Western River Basin Sensitivity to Climate Change Studied Region by Region
U11D-06 • Monday, Dec. 14, 9:15 a.m. • 103 Moscone South
Recent hydrologic modeling advances have given climate scientists the ability to more accurately pinpoint the implications of climate change across specific regions. Tapash Das, David Pierce, Dan Cayan and Mike Dettinger of Scripps Institution of Oceanography at UC San Diego are exploiting these advances to explore the sensitivities of river water runoff to changes in temperature and precipitation across the Western United States.
They found that total streamflow decreases in major Western U.S. rivers vary from as little as 1 percent per degree Celsius of climate warming to as much as 7 percent per degree Celsius. They say flow from California's Sierra Nevada rivers are not as sensitive to warming as the Colorado and Pacific Northwest river basins.
Warming conditions carry the greatest influence, they found, at locations with significant snow but that lie close to the freezing point.
"Our hope is to drill down and be able to inform city planners and water managers whether their region is likely to be more or less sensitive to climate change," said Pierce. "This information could help them plan for future conditions."
Das says new studies will factor in changes across the seasons with the goal of gauging sensitivities to warming in various months.
PRESENTATION TITLE: "SENSITIVITY OF RUNOFF TO CLIMATE WARMING OVER THE WESTERN U.S."
C12A-06 • Monday, Dec. 14, 11:35 a.m. • 3014 Moscone West
Glaciologists are using icequakes to better understand how glacier calving contributes to global sea-level rise. A Scripps Institution of Oceanography at UC San Diego-led research team is capturing seismic data from quakes that occur when icebergs detach in an effort to measure the size of calving events over time.
Scripps postdoctoral researcher Fabian Walter will present visual and seismic measurements from tidewater calving at Alaska's Columbia Glacier as well as calving of the Amery Ice and Ross Ice shelves in Antarctica. Glacier ice is the largest reservoir of fresh water on Earth.
Scientists believe that calving plays a key role in the glacial contribution to rising sea level, which, according to the 2007 Intergovernmental Panel on Climate Change (IPCC) fourth scientific assessment, is expected to rise 1.0 to 1.4 m (3.2-4.5 feet) by 2100. Recent advances in seismic signal processing now allow researchers to continuously monitor a glacier's calving activity.
"This quantitative description of calving will allow researchers to more accurately model glacier mass loss," said Walter. Researchers hope this information will be incorporated into ice sheet models to estimate future progression of ice sheet melting.
PRESENTATION TITLE: "ICEQUAKE TREMORS DURING GLACIER CALVING
Locating Earth's "Hum"
S21D-05 • Tuesday, Dec. 15, 9 a.m. • 2007 Moscone West
S51D-01 • Friday, Dec. 18, 8 a.m. • 2005 Moscone West
Scientists at Scripps Institution of Oceanography at UC San Diego have used data from the USArray Earthscope's transportable seismic network to pinpoint the Pacific coast of Central America as the source region of Earth's "hum," subsonic noise too low for humans to hear.
Peter Gerstoft and Peter Bromirski of Scripps say the hum, at frequencies between two and 15 millihertz, is generated by storm-driven waves traveling along the West Coast of the United States that are transformed to hum-generating "infragravity" waves (very long period waves).
Although the hum was detected more than a decade ago, the source was initially thought to result from atmospheric disturbances. Gerstoft and Bromirski have described an ocean-wave path that starts with storms over the deep ocean that generate swell. In addition to the Central American coast, the western coasts of North America and Europe also are important hum source regions.
"This gives us an indication of the amount of wave energy that is impacting coasts," said Bromirski. "There are also potential uses for investigating crustal and upper mantle structure once these signals are better understood."
"In addition to hum, we show that body-wave double-frequency microseisms are generated in the deep ocean under distant storms, and propagate through the earth's mantle and core..." said Gerstoft.
Some of the coastal infragravity wave energy leaks off the West Coast continental shelf and propagates to Antarctica, where it impacts the Ross Ice Shelf. This establishes a climate connection between storm activity in the North Pacific and possible destabilization of the Ross Ice Shelf, with implications affecting the rate of sea-level rise.
PRESENTATION TITLES: "ARRAY PROCESSING FOR OBSERVING EARTH'S 'HUM'" AND MICROSEISMS" AND "ATMOSPHERE -> OCEAN WAVES -> SEISMIC SIGNALS: SOLID EARTH - CLIMATE CONNECTIONS"
A Field in Flux: Earth's Magnetic Field
GP23A-0780 • Tuesday, Dec. 15, 1:40-6 p.m. • Poster Hall, Moscone South
An interdisciplinary study combining geophysics and archaeology uncovered new details of Earth's magnetic field strength during the early Iron Age, from 12th-9th centuries BCE. The study's results provide historic background on the debate as to whether Earth's magnetic field is heading toward a full reversal.
Scripps Institution of Oceanography at UC San Diego professor of geophysics Lisa Tauxe will present results from a recent study that analyzed magnetic field records contained in historical biblical artifacts collected from southern Levant region, the modern day border region of Jordan and Israel.
The research team analyzed copper-mining slag, a by-product left behind from the melting of copper ore to reveal a previously unknown spike in magnetic field strength. The results suggest that the current weakening of the geomagnetic field's strength is modest compared with historic fluctuations and indicate that the current drop could be an ordinary part of geomagnetic field fluctuations.
Earth's magnetic field has been steadily weakening since 1845, when scientists began tracking it. Its strength has waxed and waned throughout Earth's history and sometimes, at its weakest moments, has reversed in polarity. Reversals happen at random intervals, and the last full reversal occurred 780,000 years ago, which suggests the next one is overdue.
The research team includes Erez Ben-Yosef and Thomas E. Levy from UC San Diego's Department of Anthropology, Ron Shaar and Hagai Ron from the Hebrew University of Jerusalem's Institute of Earth Sciences in Israel and Mohammad Najjar of the Friends of Archaeology and Heritage Society in Jordan.
For more information on Tauxe's research, including images and podcast, visit Scripps explorations e-magazine: http://explorations.ucsd.edu/Features/2008/Heading_Due_South/
PRESENTATION TITLE: "GEOMAGNETIC INTENSITY SPIKE RECORDED IN HIGH RESOLUTION SLAG DEPOSITS IN SOUTHERN JORDAN"
Air Quality and Climate Change in California
A41D-0148 • Thursday, Dec. 17, 8 a.m.-12:20 p.m. • Poster Hall, Moscone South
New climate research suggests that the "lid" forming over Southern California and the San Joaquin Valley will strengthen to amplify the regions' already poor air quality as temperatures increase due to global climate change.
Scientists at Scripps Institution of Oceanography at UC San Diego analyzed weather balloon data of air temperature from 1960-2007 and Global Historical Climatology Network surface weather station observations to estimate future low-level air temperatures inversions at two of the nation's poorest air quality basins, the Southern California air basin and the San Joaquin Valley air basin.
Low-level temperature inversions occur when temperature increases with atmospheric height, a process that inhibits vertical motion in the lower atmosphere and leads to pollution buildup. Temperature inversions are a persistent climate feature throughout California that produce a "lid" that traps air pollutants over the air basins. Stronger temperature inversions have a thicker vertical extent and are linked to poor air quality.
The inversions studies drawn from climate model simulations over a 100 year period, from 2000-2100, indicate that the temperature inversion "lid" may strengthen as climate changes occur during the 21st century. The changes contained in the simulations would further inhibit ventilation and the ability to lift and export the pollutants out of California's basins.
The already abundant levels of air pollution in these basins result from large sources of urban and agricultural pollutants within the mountainous regions, which restricts air movement and limits its ventilation of accumulated pollution.
"The climate change problem adds to the incentives for a better understanding of the meteorological characteristics such as low-level inversions, that permit pollutants to build up," said Dan Cayan, Scripps climate scientist.
The Scripps research team includes climate researcher Sam Iacobellis, associate professor Joel Norris, researcher Masao Kanamitsu, research analyst Mary Tyree and Dan Cayan.
PRESENTATION TITLE: "FUTURE CHANGES IN LOW-LEVEL TEMPERATURE INVERSION IN CALIFORNIA"
Ocean Productivity Following Massive Extinction Event
PP41A-1479 • Thursday, Dec. 17, 8 a.m.-12:20 p.m. • Poster Hall, Moscone South
One of the mysteries of a mass extinction experienced on the planet 65.5 million years ago is how long Earth's ecosystems were knocked off kilter. Some research suggests that the oceans nearly "died" for as much as several hundred thousand years, whereas other studies suggest a much more rapid recovery of biological activity in the oceans.
Pincelli Hull, Richard Norris and Peter Franks of Scripps Institution of Oceanography at UC San Diego are investigating details of the production of organisms in the surface waters of the world's oceans after the extinction event. The remains of algae that grow in the surface ocean sink to the ocean floor-a process called "export productivity"-and are preserved in deep-ocean sediments. These sediments have been churned by burrowing organisms requiring that the researchers "unmix" the record using mathematical techniques to reconstruct the detailed history of biological production.
Hull and her fellow researchers find that the decrease in open ocean biological activity after the extinction was very widespread, but can differ greatly in magnitude and duration throughout the world's oceans.
PRESENTATION TITLE: "THE BIOGEOGRAPHY OF EXPORT PRODUCTIVITY ACROSS THE CRETACEOUS-PALEOGENE BOUNDARY AS INFERRED FROM SEDIMENT MIXING AND BIOGENIC BARIUM"
At AGU: Annie Reisewitz
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Scripps Institution of Oceanography at the University of California San Diego, is one of the oldest, largest, and most important centers for global science research and education in the world. Now in its second century of discovery, the scientific scope of the institution has grown to include biological, physical, chemical, geological, geophysical, and atmospheric studies of the earth as a system. Hundreds of research programs covering a wide range of scientific areas are under way today on every continent and in every ocean. The institution has a staff of more than 1,400 and annual expenditures of approximately $195 million from federal, state, and private sources. Scripps operates oceanographic research vessels recognized worldwide for their outstanding capabilities. Equipped with innovative instruments for ocean exploration, these ships constitute mobile laboratories and observatories that serve students and researchers from institutions throughout the world. Birch Aquarium at Scripps serves as the interpretive center of the institution and showcases Scripps research and a diverse array of marine life through exhibits and programming for more than 430,000 visitors each year. Learn more at scripps.ucsd.edu and follow us at Facebook, Twitter, and Instagram.
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