Guidry E.P.,University of Louisiana at Lafayette |
Richter C.,University of Louisiana at Lafayette |
Acton G.D.,University of California at Davis |
Channell J.E.T.,University of Florida |
And 4 more authors.
Geological Society Special Publication | Year: 2013
We present palaeomagnetic results from the Oligocene through Miocene part of the Integrated Ocean Drilling Program Site U1333 (1030.996'N, 138825.159'W), which is located in 4853 m-deep water over seafloor with an estimated crustal age of 46 Ma. Detailed magnetostratigraphic investigations are essential to provide a sound age model for the study of the palaeoclimatic and palaeo-oceanographic history of the Cenozoic of the Equatorial Pacific and to improve the database of Pacific magnetostratigraphy. Rock magnetic measurements were carried out at 1 cm resolution on 81 U-channel samples from the spliced section with the goal of extracting a high-resolution record of the magnetostratigraphy. Stepwise demagnetization of the natural remanent magnetization yielded a well-defined magnetostratigraphy over a time interval of approximately 10 Ma between the base of Chron C6n (19.722 Ma) and the middle of Chron C11r (>29.9 Ma) and identification of the Oligocene-Miocene transition at the base of Subchron C6Cn.2n. The palaeomagnetic data are characterized by shallow inclinations, and by 1808 alternations in declinations downhole, reflecting magnetic polarity zones. The relatively high temporal resolution allowed for the identification of three possible excursions previously not identified on the geomagnetic polarity time scale, which were recorded in Subchrons C8n.1r and C11n.2n and in Chron C11r. © The Geological Society of London 2013.
Abe-Ouchi A.,University of Tokyo |
Andersen M.,University of Bristol |
Antonioli F.,ENEA |
Bamber J.,University of Bristol |
And 28 more authors.
Journal of Quaternary Science | Year: 2010
Uncertainties in sea-level projections for the 21st century have focused ice sheet modelling efforts to include the processes that are thought to be contributing to the recently observed rapid changes at ice sheet margins. This effort is still in its infancy, however, leaving us unable to make reliable predictions of ice sheet responses to a warming climate if such glacier accelerations were to increase in size and frequency. The geological record, however, has long identified examples of nonlinear ice sheet response to climate forcing (Shackleton NJ, Opdyke ND. 1973. Oxygen isotope and paleomagnetic stratigraphy of equatorial Pacific core V28-239, late Pliocene to latest Pleistocene. Geological Society of America Memoirs 145: 449-464; Fairbanks RG. 1989. A 17,000 year glacioeustatic sea level record: influence of glacial melting rates on the Younger Dryas event and deep ocean circulation. Nature 342: 637-642; Bard E, Hamelin B, Arnold M, Montaggioni L, Cabioch G, Faure G, Rougerie F. 1996. Sea level record from Tahiti corals and the timing of deglacial meltwater discharge. Nature 382: 241-244), thus suggesting an alternative strategy for constraining the rate and magnitude of sea-level change that we might expect by the end of this century. © 2009 John Wiley & Sons, Ltd.
Banas N.S.,University of Strathclyde |
Zhang J.,Applied Physics Laboratory |
Campbell R.G.,University of Rhode Island |
Sambrotto R.N.,LDEO |
And 6 more authors.
Journal of Geophysical Research: Oceans | Year: 2016
A new planktonic ecosystem model was constructed for the Eastern Bering Sea based on observations from the 2007-2010 BEST/BSIERP (Bering Ecosystem Study/Bering Sea Integrated Ecosystem Research Program) field program. When run with forcing from a data-assimilative ice-ocean hindcast of 1971-2012, the model performs well against observations of spring bloom time evolution (phytoplankton and microzooplankton biomass, growth and grazing rates, and ratios among new, regenerated, and export production). On the southern middle shelf (57°N, station M2), the model replicates the generally inverse relationship between ice-retreat timing and spring bloom timing known from observations, and the simpler direct relationship between the two that has been observed on the northern middle shelf (62°N, station M8). The relationship between simulated mean primary production and mean temperature in spring (15 February to 15 July) is generally positive, although this was found to be an indirect relationship which does not continue to apply across a future projection of temperature and ice cover in the 2040s. At M2, the leading direct controls on total spring primary production are found to be advective and turbulent nutrient supply, suggesting that mesoscale, wind-driven processes - A dvective transport and storminess - may be crucial to long-term trends in spring primary production in the southeastern Bering Sea, with temperature and ice cover playing only indirect roles. Sensitivity experiments suggest that direct dependence of planktonic growth and metabolic rates on temperature is less significant overall than the other drivers correlated with temperature described above. © 2016. American Geophysical Union. All Rights Reserved.
Marjanovic M.,LDEO |
Carbotte S.M.,LDEO |
Nedimovi M.R.,LDEO |
Nedimovi M.R.,Dalhousie University |
Geochemistry, Geophysics, Geosystems | Year: 2011
Variations in topography and seismic structure are observed along the Juan de Fuca (JdF) Ridge axis and in the vicinity of pseudofaults on the ridge flanks left by former episodes of ridge propagation. Here we analyze gravity data coregistered with multichannel seismic data from the JdF Ridge and flanks in order to better understand the origin of crustal structure variations in this area. The data were collected along the ridge axis and along three ridge-perpendicular transects at the Endeavor, Northern Symmetric, and Cleft segments. Negative Mantle Bouguer anomalies of -21 to -28 mGal are observed at the axis of the three segments. Thicker crust at the Endeavor and Cleft segments is inferred from seismic data and can account for the small differences in axial gravity anomalies (3-7 mGal). Additional low densities/elevated temperatures within and/or below the axial crust are required to explain the remaining axial MBA low at all segments. Gravity models indicate that the region of low densities is wider beneath the Cleft segment. Gravity models for pseudofaults crossed along the three transects support the presence of thinner and denser crust within the pseudofault zones that we attribute to iron-enriched crust. On the young crust side of the pseudofaults, a 10-20 km wide zone of thicker crust is found. Reflection events interpreted as subcrustal sills underlie the zones of thicker crust and are the presumed source for the iron enrichment. Copyright © 2011 by the American Geophysical Union.
News Article | May 18, 2016
Iron fertilization in the Pacific is not an effective solution to climate change, a new research has revealed. Experts believed that iron fertilization can cause sporadic growth of algae that absorbs carbon in the ocean. They said more iron means will result in higher algae productivity, thus, increasing the carbon dioxide absorbed from the atmosphere and sank to the sea floor. However, airborne dust irons in the Pacific did not translate to an increase in algae's ability to absorb carbon dioxide in the atmosphere, said Gisela Winckler, study lead author and a geochemist from Lamont-Doherty Earth Observatory (LDEO) in Columbia University. In fact, the study correlated that previous iron fertilization in the Pacific have resulted in lower production of algae. Even though iron fertilization conducted in the past have controversial outcomes, it does not suggest that the same findings will be applicable in other areas. Winckler is presently working with LDEO researcher and co-author Robert Anderson in studying iron dust fertilization and its effects on the Southern Ocean. In 2004, the European Iron Fertilization Experiment (EIFEX) in the Southern Ocean was successful in making algae captured carbon dioxide in their organic tissue. On the other hand, in 2009, German-Indian Lohafex experiment in the South Atlantic Ocean only resulted in minimal algal bloom, most of which were consumed by marine animals. This has resulted in carbon dioxide going into the food cycle, instead of sinking it. The Intergovernmental Panel on Climate Change (IPCC) included iron dusts in the climate change alleviation report (PDF), but also warned against its possible negative effects. The report stated that, while some areas may experience high productivity, downstream marine life may suffer due to low levels of nutrients. Other ill effects of iron dusts include deep ocean acidification, expansion of dead zones with minimal oxygen, but high nitrous oxide, which is more potent that carbon dioxide. The study also referenced the authors' earlier work, which tackled iron dust biological response in the Pacific about 20,000 years ago and expanded the study to include the algae growth from nearly half a million years ago. From there, they concluded that the productivity of the algae did not increase in the five glacial periods. Cores from deep sea sediments were gathered from three different areas in the equatorial Pacific. The researchers used these to test for barium to establish the level of organic matter that was brought to the ocean floor. The researchers also tested for opal that came from groups of algae. Thorium-232 measurements were also taken to identify the iron dust that came from land. The authors concluded that the purposeful addition of iron to the water surface of the Pacific will not result in a significant impact on mitigating the effects of atmospheric carbon dioxide. "While it is well recognized that atmospheric dust plays a significant role in the climate system by changing planetary albedo, the study by Winckler et al, convincingly shows that dust and its associated iron contents is not a key player in regulating the oceanic sequestration of CO2 in the equatorial Pacific on large spatial and temporal scales," said Stephanie Kienast, a marine geologist and paleoceanographer from Dalhousie University, and was not involved in the study. The study was published in the Proceedings of the National Academy of Sciences on May 16. © 2016 Tech Times, All rights reserved. Do not reproduce without permission.
News Article | February 3, 2016
Like most researchers at Columbia University’s Lamont–Doherty Earth Observatory (LDEO), Park Williams is expected to win research grants to cover his salary. But times are tough for climate scientists, who face flat levels of government funding in an ever-expanding pool of competitors. Two years into a post as an assistant research professor, the 34-year-old bioclimatologist had yet to receive a single grant. But on 22 January the Center for Climate and Life, a new research centre at Columbia that is seeking to raise funds from the business community, awarded Williams US$180,000 for his research on historical drought and fire cycles. Michael Puma, an environmental modeller at Columbia and NASA’s Goddard Institute for Space Studies, received $190,000 to investigate the impact of climate change on the global food system. “I was beginning to worry about my future here and wondering if I’d be wise to begin applying for more-traditional professorships,” says Williams. “Now I’ll have time to actually do research.” With climate-science funding under perennial threat in Washington DC, Columbia is engaging corporate philanthropists to boost research into the effects of projected environmental changes and how human systems can adapt. Seeded by Columbia with an initial budget of $3.1 million over five years, the Center for Climate and Life hopes to build a $200-million endowment that disburses around $10 million annually. “It’s a very new way of funding science,” says Peter de Menocal, a palaeoclimatologist at the LDEO in Palisades, New York, who is directing the centre. The centre will supplement salaries and research costs for scientists at Columbia, as well as at NASA’s Goddard Institute for Space Studies, which is located on the Columbia campus in New York City. De Menocal says that the centre will apply the same peer-review procedures used by the US National Science Foundation to ensure that its grants are directed towards the best research proposals. With roughly 85% of scientists at the LDEO reliant on government grants for their salaries, de Menocal says, two decades of stagnant budgets for the environmental sciences have taken a toll. And Republicans in the House of Representatives, many of whom deny the reality of global warming, have attempted repeatedly to cut funding for climate-related research. De Menocal says that the funding situation has many young Earth scientists rethinking their career choice because of what he calls “a silly ideological divide”. The new institute should give them needed job security, he says, and allow the community to identify and pursue new research paths without waiting for Washington to come around. Others have also recently turned to private philanthropy to fund climate research. “It is going to be very hard for the government to undertake a really big increase in federal research,” says Margaret Leinen, director of the Scripps Institution of Oceanography in La Jolla, California. In August, Scripps opened the Center for Climate Change Impacts and Adaptation with a donation of $5 million from energy executive Richard Hertzberg and his wife Carol Dean Hertzberg. And the Grantham Foundation for the Protection of the Environment, founded by investment manager Jeremy Grantham and his wife Hannelore, has helped to establish similar research institutes at multiple universities, including the Grantham Research Institute on Climate Change at the London School of Economics. One of the Columbia centre’s initial partners is the World Surf League (WSL) in Santa Monica, California, which is the governing body of professional surfing. The organization says it seeks to promote environmental awareness among more than 120 million surfing fans around the world. As part of that partnership, Columbia plans to develop an online certificate programme focused on ocean science and conservation. The courses will be open to anybody beginning in 2017 and may evolve into a formal master’s degree programme. “We’ve got this perfect combination of science and soul,” says Scott Hargrove, chief marketing officer for the WSL, which plans to announce its funding commitment as early as February. “Surfing has the power to move culture,” he says, with Columbia driving the science and education, and surfers serving as public ambassadors. De Menocal is also in talks with French aerospace giant Airbus, which would provide the fuselage for a research aircraft that could be readily equipped with instruments to study everything from the atmosphere to rainforests and polar ice sheets. De Menocal says that the center is currently working on a viability study for the project. “We want to change the way we do and fund science,” says de Menocal, “and fast track the science we need to understand how climate impacts people.”