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The Laboratory
in the News

Tree location important in carbon offset projects
A recent study by researchers from Lawrence Livermore, the Carnegie Institution, Stanford University, and Université Montpellier II in France found that tree location is an important factor when considering carbon offset projects. This study, funded in part by Livermore’s Laboratory Directed Research and Development Program, confirms that planting trees in the tropics could help slow global warming worldwide, but trees planted in mid to high latitudes could have the opposite effect. The research, led by Livermore atmospheric scientist Govindasamy Bala, appeared in the April 17, 2007, edition of the Proceedings of the National Academy of Sciences.
In general, forests affect climate in three ways. They help cool the planet by absorbing carbon dioxide and evaporating water to the atmosphere. Because they are dark, they also warm the planet by absorbing sunlight, a process referred to as the albedo effect. The collaboration’s research found in the tropics the convective clouds that form when trees absorb carbon dioxide cool the planet. In mid- to high-latitude areas, the albedo effect is more prevalent. Deforestation in these areas may cause regional temperatures to be as much as 10 degrees cooler than they would be with the forests.
The authors warn, however, that deforestation in mid- to high-latitude areas will not alleviate global warming. In fact, destroying these important ecosystems would be counterproductive because they provide many benefits, including natural habitats, biodiversity, economically valuable timber, watershed protection, and indirect prevention of ocean acidification.
Contact: Govindasamy Bala (925) 423-0771 (bala1@llnl.gov).

Study shows global warming effects on cereal crop yields
Livermore researcher David Lobell and Christopher Field from the Carnegie Institution researched the degree to which global food production has been affected by climate change. Their work, which was published in the March 16, 2007, issue of Environmental Research Letters, concluded that, on average, global crop yields respond negatively to warmer temperatures for several of the crops used in the study.
Lobell and Field studied climate effects on the six most widely grown cereal crops in the world—wheat, rice, maize (corn), soybeans, barley, and sorghum. These crops account for more than 40 percent of nonmeat calories in the human diet and more than 70 percent of animal feed. Between 1981 and 2002, the combined output of cereal crops throughout the world decreased by 40 million metric tons per year because of warming temperatures.
Using data from 1961 to 2002 provided by the Food and Agriculture Organization, Lobell and Field compared global crop yields with average temperatures and precipitation over the major growing regions. They then used the data to estimate the effect of the warming trends. For this study, the researchers assumed that farmers had not yet found methods for adapting crops to the temperature shift, such as planting crops that grow better in warmer climates. Their results indicate that yields have dropped approximately 3 to 5 percent for each 1-degree increase in temperature and that farmers must plant crops better suited for warmer climates to maintain sustainable production levels.
Contact: David Lobell (925) 422-4148 lobell2@llnl.gov.

Researchers gain insight into nuclear isomer decay
A collaboration led by Livermore researchers has moved one step closer to turning on and off the decay of a nuclear isomer—a key capability for using isomers as high-energy-density storage systems such as batteries. The research team, which included scientists from Los Alamos National Laboratory and the National Aeronautics and Space Administration’s Goddard Space Flight Center, studied an isomer of thorium-229 (229Th). Because the excitation energy for 229Th is near the energy level for laser light, scientists may one day be able to use a tabletop laser to transition 229Th nuclei between its ground and isomeric states. Developing that capability could lead to scientific breakthroughs such as a clock with unparalleled precision for general relativity tests; a superb qubit, or quantum bit, for quantum computing; and diagnostic tests to determine how nuclear decay rates affect the chemical environment.
However, before researchers can attempt such exotic studies, they must precisely measure the isomer’s excitation energy above the ground state. In the current study, the collaborative team used an indirect technique to make the most accurate measurement to date of the difference between the two states. According to Livermore physicist Bret Beck, who leads the project, the next step will be to tune a laser to the exact energy of the spacing so the transition can be observed directly. If that technique proves successful, researchers can focus on helping a transition from the excited isomeric state to the ground state—a process that gives off energy. Results from the team’s research appeared in the April 6, 2007, issue of Physical Review Letters.
Contact: Bret Beck (925) 423-6148 (beck6@llnl.gov).

Laboratory joins California Hazards Research Institute
As California’s population grows, so does the threat that natural hazards—earthquakes, tsunamis, volcanic eruptions, wild fires, floods, storms, and droughts—could turn into major catastrophes. The Laboratory is collaborating with 10 University of California (UC) campuses and 3 national laboratories to form the California Institute for Hazards Research (CIHR), a multicampus research program that will focus on all aspects of disaster research, planning, and preparedness.
CIHR will collaborate with state, federal, and international organizations on natural disaster research and education. It will encourage partnerships across the UC system and integrate them into an overall strategic plan. Research areas will include understanding and forecasting natural hazards, reducing the effect of natural disasters, strengthening emergency-response and public health systems, and improving long-term recovery and rebuilding.
John Rundle, director of the UC Davis Center for Computational Science and Engineering, leads the recently approved institute. According to Livermore geophysicist Doug Rotman, who leads the Laboratory’s work for the institute, the range of capabilities offered by the UC campuses and national laboratories will allow CIHR to comprehensively address hazards that threaten California. Livermore will contribute its expertise in chemistry, physics, atmospheric science, and national security to this collaborative effort.
Contact: Doug Rotman (925) 422-7746 (rotman1@llnl.gov).

Understanding the Pacific Ocean’s Ring of Fire
Laboratory scientist Megan Flanagan is working with UC Santa Cruz researchers to uncoil the geophysical and geochemical mysteries of the Pacific Ocean’s Ring of Fire. This 40,000-kilometer-long area of frequent earthquakes and volcanic eruptions results in a nearly continuous series of oceanic trenches, island arcs, and volcanic mountain ranges and plate movements. Ninety percent of the world’s earthquakes and 81 percent of the largest ones occur along the Ring of Fire.
By looking at earthquakes deep in the Pacific plate’s lithosphere (the outer shell of Earth’s mantle), Flanagan and her colleagues developed a three-dimensional model of the highest velocity primary and secondary waves moving through a subsurface area called the Tonga subduction zone. The zone is located between the Pacific plate and the northeastern corner of the Australian plate. When the Pacific plate subducts beneath the Australian plate, the overlying mantle wedge (the Tonga wedge) undergoes localized partial melting and ascent of magmas. As a result, island or continental arcs are produced.
The Pacific plate has been sinking at the Tonga subduction zone for 40 million years at a rate of about 15 centimeters per year. However, the northern portion has the fastest plate velocity recorded on the planet, sinking 25 centimeters per year. Using seismic waves from deep earthquakes in this region, the research team illustrated the structural and chemical complexity of the wedge. Their research, which appeared in the May 11, 2007, edition of Science, demonstrated the structure and processes essential for understanding the flow pattern of mantle material in the Tonga wedge. New images will also help researchers characterize the wedge dynamics and chemistry in this area.
Contact: Megan Flanagan (925) 422-3945 (flanagan5@llnl.gov).



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UCRL-52000-07-7/8 | July 18, 2007