Pacific Ocean turns blue due to declining phytoplankton during El Niño

Satellite imagery from NASA shows the equatorial Pacific Ocean is transitioning from its typical greenish hue to a bright blue color. This visual shift is linked to a significant reduction in phytoplankton, the microscopic organisms that form the base of the marine food web.

Experts attribute this change to the 2026 El Niño phenomenon. The warming of surface waters and the weakening of trade winds have disrupted upwelling processes, which normally bring nutrient-rich cold water from the deep ocean to the surface. Without these essential nutrients, phytoplankton populations are declining.

Scientists warn that this biological shift could have severe consequences for marine ecosystems, potentially impacting the entire food chain—including fish, birds, and marine mammals—and reducing the ocean's capacity to absorb atmospheric carbon dioxide.