Author:
A. Gnanadesikan (1), J. L. Russell (2), and Fanrong Zeng (3)

1) NOAA Geophysical Fluid Dynamics Laboratory, Princeton, NJ, USA
2) Department of Geosciences, University of Arizona, Tucson, AZ, USA
3) RSIS, Princeton, NJ, USA

Abstract:
Since the upper ocean takes up much of the heat added to the earth system by anthropogenic global warming, one would expect that global warming would lead to an increase in stratification and a decrease in the ventilation of the ocean interior. However, multiple simulations in global coupled climate models using an ideal age tracer which is set to zero in the mixed layer and ages at 1 yr/yr outside this layer show that the intermediate depths in the low latitudes, Northwest Atlantic, and parts of the Arctic Ocean become younger under global warming. This paper reconciles these apparently ontradictory trends, showing that the decreases result from changes in the relative contributions of old deep waters and younger surface waters. Implications for the tropical oxygen minimum zones, which play a critical role in global biogeochemical cycling are considered in detail.

Published by :

Copernicus GmbH on behalf of the European Geosciences Union.

Ocean Science., 3, 43-53, 2007
© Author(s) 2007. This work is licensed under a Creative Commons License.

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Technorati : Northwest Atlantic, Oxygen, anthropogenic, artic ocean, biogeochemical, climate model, cycling, deep water, global warming, mixed layer, ocean, surface waer