Hunting climate clues in Antarctica
Brown geologists are braving subfreezing temperatures for three months to visit “the oldest ice on Earth.” Their goal? A better understanding of our planet’s climate history – and current conditions on Mars.
A team of Brown University geologists is going to extremes to learn about past climate on Earth and the present climate on Mars.
Seven faculty, postdoctoral researchers, and graduate students are in Antarctica to collect rock samples and study a region that holds climate clues dating back millions of years. For three months, the geologists will toil in the rugged Antarctic Dry Valleys, a region of freeze-dried gullies, ridges, and slopes. To move camp, they’ll need to call for a helicopter. For nourishment, they’ll rely on frozen food, crackers, and granola bars. They will melt snow for drinking water and cooking.
And they’ll shiver a lot, burning calories as they try to stay warm against temperatures that during their summertime stay won’t stray above freezing. “I expect to be about 30 pounds lighter when I get back,” Michael Wyatt, assistant professor in geological sciences and one of two faculty on the trip, said without a hint of amusement.
Located in the central Trans Antarctic Mountains, the Antarctic Dry Valleys (also called the McMurdo Dry Valleys) lie between the East Antarctic Ice Sheet and the Ross Sea. (See map, below.) The valleys, each about 50 miles long and nine miles wide, are mostly ice free, a fortunate turn of geological events considering that 98 percent of Antarctica is permanently covered with snow or ice.
The expedition is funded through a $470,000 grant from the National Science Foundation. The money covered research in Antarctica during the 2008–2009 austral summer season as well as this trip. Team members will detail their experiences in periodic dispatches from their camps, which will include photos and other graphics.
Taken collectively, the valleys comprise a unique ecosystem that holds clues to very important questions, said James “Jim” Head III ’69 Ph.D., professor of geological sciences, who is making his fourth trip to the continent. For one, the valleys have entombed volcanic ash up to 8 million years old within cracks in the terrain that geologist call polygons. The ash, which has fallen periodically through those millions of years, has remained essentially unchanged ever since, making it an ideal source to date periods in Earth’s climate history.
“It’s probably the oldest ice on Earth,” said Head, who along with Boston University geologist David Marchant wrote a paper two years ago detailing the Dry Valley’s unique characteristics.
Brown postdoctoral researcher Gareth Morgan and Brandon Boldt, a graduate student studying with Head, are part of a Boston University team that will plunge drills up to 40 meters deep in debris-covered glaciers to extract ice cores they hope will yield information about past atmospheric gases such as carbon dioxide, temperature and the types of life that existed at various geologic intervals. The group also hopes to find evidence for ancient bacteria and other signs of past life.
“This is a challenging activity, but it may help us to better understand our own planet’s climate history,” Morgan wrote days before he left for Antarctica.
Another group including Head, Brown research analyst James Dickson, and Laura Kerber, one of Head’s graduate students, are studying the geological processes that formed the Dry Valleys. Moving inland from the coast, scientists have identified three distinct climatic zones in the valleys. Each of these “microclimates” has distinct signatures that can be interpreted by studying how rocks have been altered by wind, temperature, water, and chemical reactions.
The researchers will gather rock samples at dozens of locations, marking precisely the spot at which each sample is gathered. By analyzing the mineral composition of the rocks, the scientists can “see how they’ve changed, how they’ve been altered in these different climate zones,” Wyatt explained.
In addition to painting a picture of Earth’s past, the Antarctic rocks will present a vivid picture of Mars’s present. Scientists like to say that Antarctica is the closest that one can get to Mars’s environment. The climates are similar – hyper-arid, windy, and frigid. Just as important, Antarctica has landforms, such as polygons, gullies, and debris-covered glaciers that are strikingly similar to regions on Mars. So, the thinking goes, by studying rocks from the Dry Valleys, scientists can get insights into the geology of Mars – and help answer the elusive questions of how much water exists on Mars and what it has been doing there.
“If we’re able to map the minerals here and compare it to minerals we also see on Mars (through data gathered from orbiters and landers) … we are setting a minimum limit for how much water you need to produce the same alterations that we see in the Dry Valleys,” said Wyatt, who will team with graduate student Mark Salvatore on that aspect of the research.
“It’s totally exciting,” added Head. “You can sit in your office and look all day at images of Mars. And you try essentially to place yourself on the surface of Mars. But there is no substitute for going to this Mars-like place on Earth and having an immersive experience.”
The Brown research team will file periodic dispatches and photographs from the Antarctic to be published on Today at Brown.