Hydrosphere Contents

4. Oceans

All of the water which sinks at one place in the ocean is upwelled eventually somewhere else

Satellite data showing chlorophyll-rich algae.

The upwelling of cold ocean bottom water often takes place thousands of miles and many hundreds of years after the water has sunk away from the surface. Some of the world's most important upwelling areas are off the coasts of Southern Africa and Peru. Upwelling creates chlorophyll-rich (algae) belts extending up to 1,000 km away from the coastline. The red area shows the greatest abundance. These are very productive regions and support a very rich ecosystem.

What happens to cold water that sinks to the bottom of the oceans?