"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
Predicting unpredictability: Information theory offers new way to read ice cores
07.12.2016 | Santa Fe Institute
Sea ice hit record lows in November
07.12.2016 | University of Colorado at Boulder
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
07.12.2016 | Health and Medicine
07.12.2016 | Life Sciences
07.12.2016 | Health and Medicine