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ODP scientists say no large Northern Hemisphere ice sheets 41 million years ago
August 23, 2007New research to test global ice volume approximately 41.6 million years ago shows that ice caps at this time, if they existed at all, would have been small and easily accommodated on Antarctica.
The findings contradict a recent controversial suggestion that Earth was extensively glaciated at this time despite having been much warmer than today, most likely because of high atmospheric carbon dioxide levels. In an article published in Nature on 23 August, researchers using pinhead-sized fossils (foraminifera) - collected from sediments deep beneath the Atlantic Ocean, 380 km north of Suriname, South America - say large continental ice sheets did not exist in both hemispheres around 41 million years ago. Ocean Drilling Program (ODP) Expedition 207 explored and sampled the Central Atlantic's Demerara Rise in January and February of 2003.
This result is more in keeping with other geological records and climate model results suggesting that the threshold for ice sheet inception would have been crossed earlier in the Southern Hemisphere than in the Northern Hemisphere because the South Pole has a continent sitting over it (Antarctica) whereas the North Pole has an ocean (the Arctic).
Paul Wilson, lead proponent of ODP Expedition 207 explained, "The beauty of the new results is that they resolve a big problem. How can there have been more ice than today during an interval that was much warmer than today? The answer is that there was not more ice - that idea was a mistake based on inadequate data. The results give us renewed confidence in our understanding of the sequence of geological events and thus the controls on ice sheet existence." Wilson is on the faculty of the School of Ocean & Earth Science at the UK's National Oceanography Centre, Southampton.
"The research is a classic example of the amazing way in which the Earth System is so intricately integrated," said co-proponent Dick Norris of University of California, San Diego, Scripps Institution of Oceanography. "Isn't it a marvelous thing that we can learn so much about the polar continental ice caps by examining tiny fossils that lived on the sea floor at the equator."
Joint Oceanographic Institutions
Paul Wilson, lead proponent of ODP Expedition 207 explained, "The beauty of the new results is that they resolve a big problem. How can there have been more ice than today during an interval that was much warmer than today? The answer is that there was not more ice - that idea was a mistake based on inadequate data. The results give us renewed confidence in our understanding of the sequence of geological events and thus the controls on ice sheet existence." Wilson is on the faculty of the School of Ocean & Earth Science at the UK's National Oceanography Centre, Southampton.
"The research is a classic example of the amazing way in which the Earth System is so intricately integrated," said co-proponent Dick Norris of University of California, San Diego, Scripps Institution of Oceanography. "Isn't it a marvelous thing that we can learn so much about the polar continental ice caps by examining tiny fossils that lived on the sea floor at the equator."
Joint Oceanographic Institutions
Ice Caps Current Events and Ice Caps News RSSWhen it comes to sea level changing glaciers, new NASA technique measures up
A NASA-led research team has used satellite data to make the most precise measurements to date of changes in the mass of mountain glaciers in the Gulf of Alaska, a region expected to be a significant contributor to global sea level rise over the next 50-100 years.
'Deadly dozen' reports diseases worsened by climate change
Health experts from the Wildlife Conservation Society today released a report that lists 12 pathogens that could spread into new regions as a result of climate change, with potential impacts to both human and wildlife health and global economies.
An accurate picture of ice loss in Greenland
Researchers from TU Delft joined forces with the Center for Space Research (CSR) in Austin, Texas, USA, to develop a method for creating an accurate picture of Greenland's shrinking ice cap.
GOCE Earth Explorer satellite to look at the Earth's surface and core
The European Space Agency is about to launch the most sophisticated mission ever to investigate the Earth's gravitational field and to map the reference shape of our planet - the geoid - with unprecedented resolution and accuracy.
Patagonian glacier yields clues for improved understanding of global climate change
A better understanding of climate variations at planetary scale is one of climate scientists' crucial concerns. Stable water isotope analysis, the chemistry of ice cores taken from the Arctic and Antarctic polar ice caps and of air bubbles trapped in them now allow a chronology to be drawn up of the climate changes that took place over the past 800 000 years.
Climate change and species distributions
Scientists have long pointed to physical changes in the Earth and its atmosphere, such as melting polar ice caps, sea level rise and violent storms, as indicators of global climate change.
Unravelling the 'inconvenient truth' of glacier movement
Predicting climate change depends on many factors not properly included in current forecasting models, such as how the major polar ice caps will move in the event of melting around their edges.
Ocean warming on the rise
Increased scientific confidence that ocean observations are accurately reflecting rising global temperatures is central to new Australian research published today in the journal, Nature.
Ocean temperatures and sea level increases 50 percent higher than previously estimated
New research suggests that ocean temperature and associated sea level increases between 1961 and 2003 were 50 percent larger than estimated in the 2007 Intergovernmental Panel on Climate Change report.
Evidence of glaciation in 'super greenhouse' world
Large ice-sheets existed on Earth about 91 million years ago, during one of the warmest periods since life began, an international team of scientists reports this week.
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