"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:
firstname.lastname@example.orgBruce Luyendyk, Professor, Department of Earth Science, Tel: +1 (805) 893-405,
Peter Weiss | American Geophysical Union
Water - as the underlying driver of the Earth’s carbon cycle
17.01.2017 | Max-Planck-Institut für Biogeochemie
Modeling magma to find copper
13.01.2017 | Université de Genève
Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).
Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...
10.01.2017 | Event News
09.01.2017 | Event News
05.01.2017 | Event News
18.01.2017 | Materials Sciences
18.01.2017 | Information Technology
18.01.2017 | Ecology, The Environment and Conservation