The arrival of El Niño Costero, currently under alert according to the Multisectoral Commission for the National Study of the El Niño Phenomenon (Enfen), was discussed by experts at a recent seminar held at Pontificia Universidad Católica del Perú (PUCP), according to a March 16 statement.
The topic is important because El Niño Costero brings intense rains, floods, and landslides that severely affect various regions in Peru. Understanding its origins and effects can help improve prevention and response strategies.
During the seminar “Climate Extremes: Marine Heatwaves, Atmospheric Waves, and Storms,” Dr. Laura Paccini from PUCP’s Geography and Environment section and Dr. Adolfo Chamorro from PUCP’s Mathematics section explained that El Niño Costero does not have a single cause. They said it results from several factors including special conditions in the sea, atmosphere, soil, as well as how cities and prevention systems are prepared to respond. Both emphasized that “this is not understood only from the climate perspective but also from prevention and infrastructure.” The event brought together national and international researchers to analyze physical processes and recent advances in studying extremes in the coupled ocean-atmosphere system.
Chamorro highlighted that marine heatwaves off Peru occur when sea temperatures remain unusually high for several days. He said these events alter marine ecosystems and help explain extreme weather affecting the country. “Part of the challenge is understanding that these circumstances do not necessarily start where we see their impact but in processes activated earlier, such as changes in the ocean,” Chamorro said. He recalled that during the 2017 El Niño Costero there was an unusual marine heatwave lasting several months. For 2026, he warned there could be up to a 20% increase in weak winds along northern coastal areas, which could favor such events.
Paccini focused on how soil moisture heterogeneity increases large convective systems responsible for much of annual rainfall in tropical regions. She found that greater differences in soil moisture can increase large convective systems by about 40%. “The soil is not a passive element in these events; its conditions also influence how a storm organizes and grows,” Paccini said.
According to Enfen’s March 13 bulletin, an “El Niño Costero alert” remains active through December with weak magnitude expected for now but moderate strength possible by autumn. In addition to natural factors, insufficient drainage systems, vulnerable infrastructure, and weak response mechanisms multiply impacts when extreme weather occurs.
Recent figures published by Peru’s National Institute of Civil Defense (Indeci) reported 51 deaths during heavy rains between January and March 2026. Thousands were left homeless or living in damaged homes; regions like Arequipa saw over 4,000 people affected with four deaths reported alongside damage to homes, bridges, and roads.
Experts say addressing these challenges requires early warning systems, functional drainage networks, cleaning riverbeds and ravines, sustained investment in infrastructure, effective response capacity—and better translation of scientific knowledge into public decisions. As Chamorro and Paccini concluded: there is no single explanation or solution for El Niño Costero; instead Peru must learn to coexist with climate extremes without each episode becoming a major emergency.
