Life Flourished When Earth Was Warmer, Scientist Says
The threat of a global warming doesn't scare Judith Parrish, a geologist at The University of Arizona in Tucson and an expert on ancient climates.
She's seen the ghost of the distant past in fossil leaves from the mid-Cretaceous, about 100 million years ago. These long-dead leaves tell tales of a warmer climate, when forests grew in the now-barren polar regions.
"Life flourished when the climate was warmer," said Parrish, UA professor of geosciences. Her book, "Interpreting Pre-Quaternary Climate from the Geologic Record," is being released this month. The Quaternary represents roughly the last 2 million years, a time of recurring ice ages when continental glaciers sometimes stretched as far south as Illinois.
"The last 2 million years don't have anywhere near the full range of climate history," Parrish emphasized. "The lack of ice during the Cretaceous is typical. Having the great big ice caps is not typical."
The Cretaceous describes the period 113 million to 65 million years ago, when dinosaurs roamed the planet. Geological evidence indicates that during the Cretaceous, as during much of the Earth's history, the planet was much warmer than it is today -- and generally warmer than it is projected to be in the next few centuries as the result of a buildup in greenhouse gases.
http://www.sciencedaily.com/releases/1998/10/981015080740.htm
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An Ancient Greenhouse Window Into The Future
Dr Patrick Moss, a lecturer in physical geography with the School of Geography, Planning and Architecture, is working on a research project that is unearthing what the world's climate was like 50-million-years-ago.
"We have been looking at how plants respond to warmer temperatures to give us an insight into what might happen if the Earth's temperatures continue to increase," Dr Moss said.
Dr Moss's research has focused on a particular area of western-Canada, where fossilised leaves, insects and pollen are revealing a vastly different landscape to that of today.
"50 million years ago western Canada was a sub-tropical rainforest," he said.
"We are finding evidence of palms as well as a mix of oak and redwood forests.
"And we have found a particular species of redwood that is now only found in a certain part of China."
He said the site in Canada was chosen because of such well-preserved fossil plants and insects as well as being at a similar latitude now as it was 50-million-years-ago, making it perfect for comparison with today's environment.
http://www.sciencedaily.com/releases/2007/02/070222180019.htm
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The Past Says Abrupt Climate Change In Our Future
"When we look at records of the past, climate often changed abruptly rather than smoothly," says Dr. Richard B. Alley, the Evan Pugh professor of geosciences at Penn State. "This is true wherever and whenever you look."
Alley, who is currently chairing the National Academy of Science Committee on Abrupt Climate Change: Science and Public Policy, told attendees today (Dec. 13) at the fall meeting of the American Geophysical Association in San Francisco, that while studies of ice cores, sediments and other relics of the past indicate these abrupt changes, the models currently used by those predicting the future of climate change do not do a good job of simulating abrupt changes in the past.
"If we look at what we know about climate, there is much we don't understand," says Alley. "However, we do know that abrupt change occurred in the past."
The abrupt changes are especially notable in temperature near the north and south poles and in precipitation away from the poles. In the near term, nature sometimes changes smoothly, sometimes remains the same and sometimes changes all at once. In the long term, abrupt change appears to be the norm. Current models all tend to change smoothly and do not capture abruptness.
"It is possible that climate change in the future will include abruptness, even though the current models do not show this," says Alley.
The Penn State geoscientist suggests that climate change includes a process of approaching and crossing a series of thresholds. Climate forcing factors are like a tower of blocks. Building the tower, blocks can be added, and the tower remains stable, but eventually the block height crosses the threshold of stability and the tower abruptly topples.
With climate, the thresholds in the past have sometimes been reached in as few as 10 years.
http://www.sciencedaily.com/releases/2001/12/011214081853.htm
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Overconfidence Leads To Bias In Climate Change Estimations
Just as overconfidence in a teenager may lead to unwise acts, overconfidence in projections of climate change may lead to inappropriate actions on the parts of governments, industries and individuals, according to an international team of climate researchers.
"One key question is which scenario is likely, which is less likely and which they can neglect for practical purposes," says Keller who is also affiliated with the Penn State Institutes of Energy and the Environment. "At the very least, the scenarios should span the range of relevant future outcomes. This relevant range should also include low-probability, high-impact events."
The researchers provide evidence that the current practice neglects a sizeable fraction of these low probability events and results in biased outcomes. Keller; Louis Miltich, graduate student; Alexander Robinson, Penn State research assistant now on a Fulbright Fellowship in Berlin, and Richard Tol, senior research officer, Economic and Social Research Institute, Dublin, Ireland, developed an Integrated Assessment Model to derive probabilistic projections of carbon dioxide emissions on a century time scale. Their results extended far beyond the range of previously published scenarios, the researchers told attendees today (Dec. 15) at the fall meeting of the American Geophysical Union in San Francisco.
The National Science Foundation supported this work.
http://www.sciencedaily.com/releases/2006/12/061215122457.htm
Gokul said:
Yet the only link you provided is the personal website of an engineer in the coal mining industry who has no background in climatology
He doesn't need a background in climatolgy to discuss the
geological records. That piece I posted was, as I said, a short synopsis of that geological time period. It is well known fact.