Media Tip Sheet
Supraglacial lake drainage and dynamic ice sheet response
WHOI glaciologist Sarah Das and colleagues investigated modes of supraglacial lake drainage using geophysical, ground, and remote sensing observations over the western margin of the Greenland ice sheet. Lakes exhibit a characteristic life cycle defined by a pre-drainage, drainage, and post-drainage phase. In the pre-drainage phase winter snow fills pre-existing cracks and stream channels, efficiently blocking past drainage conduits. As temperatures increase in the spring, surface melting commences, initially saturating the snow pack and subsequently forming a surface network of streams that fills the lake basins. Basins continue to fill until lake drainage commences, which for individual lakes occurs at different times depending on the previous winter snow accumulation and summer temperatures. The researchers found that supraglacial lakes show a spectrum of drainage behaviors and that these styles of drainage lead to varying rates and timing of surface meltwater delivery to the bed resulting in different dynamic ice responses.
Presentation Title: Modes of supraglacial lake drainage and dynamic ice sheet response
Time of Presentation: Monday, Dec. 5, 1:40-1:55 p.m.
Location: 3011 Moscone West
Stress Lessons From Japan Earthquake
The March 11, 2011, Tohoku earthquake provides an unprecedented test of the extent to which stress transfer governs the triggering of aftershocks. The test is made feasible by the extraordinary quality and accessibility of the Japanese seismic and geodetic monitoring networks. WHOI geophysicist Jian Lin, who has studied extensively earthquake interaction around world will discuss what researchers have learned from analyzing the 2011 Japan earthquake and its many aftershocks. Lin and colleagues calculate that large sections of the Japan trench mega-thrust, outer trench slope normal faults, the Kanto fragment beneath Tokyo, and the Itoigawa-Shizuoka Tectonic Line, were brought closer to failure.
Presentation Title: Using the 2011 M=9.0 Tohoku earthquake to test the Coulomb stress triggering hypothesis and to calculate faults brought closer to failure
Time of Presentation: Tuesday, Dec. 6, 10:35-10:50 a.m.
Location: 2009 Moscone West
Warm Atlantic Waters in the Northeast Greenland Ice Stream
The Northeast Greenland Ice Stream—one of Greenland’s largest—stretches far inland and drains an area that is mostly below sea-level. The Nioghalvfjerdsfjorden, (or ‘79 North) Glacier is grounded 600 m below sea level and experiences substantial basal melting by warm Atlantic Waters circulating under its 80 km long floating ice tongue. Ocean warming at 79 North Glacier could lead to the thinning and disintegration of the tongue, which could result in a rapid retreat of the Northeast Greenland Ice Stream, with serious consequences for sea level rise. The ability to predict changes of the 79 North Glacier is strongly limited by the lack of measurements from this region. Fiamma Straneo, of the WHOI Physical Oceanography department, reports results from an oceanographic survey of properties under and around 79 North Glacier which clearly shows that relatively warm Atlantic waters flow under the floating ice tongue by gaps through the pinned front.
Presentation Title: Pathways, characteristics and variability of the warm Atlantic Water flowing under the 79 North Glacier of the Northeast Greenland Ice Stream
Time of Presentation: Tuesday, Dec. 6, 11:35-11:50 a.m.
Location: 3009 Moscone West
Old Carbon in the Ganges Brahmaputra Basin
WHOI researchers Valier Galy and Timothy Eglinton examined the radiocarbon content of river sediments collected from the Ganges-Brahmaputra system draining the Himalayas. The basin represents one of the largest sources of terrestrial biospheric carbon to the ocean. They found that organic carbon resides in the basin for anywhere from 500 to 17,000 years—a surprisingly long time, making it likely that global warming could destabilize the pool of carbon there and in similar places on Earth, potentially increasing the rate of CO2 released into the atmosphere.
Presentation Title: Protracted Storage of Biospheric Carbon In The Ganges‐Brahmaputra Basin
Time of Presentation: Wednesday, Dec. 7, 11:05-11:20 a.m.
Location: 2006 Moscone West
Ocean acidification & inorganic carbon system along the Gulf of Mexico and Atlantic Coast
During the summer of 2007, the inorganic carbon system of the Gulf of Mexico and the U.S. Atlantic Coast was comprehensively surveyed to obtain baseline conditions of the carbonate chemistry, inorganic carbon fluxes and associated biogeochemistry. Zhaohui Aleck Wang, of the WHOI Marine Chemistry & Geochemistry department, reports what researchers learned from the survey and the factors that indicate the northeastern U.S. coast may be more vulnerable to ocean acidification in the coming decades.
Presentation Title: The Marine Inorganic Carbon System along the Gulf of Mexico and Atlantic Coast of the United States: Shelf‐ocean exchange and Ocean Acidification Status
Time of Presentation: Thursday, Dec. 8, 10:50-11:05 a.m.
Location: 3007 Moscone West
Tropical ocean experiment: Coral calcification response to acidification
Much of our understanding of the impact of ocean acidification on coral calcification comes from laboratory experiments which rear corals under a range of conditions with seawater pH and aragonite saturation equivalent to those projected for the next hundred years. In general, experiments show a consistently negative impact on coral calcification, leading to predictions of mass coral reef extinctions by dissolution as natural rates of carbonate erosion exceed the rates at which corals and other reef calcifiers can replace it. The tropical oceans provide a natural laboratory in which to test hypotheses about the longer-term impacts and adaptive potential of corals to acidification. Anne Cohen, of WHOI, will report results of a Pacific-wide study that investigated the impact of acidification on corals in their natural reef environment.
Presentation Title: Coral Calcification Across a Natural Gradient in Ocean Acidification
Time of Presentation: Thursday, Dec. 8, 1:55‐2:10 p.m.
Location: 3007 Moscone West
Hurricane Activity in North Atlantic
Extreme storms pose a significant threat to lives and resources in heavily populated coastal regions. However, because of the relative rarity of intense hurricanes (>Category 3) making landfall and the shortness of the instrumental record, little is known about past patterns of intense hurricane activity. Using a series of high-resolution reconstructions of hurricane-induced overwash from high deposition rate sites from across the western North Atlantic, Jeffrey Donnelly, of the WHOI Geology & Geophysics department, and his colleagues documented patterns of hurricanes in the North Atlantic dating back more than 2000 years and resulting impacts on coastal lands and ecosystems.
Presentation Title: North Atlantic Tropical Cyclone Activity over the last 2000 years: Patterns, Consequences and Potential Climatic Forcing
Time of Presentation: Thursday, Dec. 8, 2:10-2:25 p.m.
Location: 3005 Moscone West