8 research outputs found
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North Atlantic Paleoceanography: The Last Five Million Years
In the North Atlantic, cold, relatively salty water sinks in the icy Labrador and Greenland seas, forming North Atlantic Deep Water (NADW). This circulates through the global ocean, driving ocean overturning and global heat transport and, thus, impacting global climate. As one of the most climatically sensitive regions on Earth, the North Atlantic has experienced abrupt changes to its ocean-atmosphere-cryosphere system, triggered by fluctuations in meltwater delivery to source areas of NADW formation. For about the past 100 thousand years, these abrupt jumps in climate state have manifested as ‘Dansgaard/Oeschger’ (D/O) oscillations (millennial-scale warm-cold oscillations) and ‘Heinrich’ events in ice and marine sediment cores, respectively [e.g., Dansgaard et al.,1993; Bond and Lotti, 1995]. These Heinrich events are characterized as huge input of ice-rafted debris (IRD) and meltwater pulses, documenting episodes of sudden instability and collapse of the current Greenland ice sheets and the Laurentide ice sheet, the latter of which covered northern North America several times during the Pleistocene Epoch
Keeping Safe
[10] p. : col. ill. Secrets of nature. Cover title. A Joshua Morris book --P. [4] of cover. Illustrations, some with pull tabs, and simple text present some of the many ways that animals protect themselves from danger. Stanley F. Moss Pop-Up Book Collection, Gift of Eugene B. Navias.https://digitalcommons.risd.edu/specialcollections_books_popupandmovablebooks/1065/thumbnail.jp
Proceedings of the Integrated Ocean Drilling Program Volume 303/306
Climate change and earth-ocean atmosphere systems
Evidence based effectiveness of vaccination against Mannheimia haemolytica, Pasteurella multocida and Histophilus somni in feedlot cattle for mitigating the incidence and effect of bovine respiratory disease complex
A Cenozoic record of the equatorial Pacific carbonate compensation depth
Atmospheric carbon dioxide concentrations and climate are regulated on geological timescales by the balance between carbon input from volcanic and metamorphic outgassing and its removal by weathering feedbacks; these feedbacks involve the erosion of silicate rocks and organic-carbon-bearing rocks. The integrated effect of these processes is reflected in the calcium carbonate compensation depth, which is the oceanic depth at which calcium carbonate is dissolved. Here we present a carbonate accumulation record that covers the past 53 million years from a depth transect in the equatorial Pacific Ocean. The carbonate compensation depth tracks long-term ocean cooling, deepening from 3.0-3.5-kilometres during the early Cenozoic (approximately 55-million years ago) to 4.6 kilometres at present, consistent with an overall Cenozoic increase in weathering. We find large superimposed fluctuations in carbonate compensation depth during the middle and late Eocene. Using Earth system models, we identify changes in weathering and the mode of organic-carbon delivery as two key processes to explain these large-scale Eocene fluctuations of the carbonate compensation depth. © 2012 Macmillan Publishers Limited. All rights reserved