and salt contrast between the North Pacific and Southern Ocean would have been the sudden onset of deep convection in the North Pacific. Bottom waters formed would have filled deep Pacific basins and flowed through the Indonesian passage into the eastern Indian Ocean basin, and the locus of deep-wat...
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.675.6550 http://www.nasa.gov/pdf/121648main_ais2.pdf |
| Summary: | and salt contrast between the North Pacific and Southern Ocean would have been the sudden onset of deep convection in the North Pacific. Bottom waters formed would have filled deep Pacific basins and flowed through the Indonesian passage into the eastern Indian Ocean basin, and the locus of deep-water formation along Antarctica would have shoaled (16). How would methane hydrate dissociation and an abrupt change in ocean circulation have affected climate? The injection of 2000 Gt of CH 4 into the oceans over È10,000 years (the amount necessary to drive the d13C excursion) would have been insufficient to raise atmo-spheric CO 2 concentrations enough to drive whole-ocean warming of 4 to 5-C. The radia-tive forcing associated with a 70- to 160-ppmv increase in CO 2 would have caused only È1-C warming (21), and therefore the clath-rate hypothesis necessitates still unresolved climatic feedbacks to amplify and sustain PETM warmth. The abrupt switch to convection in the North Pacific is modeled to have warmed the deep ocean by up to 3 to 5-C (Fig. 1) (16) and could have driven the PETM by main-taining high levels of atmospheric CO 2 and water vapor. Circulation-induced ocean warm-ing could have driven additional increases in atmospheric CO 2 by destabilizing methane hydrates in deep ocean sediments (16). The solubility of CO 2 in seawater would also have decreased because of temperature and salinity changes, promoting higher atmospheric CO 2 Tropical ocean warming would have also promoted a more vigorous hydrologic cycle, higher evaporation rates, and saturation vapor pressures, resulting in increased levels of atmospheric water vapor (22), consistent with proxy data for surface water salinity (7, 8) and humidity (23, 24) across the PETM. The added radiative absorption from water vapor would have heightened the sensitivity of surface temperatures to rising atmospheric CO |
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