IU geologists study ancient climate change

An international team of scientists that includes two IU geologists presented new evidence on ancient oceanic temperature changes that will be published in a upcoming issue of Geology magazine. \nSimon C. Brassell, the study's leader and an IU professor of geological sciences, said few data from the time period -- 120 million years ago in the Aptian stage -- existed before the five researchers obtained samples from "one of the best" Pacific Ocean sites. \nThe study, a joint effort with the Royal Netherlands Institute for Sea Research, found sea surface temperature variations of up to six degrees Celsius within the sequence, leading Brassell to suggest that oceanic temperature "still changes with a warm Earth." \nMembers of the team believe the scientific community can now better understand climate fluctuations because the Aptian time frame represents "a critical piece of the jigsaw" in the challenge of determining ancient climate activity, Brassell said. \nThe Aptian period is an important environmental benchmark because of notable movement in undersea plateaus that possibly caused increases in carbon dioxide and global warming, according to a copy of the report Brassell provided.\nAptian and present times share high carbon dioxide concentrations, making the study relevant to the current global warming conversation. Brassell said the purpose of the study is not to establish direct links but to make a series of inferences that help predict future patterns by considering the relative importance of various factors.\nThe link between naturally occurring Aptian carbon concentrations and current emission levels shows evidence of global warming and potentially dangerous environmental ramifications, Brassell said.\nThe conclusion does not address natural disasters, such as Hurricane Katrina or the 2004 Indian Ocean tsunami, but similar studies speculate the science of such events by analyzing storm deposits, Brassell said. \nThe team worked during the years that encompassed the production and release of "The Day After Tomorrow," a major motion picture that chronicled a fictionalized global warming catastrophe. Brassell said the sometimes-inaccurate film is relevant because its exaggerated "changing threshold" idea has some scientific basis, but he is assured that nothing of that nature will occur during our lifetime. \nShatsky Rise, a 3,101-meter-deep plateau east of Japan, was a useful field site for Brassell's group in 2001 because previous data were confined to the Atlantic Ocean. According to the paper, the addition of Pacific information implies "persistent or recurrent" oceanic instability in the Aptian era. \nReport co-author and Department of Geological Sciences Ph.D. candidate Mirela Dumitrescu secured research grants from IU and the Geological Society of America totaling about $5,000. The vessel used to gather samples was funded by the National Science Foundation. \nDespite the paper's pending publication, she will continue the project by observing fluctuations and relationships in populations with various conditions. Ending this segment of the research was "rewarding" for Dumitrescu in her quest for a Ph.D., but she said she looks forward to working more with Brassell and Dutch contributors Stefan Schouten, Ellen C. Hopmans and Jaap S. Sinninghe Damsté. The group will draw funding from an additional $80,000 grant recently awarded by the Petroleum Research Fund of the American Chemical Society. \nBrassell plans to continue his work in petroleum, microbial systems and climate patterns, despite teaching three undergraduate courses and instructing a graduate section. Conducting further research in global warming is a top priority for him and other geologists convinced of the problem's magnitude. "Of the 10 warmest years ever, nine of them were in the last decade," Brassell said.