Isro satellite detects sharp drop in marine productivity as El Niño warms Pacific

An Isro satellite has detected a decrease in surface chlorophyll-a levels in the Pacific Ocean during June 2026, indicating changes in marine productivity and early signs of the El Nino climate phenomenon. The Oceansat-3 satellite, launched in 2022, tracks physical changes in the ocean and variations in marine biology. Scientists at Isro's National Remote Sensing Centre in Hyderabad analyzed satellite data from the Pacific Ocean between April and June across 2023, 2024, 2025, and 2026.

While April to June 2024 and 2025 showed neutral El Nino-Southern Oscillation (ENSO) conditions, June 2026 revealed a noticeable decline in surface chlorophyll-a levels as El Nino began developing. This decline in chlorophyll-a, which is present in phytoplankton forming the base of the ocean food chain, suggests reduced marine productivity.

During El Nino events, weaker trade winds along the equatorial Pacific disrupt ocean circulation and hinder the upwelling of nutrient-rich, cold water from deeper layers. This results in slower phytoplankton growth and smaller regions where it can thrive, leading to lower chlorophyll-a concentrations near the ocean surface. The early satellite observations emphasize how minor changes in ocean biology can reveal broader climate shifts.

With El Nino potentially intensifying in the months ahead, satellite monitoring becomes crucial in understanding these changes before their wider impacts are felt.