Jurassic records yield clues to global warming.........

Washington: Findings from fieldwork along the North Yorkshire coast reveal strong parallels between the Early Jurassic era of 180 million years ago and current climate predictions over the next century, according to researchers at Plymouth University, UK. 

Through geology and palaeontology, they've shown how higher temperatures and lower oxygen levels caused drastic changes to marine communities, and that while the Jurassic seas eventually recovered from the effects of global warming, the marine ecosystems that returned were noticeably different from before. 

"Our study of fossil marine ecosystems shows that if global warming is severe enough and lasts long enough it may cause the extinction of marine life, which irreversibly changes the composition of marine ecosystems," said Professor Richard Twitchett, from the University's School of Geography, Earth and Environmental Sciences, and a member of its Marine Institute. 

Professor Twitchett, with Plymouth colleagues Dr Silvia Danise and Dr Marie-Emilie Clemence, undertook fieldwork between Whitby and Staithes, studying the different sedimentary rocks and the marine fossils they contained. This provided information about the environmental conditions on the sea floor at the time the rocks were laid down. 

The researchers, working with Dr Crispin Little from the University of Leeds, were then able to correlate the ecological data with published data on changes in temperature, sea level and oxygen concentrations. 

The team found a 'dead zone' recorded in the rock, which showed virtually no signs of life and contained no fossils. This was followed by evidence of a return to life, but with new species recorded. 

"The results show in unprecedented detail how the fossil Jurassic communities changed dramatically in response to a rise in sea level and temperature and a decline in oxygen levels," stated Professor Twitchett. 

"Patterns of change suffered by these Jurassic ecosystems closely mirror the changes that happen when modern marine communities are exposed to declining levels of oxygen. Similar ecological stages can be recognised in the fossil and modern communities despite differences in the species present and the scale of the studies," he added. 

The results are revealed for the first time in this month's PLOS ONE scientific journal.