BY JAMES J. LIDINGTON

If you think it's been cold recently, wait a few thousand years. In his new book, "Ice Drift, Ocean Circulation and Climate Change" (Praxis Publishing, 2000), Jens Bischof says the global climate may well be on its way to another ice age, contrary to the much-publicized global warming scenario.

Bischof, a research assistant professor in the Department of Ocean, Earth, and Atmospheric Sciences, writes that marine sediments in northern ocean waters make the present time look more like a brief intermezzo between two ice ages rather than a long-lasting period of warm weather. The next ice age, he says, may be lurking ahead.

According to the publisher, Bischof's work "is the first book to focus on the interactions between ice, the ocean and the atmosphere and to describe how these three components of the climate system influence each other."

As such, says Bischof, it represents a contribution to the ongoing climate debate. Global warming, a trend to slightly higher temperatures identified in the 1970s, is commonly ascribed to the release of greenhouse gases from burning of fossil fuels. But the effects of naturally occurring climate changes have been ignored for the most part, Bischof contends.

In his book, Bischof describes some of these natural climate changes and includes the results of 14 years of research that have never been published in scientific journals.

As a geologist, Bischof's main interest is the reconstruction of ocean and atmospheric circulation patterns. He notes that ice, wherever it forms in contact with land, encloses rock and mineral debris from its point of origin, which is eventually dropped as the ice drifts along in the ocean and melts.

The drifting, or rafting, ice leaves a trail of debris as deep-sea sediments. Debris found in up to 1.5 million-year-old sediments from the Arctic Ocean, originally scraped from land masses by glaciers as they moved toward the sea, reveals complex circulation patterns of ocean surface currents, some of which are remarkably different from those of today, Bischof says.

By 1998, when his publisher asked him to write the book, his research had produced a stack of unpublished material too voluminous for a conventional research paper. The wealth of data Bischof has collected over the years is also evident in the Oceanography and Physics Building lab he shares with his colleagues. There, boxes with geologic samples are stacked to capacity.

One corner is filled with plastic bags that contain chunks of ice he collected in the Arctic last summer. All that remains are water, silt, rock and mineral residue. Another box holding vials of larger fragments sits nearby. All together, some 370 varieties of mineral and rock fragments are represented here.

The contents of each bag and vial tell their own story, Bischof says. Coal fragments in sediment from the Norwegian Sea, for instance, testify that ice drifted from eastern Siberia into the Norwegian Sea, a journey of more than 4,000 kilometers, during a three to four-year span of the Holocene period (the last 10,000 years of earth's history), a relatively warm time since the end of the last ice age.

In years past, the thinning of the Arctic ice cap has been looked at as an indicator of global warming, but the change in thickness could simply be the result of different atmospheric circulation patterns and not changing temperatures, according to Bischof.

"From time to time, the circulation in the Arctic Ocean changes from a mode in which ice remains trapped there for long periods of time, thereby giving ice the chance to grow in thickness, to a mode promoting the export of ice and icebergs out of the Arctic," he explains.

This leads to lower salinity in the sub-Arctic waters and cools the climate. When that happened in 1955, Bischof said, Europe was immediately plunged into a deep freeze so cold that motorists had to dig their cars out from snowdrifts in Naples, Italy. This drastic change in the weather resulted in 2,000 human casualties around the Mediterranean.

In the foreword to his book, Bischof writes, "... this book was written in the hope that it may convince a larger number of scientists about the usefulness of 'following iceberg's footprints,' as Eystein Jansen once called it, as not just a complementary, but an essential and very powerful tool for paleoceanography."

Bischof, a native of Oldenburg, Germany, received his master's and doctoral degrees in geology in 1983 and 1990, respectively, from Kiel University in Germany. His doctorate is a treatise on the dispersal patterns of ice-rafted debris in the Norwegian Greenland Sea.

Bischof joined Old Dominion in 1992 as a postdoctoral fellow and was promoted to the rank research assistant professor in 1995. His research has been funded by the National Science Foundation and the Office of Naval Research.