At the National Antarctic Research Facility, scientists are discovering some of the coldest facts about Earth's curious habits of changing its temperature over time.
 

    The Earth is warming! The Earth is warming!
In the last days of the 20th Century, the cry of global warming is being heard across the planet, warning of dire consequences from altered weather patterns, melting ice caps, and rising sea levels.
    But are the Earth's atmosphere and oceans really warming or is this just another Chicken Little theory of impending doom? If it is happening, are we humans to blame for it?
    The United States Environmental Protection Agency (EPA) believes that global warming is indeed happening, citing several observations consistent with theories of global warming. Over the past century:

        o Global temperatures have risen nearly a full degree Fahrenheit. This increased temperature has caused more water to evaporate into the atmosphere, resulting in more rainfall.
        o Such rain has increased over the world's continents by one percent and has helped melt glaciers and sea ice, increase run-off and thermally expand sea water.
        oSea levels around the world have risen six to eight inches.

    Punctuating these findings was the announcement early this spring from the National Snow and Ice Data Center that satellite images showed two huge chunks of the Larsen Ice Shelf breaking off from the Antarctic Peninsula. Since they first started keeping records in the 1940s, scientists have known that this region has warmed by 4.5 degrees Fahrenheit, and have documented evidence that Antarctica is melting.
    As for human involvement, the Intergovernmental Panel on Climate Change (IPCC), an international organization established by the United Nations in 1988, concluded in its 1995 report on climate change that human activity is indeed having an impact on world climate. This conclusion, still hotly contested by many scientists, was nonetheless based on a review by 2,500 experts from 60 nations of 20,000 peer-reviewed articles on climate change.
    The report confirmed earlier findings that human-generated greenhouse gases-carbon dioxide, methane, nitrous oxide, and sulfur dioxide-that suggest humans are altering the chemical composition of their atmosphere. The report further concluded that without taking steps to reduce these emissions, global temperatures could rise from 1.4 to 6.3 degrees Fahrenheit over the next 100 years.
    This would be the fastest rate of warming since the end of the last ice age more than 10,000 years ago, when global temperatures jumped 13 degrees over a 50- year period.
    The topic of ice ages raises an intriguing question about global climate change:how and when did the earth ever get so cold in the first place? When and why did these cold periods come and go through the eons? These are question FSU researchers may be uniquely prepared to help answer.

Sedimental Journey

Florida seems an unlikely place to house a facility devoted to Antarctic research. Nevertheless, since 1960, FSU has been home for the Antarctic Marine Geology Research Facility.
    Established by the National Science Foundation (NSF) as a national curatorial and research center, it has become a library for one of the world's largest collections of marine sediment cores and is the sole repository in the United States for marine sediments from the Antarctic region.
    Dr. Sherwood Wise (Ph.D., Illinois) is principal investigator with-and a 26-year veteran of-the Antarctic Research Facility. A marine geologist, he specializes in micropaleontology-the study of fossilized microorganisms-and sedimentology, how sediments are formed and deposited over time.
    During most of earth's history, its rocky crust has been constantly eroded by wind and water. Layers of eroded sediments composed of fine particles, stones, and rocks have been deposited year after year on both land and sea floor. Once life developed, it also left its mark in the layers of sediment. As these layers built up over thousands and millions of years, they became a record of events for the region in which they formed.
    For over 40 years, geologists have pierced through those layers, taking long tubular samples called cores. The deeper the cores go, the older the sediments, although sometimes,to the delight of geologists,geological action folds the layers, placing older sediments above the younger making them more accessible.
    By identifying the species of organisms that are present and analyzing the materials in the core sediments, these scientists can identify the climatic and geological conditions that existed at the time the sediments were laid down.
    Towards that end, Wise and his research team have been studying Antarctic marine cores, dating materials and determining which microorganisms lived in the various layers, and when they lived, to learn how that continent's climate has changed over the past 80 million years.
    Hundreds of millions of years old, Antarctica is as ancient as it is remote. Once the home of semi-tropical forests and dinosaurs, it is now the coldest, highest, driest, and windiest, of the earth's continents. Fully 98 percent of its land mass is covered with ice sheets, three miles deep in some places, a mass that holds as much as 70 percent of the earth's fresh water.
    When and how this continent was transformed from a semi-tropical paradise to a frozen desert is a question geologists have been trying to answer since the continent was opened to scientific inquiry in 1957. Surprisingly enough, that question is finding its answer in plate tectonics-the theory that explains the movement of continents over time, as well as phenomena like earthquakes and volcanoes.

The Big Chill

    The issue of the earth's recent ice ages has been a puzzle because geologists have established that for 90 percent of its history, the earth has been free of ice ages. The age of the dinosaurs was one such time. For hundreds of millions of years, glaciers only existed on mountain tops and polar ice caps were nonexistent or transient. In fact, it was so warm 55 million years ago, at the peak of a warming trend, that subtropical forests, like those found growing in the southeastern United States, could be found growing in the arctic.
    Then something changed. About 50 million years ago, the earth began to cool. By 1.8 million years ago, it was in the depths of an ice age with ice caps at both poles and massive ice sheets spreading across the continents of the northern hemisphere. The ice sheets advanced and retreated several times, retreating for the last time-or so we'd like to think or hope-a mere 10,000 years ago.
    None of these climatic events was happening in an unchanging world, however. Through the slow process of continental drift, the continents were on the move, being carried on crustal plates floating on a sea of magma.
Three hundred million years ago, all the world's continents were joined together forming one vast supercontinent, which geologists call Pangea, extending from pole to pole. Scientists speculate the earth enjoyed a moderate climate during this time was because warm tropical waters were free to circulate across the globe.
    Over the next 250 million years, Pangea split into the six continents we know today, with the Pacific Ocean slowly shrinking and the Atlantic Ocean expanding, pushing the Americas closer to Asia.
    In the late 1980s, Wise and his research team found evidence in Antarctic marine sediments suggesting that widespread glaciation of Antarctica had begun much earlier than generally believed. Previous studies had placed the first occurrence of glaciers on Antarctica at 15 million years ago.
    But at three different locations around the continent, Wise and his team had found ice-rafted debris,mainly grains of sand,that had been carried out to sea by glaciers, in sediments that were at least 35 million years old. Pushing back the date for the first known period of Antarctic glaciation allowed Wise to speculate about the cause.
    The freezing development of an ice sheet didn't appear to be caused exclusively by the polar position of the continent. Antarctica had moved to its near polar position nearly 100 million years ago. Yet according to the sediments Wise had examined, it wasn't until at least 35 million years ago that the glaciers developed. It was, he and other scientists now believe, the separation and isolation of Antarctica that created its current ice age.
    "Once the connection between Antarctica and the other continents was broken, the Antarctic circumpolar current was established," Wise explains. "And once that happened, Antarctica was isolated from the warmth of the world's oceans and it went into deep freeze. As that process neared completion, we see the first continental glaciation."
    As went Antarctica, so went the world. In its frozen isolation, the Antarctic continent has become perhaps the strongest influence on our current global climate.
    Scientists are just beginning to understand how the presence and extent of the Antarctic ice sheet controls global atmospheric and oceanic circulation patterns. Now the question is, what does that mean for the future of earth's climate and for the prospective impact of human induced global warming?
Sudden and dramatic warming trends have occurred in recent times-without human intervention. Last fall, while working with a new drilling project (the Cape Roberts Project) that produced some (relatively young) million-year-old cores, FSU scientists and their colleagues found the usual layers of sand brought out to sea by glaciers.
    Then they got a dramatic surprise, said Wise.
    "We found two meters (six feet) of a shell bed, like you expect to see some place like Sarasota-full of mollusks, snails, clams... there's every kind of organism in there that you'd see along the coast of Florida."
The find has only one plausible explanation: Apparently, the waters surrounding Antarctica about a million years ago grew warm, very fast. But just as suddenly as it had warmed, it turned cold again and the glacial sands again dominated the sediment record.
    Florida State's Antarctic explorers are continuing to investigate their cache of sediment cores for more clues about the history and impact of the Antarctic climate on the world. The Cape Roberts Project will continue through 1999, and half of its split cores will be housed at FSU.
    Rather than drilling into sediments from ships, the multinational team is setting up a drill rig on the Ross Ice Shelf at Cape Roberts, using the ice as a platform, not unlike an offshore drilling rig. They hope to drill deep enough and in enough places to collect almost a mile of continuous sediment history, taking advantage of areas where older sediments have been pushed closer to the surface. They hope to find sediments 80-100 million years old, or even older, and discover more clues about Antarctica's past and the future of planet earth.

PHOTO 1: ICY FOOTHOLD:
A research base camp goes up on the wind-swept Ross Ice Shelf about five miles off McMurdo Station