in climate change, some of Lewis’ current research focuses on small fluctuations in temperature over the last thousand years. From analyzing his collected data from the Dry Valleys, he learned about brief warming periods (one from 1,000 to 3,000 years ago, and again from 8,000 to 10,000 years ago) that caused small streams to trickle down the mountains and pile up deposits of sediment.

Determining exactly how much warmer these periods were, and why they got that way, will be useful to establish for further studies about climate change.

“If water starts to come down these [mountains] again, we know that hasn’t happened in a few thousand years, and that’s a sign that we might be approaching some sort of threshold,” Lewis reasons.

Camping in Antarctica.

As many interesting and useful conclusions the researchers may draw from their Antarctic excursions, working in this environment obviously isn’t easy. In 2008, Emmy-award winning filmmaker Anne Aghion released the documentary Ice People, after she and her crew spent four months living “on-the-ice” with Ashworth, Lewis, and their team. The footage permits a glimpse into the challenging life on the world’s coldest continent, as researchers search for more to prove the space was once verdant.

“We have to supply for ourselves and cook for ourselves and just live out there, and it’s quite hard on the body, with the low temperatures and the wind,” Ashworth describes.

For all of the trying challenges, Ashworth does experience bouts of awe, reveling in the special feeling of “standing somewhere where absolutely no one else has ever stood.”

From the harsh, but redeeming existence for humans in our current era, to the lush life of mosses from millions of years ago, Antarctica stands as a fascinating platform to delve into the contemporary and ancient mysteries of our dynamic planet.