Consequences of global change for oceans: A review

The possible effects of global climate change on the oceans are described through a review of the results produced by GCM's that explicitly incorporate the dynamics of the interior of world oceans. Changes at asymptotic equilibrium influence the whole water column, but equilibrium in the deep sea is reached after several thousands years. The transient response of these models after 25 years following the onset of the perturbation (doubling or quadrupling of atmospheric CO₂) affects the upper layer of the oceans (<1000 m) producing an increase in temperature between 2–4 °C. Models with realistic geography, as compared with simplified ones with N-S symmetry, produce warming near the north pole but a small cooling close to the antarctic continent. The main impacts of the predicted changes upon marine ecosystems are identified within several possible scenarios. Special mention is made of the expansion/contraction of pelagic habitats, oceanic island habitats, ocean wide distributional changes and the dynamical effects upon bioproduction.