To develop the approach, researcher Barry Lomax and his colleagues at the University of Sheffield and other leading UK institutions analyzed spores held in the British Antarctic Survey's collection from South Georgia Island, a UK territory in the far southwestern corner of the Atlantic Ocean. They discovered that since the 1960s, spores from living land plants have shown a three-fold increase in the concentration of UV-B absorbing pigments to protect themselves against a 14 percent decrease in stratospheric ozone, says Lomax.

"We have initially been investigating whether plants of palaeobotanical significance are capable of adapting to changes in UV-B radiation," said Lomax. In particular, they studied the UV-B response of the club moss Lycopodium magellanicum, a native of South Georgia Island.

"Now that this has been established we are investigating possible changes in terrestrial UV-B flux during the Permian-Triassic boundary (251 million years ago)," said Lomax. That boundary marks the largest mass extinction in the Earth's history and also coincides with the largest known eruption of lava and potentially ozone-destroying gases - the Siberian Traps.

The latest results from the ongoing work will be presented by Lomax on Wednesday, 10 August, at Earth System Processes 2, a meeting co-convened by the Geological Society and Geological Association of Canada this week in Calgary, Alberta, Canada.

The modern increase in UV-B at South Georgia is the direct result of high latitude springtime ozone destruction in the stratosphere caused by decades of releases of human-made chlorofluorocarbons (CFCs). The situation may have been the same a quarter billion years ago, except that the earlier ozone-dest
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Contact: Ann Cairns
acairns@geosociety.org
303-357-1056
Geological Society of America
9-Aug-2005