New NASA satellite measurements show that the strengthening 2026 El Niño is already reducing phytoplankton abundance across a broad part of the central equatorial Pacific, an early ecological change that could spread through the marine food web. NASA Earth Observatory reported on August 10 that June data from the PACE satellite revealed substantially lower surface chlorophyll than in June 2025, when Pacific conditions were neutral.
Chlorophyll is the light-capturing pigment found in most phytoplankton, the microscopic organisms that form the base of much of the ocean food chain. NASA compared monthly averages collected by PACE's Ocean Color Instrument, which measures blue and green light reflected from the sea. The strongest difference appeared near the equator north of New Zealand, where the 2026 map showed a much narrower band of productive green water.
NASA oceanographers Matthew Kehrli and Graham Trolley attributed the decline to a familiar El Niño mechanism. Weaker easterly trade winds allow the warm surface layer to deepen and curb the rise of cool, nutrient-rich water from below. With less nourishment reaching sunlit surface waters, phytoplankton growth falls. The researchers expect the low-chlorophyll region to become broader or more pronounced as El Niño develops.
NOAA's Climate Prediction Center said the coupled ocean-atmosphere system was already reflecting a strengthening El Niño. Its July assessment gave the event a 97 percent chance of continuing into early Northern Hemisphere spring 2027 and an 81 percent chance of becoming very strong during October through December. NOAA cautioned that even powerful events do not produce typical effects everywhere, but stronger episodes shift the odds toward larger seasonal disruptions.
The biological signal matters because phytoplankton feed zooplankton, which in turn support fish, seabirds and marine mammals. Past El Niño events have sharply reduced Peru's anchovy catches. Peru's Ministry of Production suspended fishing for anchovy and white anchovy in the north-central zone in June, citing scientific assessments of intensified warm conditions and vulnerability of the stock, while leaving any reopening dependent on updated evidence.
PACE, launched in February 2024, will now observe its first complete El Niño with near-daily global measurements across more wavelengths than earlier ocean-color missions. NASA researchers plan to use those data to distinguish how specific phytoplankton communities respond and to track related changes in land vegetation, clouds and aerosols. The observations should clarify how rapidly a climate cycle can reorganize ocean productivity and where ecological pressure is likely to intensify next.
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