Namibia Upwelling: Ocean Meadows off tthe Desert

Abstract

A central finding of the ocean drilling expedition off Namibia and South Africa (Leg 175, 1997) is that the history of the intense coastal upwelling in that region is intimately tied into global climate change and the geochemistry of the deep ocean. The high productivity associated with this flow of cool, nutrient-dense deep water upwards along the coast cannot simply be described as a progressive increase of productivity that began ten million years ago. Instead, physical upwelling of cold water follows global cooling rather closely, while silicate content of the water (crucial for diatom production) runs out of phase with upwelling but is highly correlated with changes in thermohaline circulation.