Location for lost ice sheet proposed in Atlantic
Washington: A new research by scientists at UC (University of California) Santa Barbara indicates a possible Antarctic location for ice that seemed to be missing at a key point in climate history 34 million years ago.
“Using data from prior geological studies, we have constructed a model for the topography of West Antarctic bedrock at the time of the start of the global climate transition from warm ‘greenhouse’ earth to the current cool ‘icehouse’ earth some 34 million years ago," explained Douglas S. Wilson, first author and an associate research geophysicist with UCSB’s Department of Earth Science and Marine Science Institute.
Wilson and his co-author, Bruce Luyendyk, a professor in the Department of Earth Science, discovered that, contrary to most current models for bedrock elevations of West Antarctica, the bedrock in the past was of much higher elevation and covered a much larger area than today.
Current models assume that an archipelago of large islands existed under the ice at the start of the climate transition, similar to today, but Wilson and Luyendyk found that does not fit their new model.
In fact, the authors state that the land area above sea level of West Antarctica was about 25 percent greater in the past.
The existing theory leaves West Antarctica in a minor role in terms of the ice accumulation beginning 34 million years ago.
Ice sheet growth on earth is believed to have developed on the higher and larger East Antarctic subcontinent while West Antarctica joined the process later around 14 million years ago.
“But a problem exists with leaving West Antarctica out of the early ice history,” said Wilson.
“From other evidence, it is believed that the amount of ice that grew on earth at the 34 million year climate transition was too large to be accounted for by formation on East Antarctica alone, the most obvious location for ice sheet growth. Another site is needed to host the extra missing ice,” he said.
The new study, by showing that West Antarctica had a higher elevation 34 million years ago than previously thought, reveals a possible site for the accumulation of the early ice that is unaccounted for.
“Preliminary climate modeling by researchers at Pennsylvania State University demonstrates that this new model of higher elevation West Antarctica bedrock topography can indeed host the missing ice,” said Luyendyk.
“Our results, therefore, have opened up a new paradigm for the history of the growth of the great global ice sheets. Both East and West Antarctica hosted the growing ice,” he added.