NASA satellite imagery has captured a striking transformation linked to Super El Niño: parts of the equatorial Pacific have shifted from a rich green to a vivid blue over the past year.
The colour change is tied to El Niño’s disruption of ocean currents. Normally, those currents lift cold, nutrient-packed water toward the surface, supporting photosynthesising plankton that can give the sea a brilliant emerald appearance.
When the nutrient supply is reduced, plankton populations fall. As a result, the Pacific’s surface waters lose their green tint and are replaced by broader stretches of deep, seemingly lifeless blue.
A comparison with NASA satellite observations from 2025 shows that the region retained its familiar green colouring for much of that year.
The latest observations, extending through this month, tell a different story, with waters along the equator now appearing noticeably bluer.
El Niño is one phase of the naturally recurring climate pattern known as the El Niño-Southern Oscillation.
The cycle typically shifts every two to seven years between the warmer conditions of El Niño and the cooler phase known as La Niña.
During El Niño, unusually warm water builds across the equatorial Pacific near South America. The resulting rise in ocean temperatures can influence weather systems around the world.
NASA satellite observations indicate that Super El Niño is making the Pacific appear bluer this year (top) than in 2025, as warmer water interrupts the nutrient supply that normally supports green phytoplankton.
Researchers believe the planet may be entering the early stages of an exceptionally powerful El Niño event, raising concerns about potentially severe impacts in the months ahead and through 2027.
In October, the National Oceanic and Atmospheric Administration estimated an 83 per cent probability that the event could become the strongest El Niño recorded since monitoring began in 1950.
NASA data shows that sea surface temperatures in the eastern Pacific are already 1.7°C (3°F) above the long-term average, with the possibility of a further increase in the months ahead.
The warm-water zone expanded during the spring and now spans millions of square miles, stretching from South America’s coastline into the central Pacific.
It is also the first El Niño event observed since NASA launched the PACE, or Plankton, Aerosol, Cloud, Ocean Ecosystem, satellite in 2024, giving scientists an unusually detailed view of the changing ocean.
PACE’s Ocean Colour instrument analyses the sea using hyperspectral imaging, recording wavelengths across visible, ultraviolet and infrared parts of the spectrum.
Dr Matthew Kehrli, a lead research scientist at NASA’s Goddard Space Flight Center, said: “Some people think of water as being just blue, but it’s amazing the multitude of colours the ocean can be.”
NASA measurements show that eastern Pacific sea surface temperatures are currently 1.7°C (3°F) above the long-term average.
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Data collected on October 14 shows the heat extending along Chile’s coastline and into the southeastern Pacific, with the boxed section tracing the movement of the warm water.
El Niño weakens the trade winds that normally push warm surface water west toward Australia. In some cases, those winds can even reverse direction.
That shift suppresses the rise of nutrient-rich deep water, reducing algae and plankton levels and contributing to the bluer ocean conditions recorded by NASA’s PACE satellite.
That decline can also trigger cascading effects across the entire marine ecosystem, forcing other animals to relocate to new feeding grounds in search of phytoplankton.
‘You have expectations of what you would think would happen, but to visually see the results with the data products that you’re working with in real time is gratifying,’ says Dr Kehrli.
Thanks to satellite observations, scientists actually got their first hint that a major El Niño year was coming all the way back in January.
Satellites built to measure sea levels picked up something called a Kelvin Wave building near Micronesia, in the western Pacific Ocean.
Kelvin Waves are slow-moving pulses of water spanning thousands of miles that act like underwater motorways transporting heat from west to east across the Pacific.
El Niño is even affecting sea levels in the Pacific, with some areas rising up to 1.3 feet (40cm) above average (shown in red)
That heat warms the air above them, causing it to rise and creating a change in air pressure that weakens the trade winds – kickstarting the El Niño chain reaction.
Dr Josh Willis, project scientist for sea level missions at NASA’s Jet Propulsion Laboratory in Southern California, says: ‘Kelvin waves are like the heartbeat of El Niño.
‘And our sea level satellites let us peer into the ocean and watch every beat.’
By early April, NASA’s satellites saw that the Kelvin wave had reached the eastern Pacific and was already starting to warm sea surface temperatures.
Since warm waters also expand and rise, that change can be seen in a massive increase in sea levels within El Niño’s critical region.
Sea levels rose by as much as 1.3 feet (40cm) near South America and the coast of California, while sea levels dropped by up to eight inches (20cm) near Indonesia and Australia.
Dr Willis says: ‘El Niño touches almost all of us in some way every time it occurs. While many have seen what it can do, we look to the ocean to understand why.’
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