Glacier’s retreat is now irreversible

13 January 2014, by Harriet Jarlett

The work, published in Nature Climate Change, shows the glacier’s retreat may have begun an irreversible process that could see the amount of water it is adding to the ocean increase five-fold.

‘At the Pine Island Glacier we have seen that not only is more ice flowing from the glacier into the ocean, but it’s also flowing faster across the grounding line – the boundary between the grounded ice and the floating ice. We also can see this boundary is migrating further inland,’ says Dr G. Hilmar Gudmundsson from NERC’s British Antarctic Survey, a researcher on the project.

The team, which included scientists from the CSC-IT Center for Science in Finland, the Chinese Academy of Sciences and the Universities of Exeter and Bristol, used three computer models as well as field observations to study how the glacier’s ice flows and to simulate how this will change over the coming decades.

All the models agreed that the Pine Island Glacier has become unstable, and will continue to retreat for tens of kilometres.

‘The Pine Island Glacier shows the biggest changes in this area at the moment, but if it is unstable it may have implications for the entire West Antarctic Ice Sheet,’ says Gudmundsson. ‘Currently we see around two millimetres of sea level rise a year, and the Pine Island Glacier retreat could contribute an additional 3.5 – 5 millimeters in the next twenty years, so it would lead to a considerable increase from this area alone. But the potential is much larger.’
Pine Island Glacier currently contributes 25 per cent of the total ice loss from West Antarctica. If the entire West Antarctic Ice Sheet was to retreat, it could cause sea level to rise up to five metres.

‘The models show a strong agreement and the result is a striking vision of the near future. All the models suggest that this recession will not stop, cannot be reversed and that more ice will be transferred into the ocean,’ says Dr Gaël Durand of CNRS, Laboratoire de Glaciologie et de Géophysique de l’Environnement at the University of Grenoble, another researcher on the project.

Pine Island glacier.

Gudmundsson doesn’t believe that an iceberg the size of Manhattan, which broke off from the Pine Island Glacier last July, will have had any impact on the self-sustained retreat of the grounding line currently seen at the glacier.

‘Calving, where an iceberg breaks off from a glacier, does not contribute to sea level rise as the iceberg is already in the ocean so it will have already displaced any water it was going to,’ Gudmundsson explains.

Keywords: Antarctic, Climate system, Earth system, Environmental change, Geology, Ice, Oceans, Polar, Sea level change,

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Call For Higher Immigration Exposes Australian Frailty

SYDNEY, Jan 13 (Bernama) — A leading business lobby group has called for a jump in Australia’s migration intake, reigniting the debate that helped destroy former Prime Minister Kevin Rudd’s career and exposing the skills shortage that could skewer Australia’s transition from a mining dependent economy.

According to the Australian Bureau of Statistics, population in Australia will grow to between 34.3 and 41.9 million in 2050 and between 42.3 and 69.5 million in 2100.

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Contact: Franny White
franny.white@pnnl.gov
509-375-6904
DOE/Pacific Northwest National Laboratory

Battery development may extend range of electric cars

New anode quadruples life of lithium-sulfur battery, could also help store renewable energy more cheaply

		IMAGE: Pacific Northwest National Laboratory researchers have developed a hybrid anode made of graphite and lithium that could quadruple the lifespan of lithium-sulfur batteries. Click here for more information.

RICHLAND, Wash. – It’s known that electric vehicles could travel longer distances before needing to charge and more renewable energy could be saved for a rainy day if lithium-sulfur batteries can just overcome a few technical hurdles. Now, a novel design for a critical part of the battery has been shown to significantly extend the technology’s lifespan, bringing it closer to commercial use.

A “hybrid” anode developed at the Department of Energy’s Pacific Northwest National Laboratory could quadruple the life of lithium-sulfur batteries. Nature Communications published a paper today describing the anode’s design and performance.

“Lithium-sulfur batteries could one day help us take electric cars on longer drives and store renewable wind energy more cheaply, but some technical challenges have to be overcome first,” said PNNL Laboratory Fellow Jun Liu, who is the paper’s corresponding author. “PNNL’s new anode design is helping bringing us closer to that day.”

Today’s electric vehicles are commonly powered by rechargeable lithium-ion batteries, which are also being used to store renewable energy. But the chemistry of lithium-ion batteries limits how much energy they can store. One promising solution is the lithium-sulfur battery, which can hold as much as four times more energy per mass than lithium-ion batteries. This would enable electric vehicles to drive longer on a single charge and help store more renewable energy. The down side of lithium-sulfur batteries, however, is they have a much shorter lifespan because they can’t be charged as many times as lithium-ion batteries.

Most batteries have two electrodes: one is positively charged and called a cathode, while the second is negative and called an anode. Electricity is generated when electrons flow through a wire that connects the two. Meanwhile, charged molecules called ions shuffle from one electrode to the other through another path: the electrolyte solution in which the electrodes sit.

The lithium-sulfur battery’s main obstacles are unwanted side reactions that cut the battery’s life short. The undesirable action starts on the battery’s sulfur-containing cathode, which slowly disintegrates and forms molecules called polysulfides that dissolve into the battery’s electrolyte liquid. The dissolved sulfur eventually develops into a thin film called the solid-state electrolyte interface layer. The film forms on the surface of the lithium-containing anode, growing until the battery is inoperable.

Most lithium-sulfur battery research to date has centered on stopping sulfur leakage from the cathode. But PNNL researchers determined stopping that leakage can be particularly challenging. Besides, recent research has shown a battery with a dissolved cathode can still work. So the PNNL team focused on the battery’s other side by adding a protective shield to the anode.

The new shield is made of graphite, a thin matrix of connected carbon molecules that is already used in lithium-ion battery anodes. In a lithium-sulfur battery, PNNL’s graphite shield moves the sulfur side reactions away from the anode’s lithium surface, preventing it from growing the debilitating interference layer. Combining graphite from lithium-ion batteries with lithium from conventional lithium-sulfur batteries, the researchers dubbed their new anode a hybrid of the two.

The new anode quadrupled the lifespan of the lithium-sulfur battery system the PNNL team tested. When equipped with a conventional anode, the battery stopped working after about 100 charge-and-discharge cycles. But the system worked well past 400 cycles when it used PNNL’s hybrid anode and was tested under the same conditions.

“Sulfur is still dissolved in a lithium-sulfur battery that uses our hybrid anode, but that doesn’t really matter,” Liu said. “Tests showed a battery with a hybrid anode can successfully be charged repeatedly at a high rate for more 400 cycles, and with just an 11-percent decrease in the battery’s energy storage capacity.”

This and most other lithium-sulfur battery research is conducted with small, thin-film versions of the battery that are ideal for lab tests. Larger, thicker batteries would be needed to power electric cars and store renewable energy. Liu noted tests with a larger battery system would better evaluate the performance of PNNL’s new hybrid anode for real-world applications.

This study was primarily supported by the Department of Energy’s Office of Science (BES), with additional support from DOE’s Advanced Research Projects Agency-Energy, and DOE’s Office of Energy Efficiency and Renewable Energy. Some of this research was performed at EMSL, DOE’s Environmental and Molecular Sciences Laboratory at PNNL.

REFERENCE: Cheng Huang, Jie Xiao, Yuyan Shao, Jianming Zheng, Wendy D. Bennett, Dongping Lu, Saraf V. Laxmikant, Mark Engelhard, Liwen Ji, Jiguang Zhang, Xiaolin Li, Gordon L. Graff & Jun Liu, Manipulating surface reactions in lithium-sulfur batteries using hybrid anode structures, Nature Communications, Jan. 9, 2014,DOI: 10.1038/ncomms/4015, http://dx.doi.org/10.1038/ncomms4015.

Interdisciplinary teams at Pacific Northwest National Laboratory address many of America’s most pressing issues in energy, the environment and national security through advances in basic and applied science. Founded in 1965, PNNL employs 4,300 staff and has an annual budget of about $950 million. It is managed by Battelle for the U.S. Department of Energy. For more information, visit the PNNL News Center, or follow PNNL on Facebook, Google+, LinkedIn and Twitter.

The Department of Energy’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time.

EMSL, the Environmental Molecular Sciences Laboratory, is a national scientific user facility sponsored by the Department of Energy’s Office of Science. Located at Pacific Northwest National Laboratory in Richland, Wash., EMSL offers an open, collaborative environment for scientific discovery to researchers around the world. Its integrated computational and experimental resources enable researchers to realize important scientific insights and create new technologies

Giant Antarctic glacier beyond point of no return

Monday, 13 January 2014
AFP

An aerial view of a crack at the Pine Island Glacier ice shelf seen in western Antarctica (Reuters: Goddard Space Flight Center)

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Antarctica’s Pine Island Glacier, one of the biggest single contributors to world sea-level rise, is melting irreversibly and could add as much as a centimetre to ocean levels in 20 years, say scientists.

The glacier “has started a phase of self-sustained retreat and will irreversibly continue its decline,” says Gael Durand, a glaciologist with France’s Grenoble Alps University.

Durand and an international team used three different models to forecast the glacier’s future based on the “grounding line,” which is the area under water where the ice shelf – a sea-floating extension of the continent-covering ice sheet – meets land.

This line has receded by about 10 kilometres in the past decade.

The grounding line “is probably engaged in an unstable 40 kilometre retreat,” according to the study, published in the journal Nature Climate Change.

A massive river of ice, the glacier by itself is responsible for 20 per cent of total ice loss from the West Antarctic Ice Sheet today.

On average, it shed 20 billion tonnes of ice annually from 1992-2011, a loss that is likely to increase up to and above 100 billion tonnes each year, the study’s authors write.

This is equivalent to 3.5 to 10 millimetres of global average sea-level rise over the next 20 years.

The global mean sea level rose by 3.2 millimetres in 2010 – itself a near-doubling from the rate of two decades earlier.

The European Space Agency said last month that the West Antarctic ice sheet was shedding ice at a much faster rate than before – currently at about 150 cubic kilometres per year.

Climate scientists are keeping a worried eye on the mighty ice sheets of Greenland and Antarctica, as continued losses could threaten vulnerable coastal cities with dangerously high sea levels.

Last year, the United Nations’ climate science body, the Intergovernmental Panel on Climate Change (IPCC) projected sea levels would rise between 26 and 82 centimetres by 2100.