Images of areas below the Eastern Ross Sea, next to West Antarctica, provide evidence that the subcontinent was involved in the general growth of the Antarctic Ice Sheet as it formed many millions of years ago, according to scientists at the University of California, Santa Barbara. The National Science Foundation provided funding for the project.
Changes in Antarctica, an area that contains approximately 90 percent of the world's ice, are particularly important for understanding some implications of global warming. For example, melting of ice sheets –– due to warming of the atmosphere and oceans –– has emerged as a key factor in the modeling of climate scenarios. And as ice melts, habitat for penguins and other marine animals also decreases.
Most studies of the "greenhouse to icehouse transition" –– a time of climatic change that occurred about 35 million years ago –– deal only with ice sheet growth on East Antarctica, according to the scientists. They do not recognize the ice sheet on West Antarctica. The current time is referred to as "icehouse" because it is a comparatively cool period in the Earth's history.
"We know that West Antarctica is the most sensitive of the ice sheets and most likely to respond adversely to global warming," commented Bruce Luyendyk, professor of marine geophysics and Earth science at UC Santa Barbara, and co-author of a paper describing the study in the May issue of the journal Geology.
Much of the bedrock of West Antarctica is underwater, making the ice sheets that cover it particularly vulnerable to slipping into the ocean as it warms, which will cause sea levels to rise. West Antarctica, a very large subcontinent with a peninsula that reaches toward Southern Chile, has about 2.5 million cubic kilometers of ice sitting on it.
The scientific team believes that West Antarctica was previously higher in elevation, and that large glaciers extended offshore into the Ross Sea from the Marie Byrd Land sector of West Antarctica prior to 25 million years ago.
The scientists used seismic reflection imaging, a type of echo-sounding that shows structures hundreds of meters beneath the ocean floor. The images depict geological structures underneath the Eastern Ross Sea.
"These seismic reflection profiles image U-shaped, erosional troughs that are interpreted as having been carved by glaciers, and flat-topped ridges, that are interpreted as giant moraines," said first author Christopher C. Sorlien, a research scientist at UCSB. Moraines are large mounds of sediment that have been deposited by moving glaciers.
These features mapped below the sea floor look like formations carved and deposited by glaciers elsewhere. "We can see that ice was carving up the continental shelf soon after the greenhouse to icehouse transition," said Luyendyk. "These look like geological features that were formed by moving ice."
This evidence for West Antarctica participating in the general growth of the Antarctic Ice Sheet has not been demonstrated before now in areas adjacent to the continent, he explained. "The significance of the findings is that much more of the continent was hosting an ice sheet at the start of ‘icehouse' Earth, than previously suspected."
In addition to Sorlien and Luyendyk, other co-authors from UCSB are Douglas S. Wilson, an associate research geophysicist in the Department of Earth Science, and Robert C. Decesari, who was a research assistant in the same department and is now a senior petroleum geologist with Exxon Mobil. Louis R. Bartek, associate professor in the Department of Geological Sciences at the University of North Carolina, Chapel Hill, and John B. Diebold, a senior scientist at Columbia University's Lamont-Doherty Earth Observatory, are also co-authors.
Gail Gallessich | EurekAlert!
Stagnation in the South Pacific Explains Natural CO2 Fluctuations
23.02.2018 | Carl von Ossietzky-Universität Oldenburg
First evidence of surprising ocean warming around Galápagos corals
22.02.2018 | University of Arizona
A newly developed laser technology has enabled physicists in the Laboratory for Attosecond Physics (jointly run by LMU Munich and the Max Planck Institute of Quantum Optics) to generate attosecond bursts of high-energy photons of unprecedented intensity. This has made it possible to observe the interaction of multiple photons in a single such pulse with electrons in the inner orbital shell of an atom.
In order to observe the ultrafast electron motion in the inner shells of atoms with short light pulses, the pulses must not only be ultrashort, but very...
A group of researchers led by Andrea Cavalleri at the Max Planck Institute for Structure and Dynamics of Matter (MPSD) in Hamburg has demonstrated a new method enabling precise measurements of the interatomic forces that hold crystalline solids together. The paper Probing the Interatomic Potential of Solids by Strong-Field Nonlinear Phononics, published online in Nature, explains how a terahertz-frequency laser pulse can drive very large deformations of the crystal.
By measuring the highly unusual atomic trajectories under extreme electromagnetic transients, the MPSD group could reconstruct how rigid the atomic bonds are...
Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...
For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.
In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...
Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale
Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...
15.02.2018 | Event News
13.02.2018 | Event News
12.02.2018 | Event News
23.02.2018 | Physics and Astronomy
23.02.2018 | Health and Medicine
23.02.2018 | Physics and Astronomy