Shaped by Water

For an equator straddling group of islands, the Galapagos is surprisingly un-tropical. Darwin noted that an ocean current might be the main reason for the weather there, and he was right! the key in understanding the archipelago is understanding ocean currents. An equatorial location stabilizes surface climate throughout the year, while being at an intersection of several currents, that vary in intensity & temperature, allows parts of the islands to have both tropical and temperate weather conditions.

Currents & climate

The sun’s energy reaches our home planet in the form of radiant light and heat. Because the Earth is spherical, the equator gets more direct solar energy than other places in the world, making equatorial areas hotter while areas closer to Earth’s poles colder. This heat variability between regions gets balanced by motions in the atmosphere & oceans, they move in the form of winds & currents. Hot air and water rise while cold air and water drop, causing the winds & currents to continuously move between different regions (“Atmospheric Circulation” & ”Ocean gyres”), making up a looping conveyor belt of varying heat around the earth. Our climate is a solar powered system.

Convergence of Currents

Isolated in the middle of the pacific, 1000km away from the nearest land-mass, the Galapagos islands are surrounded by the ocean. Giving currents a higher degree of influence over both the climate and biodiversity there, so much so that there’s reason to believe that currents kickstarted its transformation millions of years ago.

In a process called “Upwelling”, colder water flows upwards from the deepest parts of the ocean, the earliest parts of the food chain get pushed up, feeding ecosystems with the nutrition they need to thrive. We can imagine ocean currents as a bunch of people that travel, mainly by sailing (wind-power) while carrying heat and food to spread wherever they go, affecting the climate, ecosystem, and biodiversity.

So what are the different currents that converge in the Galapagos?

The “Peru”

Also known as the “Humboldt” current, it comes from Antarctica, and one of three major influencers in the Galapagos. There’s always some part of it passing through the islands year-round, but the biggest concentration is from June till October. Starting from the south pole —not where Santa lives*— and heading up the western side of South America, from Chile all the way to Peru, it picks up lots of nutrients to share along the way with the cold water they carry. It’s found mainly around the southern and central portions of the archipelago. The cold it moves around has the most influence over the climate in the Galapagos.

*Unlike Santa, currents actually give out presents (in the form of upwelled nutrient-rich water).

the “SEC”

The second major influencer is the South Equatorial Current, it flows along the equator. Once it gets to the Galapagos, it moves around the whole group of islands, concentrating more around the southern and central ones, spreading the warm water it carries.

Both “Peru” & “SEC” get to the islands around the same time, meeting at the equator before taking a turn west towards them. The varying heat they spread creates a cool and misty season known as garua, keeping the islands’ climate mild.

The “NECC“

The North Equatorial Counter Current is similar to the “SEC“ in characteristics, route, and timing but cruise in the opposite direction, crowding and squeezing between the two westward-flowing currents along the equator.

the “Panama”

“Panama” comes down from the northeast along Central America. Although not the most influential, it spreads warm & cozy water around the northern islands, when the “Peru” current weakens between December and May, it starts to rain in short but sharp showers by then.

the “Cromwell“

The final but possibly most important influencer, the “Cromwell“ current (or Pacific Equatorial Undercurrent) is like the philanthropists & change makers that have been playing a role in the community for a long time, there’s always some of them helping out. Starting from the western Pacific ocean, it heads eastward along the equator, nonstop until it reaches the Galapagos. They don’t sail like the others though, instead, they travel in fast submarines 100 meters below the surface of the ocean. Once they reach the western islands it emerges and spreads cold & rich water before continuing the journey through the central islands. The “Cromwell“ might’ve been responsible for changing the ecosystem & biodiversity of what was a bunch of barren volcanic islands into what they have become now. By bringing up cold nutrient-rich water to the surface, it feeds the living aquarium that is the Galapagos.