The oceans may play more of a role than previously suspected in climate development and global warming, a University researcher said after studying a mathematical model that was designed to simulate the climate of the Eocene time period.

Scientists study other geological time periods to help predict the environment's behavior.

Eric Barron, associate professor of geosciences, studied the Eocene because it was an extremely warm period that many people think was characterized by higher atmospheric carbon dioxide levels, he said.

"Perhaps it offers clues to future greenhouse warming," Barron said.

Many scientists believe the greenhouse effect is responsible for regulating global temperature over long-term geological periods.

Climate modeling of the Eocene period, which took place 40 million years ago, has been difficult, he said. When information of the period is plugged into a mathematical model, it does not mimic known climatic conditions.

"The study shows that there is a distinct problem (with) trying to explain everything and that is an interesting result in itself. It suggests that climates work in a very different way than what we were hypothesizing from what we know about the present day," Barron said.

"The problem is that some things look really good and a lot of things just don't match. I think the very best bet for the reason it doesn't match is because we're not doing a good job of including the oceans in our models," he said.

Barron's more recent model ran on a supercomputer using the University's network link with the National Center for Atmospheric Research in Boulder, Colo., he said.

During the Eocene, crocodiles inhabited such places as Wyoming and Ellesmere Island north of Greenland. The Rocky Mountains supported subtropical vegetation and there was little polar ice, he said.

"This is an interesting period, because this is finally the time period when you went from a really warm climate (Eocene) to the cold climate that we have today," said Lisa Sloan, who is working on the recent study as part of her doctoral dissertation.

The oceans' previously unsuspected role lies in their ability to transport heat, Sloan (graduate-geosciences) explained.

"You get excess heat at the equator and you lose it the poles," she said. "To balance that out -- so that the globe over long periods of time is not burning at the equator and turning into an ice cube at the poles -- there's always a redistribution of heat going on."

Barron said much of today's heat transport by oceans is related to the currents. Very cold salt water (which is heavier than warmer salt water) sinks deeply at the poles. Traveling to the equator, it is heated, rises to the surface, and returns to the poles to continue the cycle.

The simulations used for the study were all based on the idea that deep water formed in the same areas and that the atmosphere was responsible for the climate, Barron said.

"I think it is distinctly possible if we were to match up all the data in the Eocene, the best way would be that (the Eocene's) deep water didn't form at the poles but it formed at the low latitudes," he said.

Barron said he has already done some Eocene climate models that take the revised ocean idea into account.

"We've already . . . obtained the first clues that (these models) may work," he said. "This would be a world in which the oceans did all the work and the atmosphere did very little work at all," he said.

But another idea, supported by James Kasting, associate professor of geosciences, is that carbon dioxide could have played a large part in the Eocene climate.

Global temperature during the period can best be explained by increased carbon dioxide in the atmosphere, he said. Latitudinal temperatures in which the equator was cooler while the poles were warmer cannot yet be explained.

Concerning the oceans' role in the period, Kasting said, "I would expect that poleward heat transport would be lowered."

In looking at the period, he gave two reasons why the oceans may not have affected the Eocene climate.

Even if deep water formed in the tropics during the Eocene, Kasting explained, that does not necessarily mean that it transported heat to the poles. Secondly, wind stress on the oceans was lower in that period; therefore, there was less ocean movement.

Sloan agreed, noting that since the topography of the ocean during the Eocene is unknown, the direction of heat transport is uncertain. However, Sloan and Barron both believe it was toward the poles.