Observing an ocean rise from space has a subtle unnerving quality. Not dramatically, not all at once, but inch by inch, measured in centimeters by a 1,336-kilometer-high satellite the size of a small bus. That is precisely what the Sentinel-6 Michael Freilich satellite has been doing, and the images it took over the Pacific Ocean in early June 2026 are being compared to one of the most catastrophic weather events in recorded history.
After sea surface temperatures in the central and eastern equatorial Pacific rose at least 0.5 degrees Celsius above average for several months in a row, NOAA officially declared the return of El Niño on June 11. However, height—rather than temperature—is the figure that is truly drawing attention. The sea surface rises as a result of the physical expansion of warming ocean water. NASA scientists have been monitoring that increase in sea surface height, and the maps produced by NASA’s Jet Propulsion Laboratory don’t offer much comfort.
Large areas of deep red, which indicate sea levels much higher than average, are seen spreading throughout the central and eastern Pacific in the satellite imagery from June 8. It’s difficult not to notice a change as you stand at JPL and gaze at those maps. This data is not abstract. It depicts the massive heat that is building up inside the ocean, heat that will eventually affect entire continents’ crop cycles, weather patterns, and coastlines.
Severine Fournier, deputy project scientist for Sentinel-6 Michael Freilich, is drawing a comparison that makes this event worth paying closer attention than usual. She pointed out that on June 8, conditions in the western Pacific were very similar to those on the same day in 1997, when one of the strongest El Niño events ever recorded occurred. Although the eastern Pacific still lags behind that standard, the difference seems to be closing. From the west, more Kelvin waves—those enormous, miles-wide swells of warm subsurface water—are already on their way.
Since Kelvin waves seem abstract until you grasp the mechanics, it’s worth taking a moment to consider what they really are. Warm water that had been building up near Indonesia and Australia starts to move east when trade winds in the western equatorial Pacific weaken and momentarily reverse direction. The upwelling that typically keeps Pacific coastal waters colder is effectively smothered by this warm water, which also lowers the thermocline and deepens the upper ocean layer. The current NASA Pacific sea level rise is the surface manifestation of that buried heat, a subsurface reservoir that climate scientists consider to be a far more accurate predictor of El Niño’s ultimate intensity than surface temperature alone.
Here, Fournier’s own words have some significance. “For now, it looks like it’s going to be a big one — more so than I would have said last week — but we still need more observations to know what’s going to happen.” Scientists say things like that cautious hedge at the end when they observe something moving more quickly than their models predicted.
Wide areas of the tropical Pacific experienced ocean temperature anomalies that were more than three degrees above average during the most recent Super El Niño, which occurred in 2015. It caused severe drought in some parts of Africa, upset rainfall patterns from Indonesia to Peru, and dumped record amounts of precipitation on the U.S. West. Similar risks would persist into late 2026 and early 2027 if a similar event occurred in 2026. This is the exact window that long-range forecasts are currently raising concerns about.
The scientific community seems to be in that awkward place where data is beginning to surpass public discourse. The satellite readings are unambiguous. The Kelvin waves can be quantified. There are historical parallels. Ocean activity over the next few weeks will determine whether this event ultimately rivals 1997 or settles into something more modest. However, it appears that the Pacific has already decided on its course.
