Currents Are King
The islands are not special just because of how they formed. They are teeming with life in part because of where they formed. The Galápagos Islands sit at the intersection of several major ocean currents—some warm, some cold.
The climate is dependent almost entirely on these currents, whichever one is prevalent at the time. And the currents, in turn, are influenced by the winds that push them.
Let’s start with the Humboldt current. This massive ocean current sweeps north from Antarctica up the western edge of South America. It carries cold, nutrient‑rich water along the coasts of Chile and Peru. It hangs a left when it reaches the Galápagos.
The Humboldt is a deep‑water current. Together with powerful trade winds it creates an effect called upwelling. The winds blowing across the ocean’s surface push water away. Water rises up from beneath the surface to replace the water that was pushed.
Upwelling helps create a rich marine ecosystem. As ocean organisms die, they sink to the bottom and decompose. The deep sea becomes filled with nutrients. Upwelling brings the deep, cold water to the surface. The nutrients provide food for microscopic organisms called phytoplankton. Phytoplankton are a key part of the ocean food chain. Marine animals feast on them.
Cromwell current
Peru Oceanic current
South Equatorial current
Humboldt current
PACIFIC OCEAN
GALÁPAGOS
ISLANDS
ECUADOR
South America
Panama current
Cold water with more nutrients rises up to replace water that is pushed away.
Surface winds push water away from the land.
phytoplankton
UPWELLING
Strong winds mix with deep currents to create upwelling. The ocean becomes plentiful with food.
When Currents Collide
From May through December, the Humboldt current collides with the warm‑water Panama current. The Panama current flows southward from Central America. When these two, dominant currents meet, they create a cool mist known as la garúa. Clouds condense over the islands and fall as mist in the highlands. From the ocean, the islands seem to disappear!
Meanwhile, the Cromwell current approaches from the west. It travels almost 13,000 kilometers (8,000 miles) across the Pacific Ocean from Hawaii. The current slams into the islands, upwells, then swirls around them. Like the Humboldt, the Cromwell is a deep‑water, cold current. It carries nutrients to the surface to fuel the marine food chain.
cactus finch
mistand fog around Isabela Island
Virtually all of the Galápagos penguins and fur seals live along the western shores of Isabela and Fernandina, where the upwelling is strongest. The water is cooler here, too.
At the same time, the South Equatorial current flows east to west through the Galápagos, also pushed by trade winds. This warm‑water current is the major surface current in the tropical Pacific.
Around December, the southeast trade winds slow down. They can no longer drive the Humboldt current toward the Galápagos. The warm Panama current becomes dominant through May. In some years, this brings high humidity and heavy tropical rains that can usher in the El Niño current.
The waters and currents moving around Galápagos Islands support life.
Disruptive Force
Wait. El Niño current? There’s another ocean current? Not really. The El Niño current only forms under certain conditions every few years. This current affects weather patterns by bringing more rain and potential flooding. It can last for months at a time.
El Niño can benefit plant life on the islands by bringing rain. This, in turn, leads to population booms for animals that eat plants.
During a harsh El Niño, the Humboldt current is cut off and the upwelling that normally takes place can’t happen. That means there isn’t enough food for sea animals. Sea lions, penguins, and marine iguanas die in great numbers. Many seabirds fail to rear young. It can take years for some populations to come back. At the same time, the abundant rainfall can make the normally dry lowlands green and lush. Land animals and small birds like finches then flourish.
It is a reminder to us that the Galápagos are a place where nature is fighting to stay in balance at all times. It is a place that was born of fire. It is fueled by wind and water. It is full of life.