ICE CHEST:CAN GREENLAND'S TREASURE TROVE OF FROZEN RAIN REVEAL THE STORY OF
EARTH'S CLIMATE?

It sounds like part H. G. Wells's The Time Machine, part Jules Verne's
Journey to the Center of the Earth, and part Steven Spielberg's Back
to the Future. But the key to the future may be buried in the past-in
layers of ice that comprise a frozen record of the earth's atmosphere.

That's what scientists with the Greenland Ice Sheet Project (GISP) have
discovered since they began analyzing Greenland's ice samples. The first
GISP, carried out in the Seventies and Eighties, produced samples 100,000
years old. During GISP II, a five-year, $20 million project scheduled to
break ground this spring, researchers will dig 3,000 meters into the ice
and turn back the climate clock-as far back as 200,000 years. Their
goal: understanding the forces behind climatic change.

Layered like tree rings, the ice allows researchers to date the atmosphere.
While tree rings show changes in precipitation and temperature, ice core
samples go further, reflecting the earth's global climate machine, says
Paul Mayewski, chief scientist for the project, which is funded by the
National Science Foundation.

Although technologies like satellite photography now map ocean currents
and other atmospheric variables, GISP II will help scientists interpret
changes by providing a database of climate history. "We know, for
instance, that the last ice age lasted 100,000 years and ended about
12,000 years ago; another long ice age ended about 130,000 years ago,"
says Pieter Grootes, a University of Washington geologist involved with
the project. "But the record for those periods is poorly detailed. If
we learn about them, we may be able to extrapolate those cycles in the
future."

Receiving less than three inches of rain a year, icy regions like Greenland
and Antarctica are deserts. Unlike arid deserts, however, the
precipitation is frozen and preserved, representing, Mayewski says, "a
phenomenal story about to be told," with a record of the atmosphere's
chemical composition, human activity, and other factors in Earth's history.

In preliminary findings, the Greenland ice team reported intriguing
atmospheric anomalies. During l8l5, for example, temperatures plummeted and
the period became known as the "year without a summer."

Contemporary paintings show skies with a yellowish tinge that scientists
now believe represents a rise in sulfur dioxide and volcanic particles
produced by the eruption of Tambora in Sumbawa, Indonesia. "With a
preserved 'piece' of precipitation from that year we can actually see
the composition of the atmosphere," Mayewski says.

The progression of industrial pollution also lies buried in the frozen
fields of the earth's history. "We can even detect when the United
States put the Clean Air Act into effect," Mayewski says. The breakdown
of sulfur dioxide (SO2) in the atmosphere produces sulfuric acid that
returns to the earth as acid rain. Specimens from the Greenland Ice
Shelf indicate sulfur dioxide emissions have decreased.

GISP II scientists, however, will learn about the earth's climate well
before the Industrial Revolution. Housed in geodesic domes that resist
the accumulation of snowdrifts, drills will bore 1,500 meters down to ice
layers representing the earth's last 10,000 years, The next 1,500
meters of ice, where the layers are more compact, will reveal a record
of the planet's preceding 190,000 years. The core samples will be cut
into sections, stored at low temperatures, and shipped for analysis in labs
around the world.

In a similar European venture, the Greenland Ice Project (GRIP),
researchers working just 30 kilometers away will collaborate with the
Americans to confirm results. Together the projects should produce a
definitive climate record of the Northern Hemisphere. But Mayewski is
already looking to the next stop in the frigid journey through time:
Antarctica. "That's where we have the oldest ice," he says. "We can go
back half a million years, maybe even two."