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Scientists read Antarctic mud for climate change insight

A four-inch core sample is a chapter of ancient history in which a Neanderthal amoeba or a worm can thicken the plot for researchers.

By Contributor to The Christian Science Monitor / February 20, 2008

Land Grab: Scientists at the Antarctic Drilling Project's stratigraphy lab use toothpick to stake claims on petrified mud that they want to study.

Douglas Fox

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With summers both intense and ephemeral, life here is a race against the revolving seasons. Summer daylight never ceases at this US research base on Ross Island, just off the coast of Antarctica. The sun runs endless laps around the sky, and for those who live here, work never stops.

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This blending of day and night centers on the 24-hour stratigraphy lab. Inside the nondescript metal building perched on stilts, geologists from around the world indulge, of all things, their collective love of petrified mud. Two shifts of scientists work around the clock examining a 4-inch-wide column of stone – a new section of which is delivered daily from a drill that, by the end of the season, will have penetrated three-quarters of a mile into the ocean bed.

This stone began as mud that settled on the ocean floor and curdled over eons into rock. From it, the scientists are reading geologic tea leaves between 14 million and 19 million years old: fossils and chemical signatures that provide a record of past climates – and show how Antarctica's ice sheets responded to climate swings.

In doing so, they hope to predict how well Antarctica's ice will withstand rising temperatures in the century to come.

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The two crews of scientists converge at 8:30 each morning: One has worked all night beneath the hum of fluorescent lights, and the other has just risen to pick up where the vampires left off.

Their one-hour meeting consists of a slide show of discoveries made overnight – worms petrified in million-year death throes, fossilized sea-shells, microscopic diatoms, and bits of gravel – all suspended in the core.

The slide show is lively, punctuated by questions and murmurs of surprise. "Here is something very weird," announces one presenter, "a bryozoan having some sort of affair with a foram." He points out two tiny fossils caught for eternity in a compromising interspecies pose. A nerdy joke – but the audience likes it.

After seeing slides, the crowd pours down the hallway for another daily ritual – the "land grab." They browse over tables where sections of last night's core lay end to end. Anywhere the gawkers find something they want to study in detail, they jam a toothpick with a paper flag into the cardboard case that cradles the core. The flags carry labels to identify the owners. "Pmag-ers do it better," say some of the flags – a cryptic boast to the consummate hipness of paleomagnetists who study the magnetic signatures of ancient rocks. Other flags sport the face of a lion; worms and snails were the lions of the mud, explains their owner, who searches the core for fossils of the predatory vermin.

Technicians will saw apart the core and deliver pieces to those who staked a claim.

The process repeats daily for eight weeks during the Antarctic summer. Each day offers surprises – and monotony. Science, like the seafloor, is sedimentary. Those fossils and diatoms aren't breakthroughs in themselves, but patient study of them gradually reveals a picture of the past.

A similar core drilled last year has already revealed surprises: the Ross Ice Shelf, a Spain-sized slab of ice that hangs off Antarctica's coast, has responded strongly to past climate shifts.

"We saw something like 50 cycles [in a few million years] of the Ross Ice Shelf disappearing and coming back," says Fabio Florindo, a soft-spoken geologist from the National Institute of Geophysics and Volcanology in Rome. He oversees work here, part of the Antarctic Drilling Project (ANDRILL), along with David Harwood, a micropaleontologist from the University of Nebraska in Lincoln.