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For climatologists, part of the challenge in predicting the future is figuring out exactly what happened during previous periods of global climate change.

One long-standing climate puzzle relates to a sequence of events 33.5 million years ago in the Late Eocene and Early Oligocene. Profound changes were underway. Globally, carbon dioxide levels were falling and the hothouse warmth of the dinosaur age and Eocene Period was waning. In Antarctica, ice sheets had formed and covered much of the southern polar continent.

But what exactly was happening on land, in northern latitudes? When and how did Northern glaciation begin, and what does this knowledge add to the understanding of the relationship between carbon dioxide levels and today's climate?

An international team that included Dr. David Greenwood, an NSERC-funded researcher at Brandon University, now provides some of the very first detailed answers, and they come from an unusual source.

"Fossils of land plants are excellent indicators of past climates," said Dr. Greenwood. "But the fossil plant localities from the Canadian Arctic and Greenland don't appear to record this major climate change, and pose problems for precisely dating their age, so we needed to look elsewhere."

The "where" was in marine sediments entombed when the North Atlantic Ocean was beginning to open, and lying now at the bottom of today's Norwegian-Greenland Sea. Sediment cores taken from there contained a record of ancient spores and pollen blown from the continent to the west.

"These marine sediment cores give us a very precise chronology of the changes in the dominant land plants," said Dr. Greenwood "and since many of these species have modern relatives, we can assume that the temperatures and environments they lived in were very similar."<
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