Wind, Ekman transport, deep water, nutrients, phytoplankton, coastal productivity, fisheries, cold water, oxygen, ocean currents, downwelling, eastern boundary currents, climate patterns, marine heatwaves, kelp forests, and food webs
Upwelling
Upwelling is the rise of deeper, colder, often nutrient-rich water toward the ocean surface, where it can fuel plankton growth and productive marine food webs.
What upwelling is
Upwelling is ocean water moving upward. Most people notice its effects rather than the motion itself: colder water near a beach, foggier coastal weather, plankton blooms, or rich fishing grounds where deep nutrients reach sunlight.
How wind starts it
Along many coasts, persistent winds push surface water away from shore. Water from below rises to replace it. Because Earth rotates, the surface water does not move exactly with the wind; this deflection is part of a process called Ekman transport.
Nutrients and plankton
Deep water often carries nitrate, phosphate, and other nutrients released as sinking organic matter decomposes. When that water reaches the bright surface layer, phytoplankton can grow quickly, creating food for zooplankton, fish, and larger animals.
Coastal hotspots
Some of the best-known upwelling systems sit along eastern ocean boundaries, such as the California, Humboldt, Canary, and Benguela current systems. These regions are relatively small in area but can be extremely important for global fisheries.
Upwelling is not always good news
The same deep water that brings nutrients can also be cold, low in oxygen, or naturally higher in dissolved carbon dioxide. In coastal areas already stressed by warming, acidification, or pollution, strong upwelling can create difficult conditions for shellfish, fish, and kelp.
Seasons and cycles
Upwelling often has a seasonal rhythm because wind patterns shift through the year. It can also strengthen, weaken, or move with climate patterns, storms, marine heatwaves, and changes in large-scale ocean circulation.
How scientists track it
Researchers use wind data, sea surface temperature, ocean color, buoys, ships, gliders, and models. Cold surface water and high chlorophyll can be clues, but scientists check multiple signals because not every cold patch or plankton bloom has the same cause.
Why it matters
Upwelling is one of the ocean processes that turns physics into food. It links winds, currents, chemistry, plankton, fisheries, kelp forests, seabirds, and coastal economies, which is why changes in upwelling can ripple far beyond the water column.