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Antarctica had a warmer past.

Remains of a 260,000,000-year-old forest of deciduous trees have been found in a region of Antarctica 400 miles from the South Pole. The discovery of fossilized stumps of Glossopteris, a seed fern now extinct, supports the view that during the Permian period - years 250-280,000,000 ago - Antarctica had a climate much warmer than it does today, according to Edith Taylor, a research scientist with Ohio State University's Byrd Polar Research Center.

Deciduous trees - trees that lose their leaves yearly - grow in temperate climes. The remains Taylor studied, found on a ridge of Mt. Achernar in the central Transantarctic Mountains, are at about 82 degrees south latitude. No forest ever has been found that far from the equator before. During the Permian period, the site probably was located at 80-85 degrees south latitude.

The discovery of such trees, instead of the short, shrubby conifers one might have expected to find, is further biological evidence to refute the claim some climatologists have offered that the South Pole was frigid during the Permian period. "Some climate models for this region have suggested that winter temperatures averaged -30 to 40 [degrees] Celsius and summer temperatures hovered around zero." In contrast, Taylor maintains that the climate of the Permian was quite favorable to the growth of deciduous trees.

A research team brought back several stump samples to Taylor's lab at Ohio State. After etching the petrified wood with acid, she used acetone and plastic to lift off thin layers of the wood to mount on slides. After that, using a microscope, she measured the width of each tree ring and found them to be extraordinarily wide. While the average width was about one-fifth of an inch, the largest measured almost one-half inch thick.

"These are the thickest rings ever found in a polar climate. Part of the reason that the plant grew such big rings was that, being near the South Pole, it had 24 hours of light throughout the summer." Also, Taylor found no frost rings, the telltale signs of freezing conditions. "This indicates that there were no hard frosts during the growing season when these trees still had their foliage."

Frost rings, which appear as a row of disrupted cells, are essentially scars formed in the early spring and late fall when low temperatures destroy living cells. "The fact that we see no frost rings and that the growth rings are so wide suggests that conditions were not marginal. Temperatures were consistently warm enough for steady growth throughout the summer."
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Publication:USA Today (Magazine)
Date:Jun 1, 1993
Words:420
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