NASA: El Niño's 2-to-7-Year Cycle Turns Pacific Ocean Blue

Satellite images released by NASA show the water color across the equatorial band of the Pacific Ocean shifting from green to a near-uniform cerulean blue over the past year, a change scientists attribute to this year's Super El Niño, according to the New York Post.

What do the satellite images actually show?

A side-by-side comparison cited by the Post shows the equatorial Pacific "awash in green" in 2025 data, with the most recent imagery showing the same stretch of ocean turned blue. The images come from NASA's PACE satellite team, which tracks ocean color as an indicator of biological activity below the surface.

Why does El Niño change the ocean's color?

The color shift traces back to phytoplankton, the microscopic organisms that anchor the marine food web and tint seawater teal, brown, or green depending on their concentration. Phytoplankton need cool, nutrient-dense water to thrive, and that water normally reaches the surface through upwelling currents.

El Niño disrupts that process. The weather pattern develops when weakened trade winds let unusually warm water build up across the central and eastern tropical Pacific, suppressing the upwelling that would otherwise deliver nutrients to the surface. Starved of those nutrients, phytoplankton populations drop sharply — and with them, the water's color.

"Some people think of water as being just blue, but it's amazing the multitude of colors the ocean can be," said Matthew Kehrli, a lead research scientist for the PACE satellite team at NASA's Goddard Space Flight Center, per the Post.

What is the El Niño–Southern Oscillation, and how often does it happen?

El Niño is one phase of a recurring climate pattern known as the El Niño–Southern Oscillation, or ENSO, which alternates roughly every two to seven years between a warmer El Niño period and a cooler La Niña phase. During an El Niño event, unusually warm water accumulates across the equatorial Pacific off South America's coast, a buildup that raises global temperatures and disrupts weather patterns worldwide, the Post reported.

What does the color shift signal for marine life?

Because phytoplankton sit at the base of the ocean food web, a sharp decline in their numbers ripples upward through fish, seabirds, and the larger species that depend on them. The Post's report frames the current event as a "Super El Niño," tied separately to record-breaking ocean temperatures that scientists warn threaten marine life broadly. The outlet also noted this year's El Niño has drawn attention for developing what researchers described as a "mutant" second arm, part of a broader pattern of unusual behavior scientists are tracking in the current cycle.

How is this El Niño showing up on land?

The same warming pattern driving the color change has produced visible effects on the coast. The Post's report includes an image of a man confronting what it calls historic El Niño tidal swells in Oceanside, California, on Oct. 11, 2026, illustrating how shifts far out in the equatorial Pacific can translate into coastal conditions thousands of miles away.

NASA has not published a timeline for when upwelling — and the green water phytoplankton produce — might return, and the Post's report does not specify one.