LONDON Pinhead-sized fossils buried deep under the ocean show that glaciers did not coat the poles 41 million years ago, a new study shows, disputing earlier research that suggested huge ice sheets covered the Earth's extremities.
Any glaciers then -- a time when the planet was much warmer -- would only have been in small areas in Antarctica's interior and not in the Northern hemisphere, said Paul Wilson, from Britain's National Oceanography Centre, who led the study.
Wilson's study contradicts research published in 2005 that suggested ice sheets covered much of both polar regions, despite the higher temperatures. He added that the fossils could provide clues to the future of climate change.
"Essentially their idea (in the earlier study) was a mistake based on inadequate data," he told Reuters of the previous study before his work appeared in the journal Nature.
Using the world's only ship capable of executing the research operation, Wilson's team drilled deep through sediment layers at the bottom of the Atlantic Ocean near Surinam for the fossils of single-celled animals called foraminifera. It then tested the chemistry of their tiny shells for signs of ice formation.
"The hard thing is getting hold of sediment 40 million years old to generate a record," he said.
In the period his team studied, the earth had about as much carbon dioxide in the atmosphere as scientists predict may be present in 100 years, so the findings also offer clues as to how rising greenhouse gas levels may affect the planet, Wilson said.
"In order to understand where we are headed you need to go a lot farther back in geologic history to encounter conditions we may face in the future," he said.
Greenhouse gases such as carbon dioxide are widely blamed for global warming. Scientists say average temperatures will rise by between 2-6 degrees Celsius (about 4-11 F) by the end of the century, causing droughts, floods and violent storms.
Our top photos from the past week.