SCIENCE LAB SEARCH

A WORLD ABLAZE

Fire came before the ice that now covers Antarctica.

Imagine the forests of Chilean Patagonia : wet and cold, dense with monkey puzzle trees and other hardy conifers. Now imagine it with dinosaurs walking around. And on fire.

This is what Antarctica was like 75 million years ago during the Creaceous period, an era known by researchers as a ''super fire world.''

A new paper by scientists in Brazil proves that these conflagrations did not spare any continent, even one that is today known for its dry, inhospitable climate and a landscape largely free of vegetation.

Although research on such ''paleofires'' has been going on for decades, Antarctica was ''first considered a region without high fires,'' said Andre Jasper of Brazil, one of the authors of the paper.

Scientists can find evidence of paleofires by studying charred tree rings, by analyzing sediment in ancient lakes and by examining molecules in fossilized charcoal. For this paper, the researchers analyzed charcoal extracted from sediment on James Ross Island.

The big remaining question about these ancient fires is the cause.

The Cretaceous period was a time of mass extinctions, fluctuating amounts of oxygen in the atmosphere and changes in the amount of vegetation covering the planet.

Did fires cause these changes, or did the changes cause the fires?

[ Emily Cataneo ]