ISRO Satellite Detects Clearest Sign Yet Of "Mother Of All" El Nino Events

From a perch 741 kilometres above Earth, an Indian satellite is tracking what may be the best visible fingerprints of a strengthening El Nino. Long before shifts in rainfall become apparent and before the full impact on the Indian monsoon is felt, ISRO's EOS-06 satellite, better known as Oceansat-3 satellite, is detecting biological and atmospheric changes unfolding across the equatorial Pacific Ocean. These observations suggest that the world's climate system is moving towards a powerful El Nino event that scientists fear could intensify in the months ahead. Some say the Godzilla El Nino is emerging and its true and worst impact is still to be felt.

According to ISRO the observations from EOS-06/Oceansat-3 also complement the World Meteorological Organization (WMO) outlook. In its June 2026 El Nino/La Nina update, the WMO estimated an approximately 80% probability of El Nino conditions developing during June–August 2026, with several forecast models indicating the possibility of a strong event. By late July, the WMO reported that El Nino conditions were intensifying and were expected to strengthen during August–October 2026. Satellite observations from EOS-06/Oceansat-3 reveal a clear decline in marine productivity associated with the developing El Nino conditions across the equatorial Pacific Ocean.

The key signal being watched by scientists is a sharp decline in chlorophyll-a, a pigment found in microscopic marine plants known as phytoplankton. These tiny organisms form the foundation of the ocean food chain. According to analysis by ISRO's National Remote Sensing Centre in Hyderabad, of June 2026 observations revealed a notable reduction in surface chlorophyll-a across parts of the tropical Pacific compared with the same period in 2024 and 2025 when El Nino Southern Oscillation or ENSO conditions were largely neutral. At the same time, EOS-06 detected a reversal of ocean surface winds from easterlies to westerlies, a classic sign associated with the development of El Nino conditions. ISRO released the data and images today.

What makes this observation particularly important is that chlorophyll responds almost immediately to changes in ocean dynamics. Scientists say chlorophyll depletion may provide an earlier indication of El Nino development than traditional sea surface temperature based indices that often require sustained warming over several weeks before an event is formally declared.

According to Dr Prakash Chauhan Director of ISRO's NRSC, warming waters in the eastern Pacific suppress the upward movement of colder nutrient rich waters from deeper layers of the ocean. As this process weakens, phytoplankton growth declines and the change is captured by the Ocean Colour Monitor on board the Indian EOS-06 satellite operated by ISRO. The same satellite also carries a Scatterometer that detects the wind reversals associated with El Nino. Together, the two instruments provide a powerful early warning system for monitoring the onset and evolution of the climate phenomenon.

"The important inference is that apart from Sea Surface Temperature (SST), phytoplankton depletion also gives clear indication of El Nino status and its impact on ocean response in the Pacific Ocean," Prakash Chauhan said.
ISRO scientists note that if El Nino intensifies further as forecast, the low chlorophyll region across the Pacific could become even more pronounced in the coming months.

El Nino is the warm phase of the El Nino Southern Oscillation or ENSO, one of the most influential climate systems on Earth. During normal years, trade winds push warm surface waters westward across the Pacific, allowing cooler nutrient rich waters to rise near South America. During El Nino, these winds weaken or even reverse. Warm water spreads eastward, ocean upwelling collapses and marine productivity declines. The resulting changes alter atmospheric circulation patterns across the globe, affecting rainfall, drought, floods and temperatures on multiple continents.

For India, El Nino is particularly significant because it has historically been associated with weaker southwest monsoon rainfall. Not every El Nino leads to drought in India, but strong events have often coincided with deficient rainfall, reduced soil moisture, pressure on agriculture and concerns over water resources. Variability in Pacific Ocean winds associated with El Nino can influence the large scale circulation that drives monsoon rainfall over the Indian subcontinent.

The India Meteorological Department says moderate El Nino conditions currently prevail over the equatorial Pacific Ocean, with sea surface temperature anomalies remaining above normal across the central and eastern Pacific. According to the IMD, these conditions are expected to strengthen further through the remainder of the southwest monsoon season. Forecasts from the Monsoon Mission Coupled Forecast System also indicate continued strengthening of El Nino conditions during the season.

The strengthening signal is not being tracked only by India. The World Meteorological Organization has also warned that a very strong El Nino is emerging and could persist into early 2027, raising concerns about extreme weather, higher global temperatures and widespread climate disruptions. The prospect of a powerful El Nino developing at a time when global temperatures remain exceptionally high has drawn close attention from climate scientists around the world.

What makes EOS-06 especially valuable is its ability to observe both biological and physical indicators of climate change from space. Launched aboard the Polar Satellite Launch Vehicle (PSLV) on 22 November 2022, the satellite carries the Ocean Colour Monitor-3 and Scatterometer to track marine ecosystems, ocean winds and atmosphere ocean interactions. By combining measurements of chlorophyll and wind patterns, scientists can monitor the ocean's response to El Nino almost in real time.

Scientists caution that while chlorophyll decline and wind reversals are strong indicators, the evolution of El Nino will continue to be monitored alongside sea surface temperature, thermocline depth, and sea level height and ocean circulation patterns. Even so, EOS-06 has already demonstrated an important capability. From hundreds of kilometres above Earth, the satellite is detecting subtle changes in marine life and ocean winds that could herald the arrival of one of the most consequential climate events on the planet.

If forecasts prove correct, the message emerging from the Pacific is clear. The developing El Nino is already leaving its fingerprints on the oceans and an Indian satellite is among the first witnesses. From its 741 kilometre vantage point, EOS-06 may be offering scientists an early glimpse of what could become one of the strongest El Nino events in recent years, potentially carrying major implications for global weather and the Indian monsoon alike.