"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," explains Douglas S. Wilson of the University of California at Santa Barbara (UCSB), first author of the new work.
He and his UCSB co-author Bruce Luyendyk conclude that, contrary to most current models for bedrock elevations of West Antarctica, the region's bedrock in the past was at much higher elevation and covered a much larger area than today. Those 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 find 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.
In the existing theory, the low elevation of West Antarctica relegates it to a minor role in the ice accumulation that began 34 million years ago; ice sheets grew on the higher and larger East Antarctic subcontinent. West Antarctica only joined the process around 14 million years ago.
"But a problem exists with leaving West Antarctica out of the early ice history," says 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."
Evidence for that large mass of ice comes from two sources: One is geologic records of lowered sea level at the time, which indicate how much ice formed on land to produce the sea-level drop. The other is shells of marine microfossils which have chemical and isotopic compositions that are sensitive to ocean temperatures and to the amount of ice on land.
By showing that West Antarctica had a higher elevation 34 million years ago than previously thought, the new study reveals a possible site for the accumulation of the early ice that had been unaccounted for. Moreover, "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," says 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 adds.
The new hypothesis may solve another conflict among climate scientists. Given that more ice grew than could be hosted on East Antarctica alone, some researchers have proposed that the missing ice formed in the northern hemisphere. This would have been many millions of years before the well-known documentation of ice growth there, which started about 3 million years ago; evidence for ice sheets in the northern hemisphere prior to that time is not established. The new bedrock model shows it is not necessary to have ice hosted in the northern polar regions at the start of global climate transition; West Antarctica could have accommodated the extra ice.
The National Science Foundation's Office of Polar Programs funded this research.Title:
Bruce P. Luyendyk: Department of Earth Science and Institute for Crustal Studies, University of California, Santa Barbara, California, USA.Contact information for authors:
email@example.comBruce Luyendyk, Professor, Department of Earth Science, Tel: +1 (805) 893-405,
Peter Weiss | American Geophysical Union
Fossil coral reefs show sea level rose in bursts during last warming
19.10.2017 | Rice University
NASA finds newly formed tropical storm lan over open waters
17.10.2017 | NASA/Goddard Space Flight Center
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
17.10.2017 | Event News
10.10.2017 | Event News
10.10.2017 | Event News
19.10.2017 | Materials Sciences
19.10.2017 | Materials Sciences
19.10.2017 | Physics and Astronomy