1997–1998 El Niño

1997–1998 El Niño
Name	1997–1998 El Niño
Type	Climate anomaly
Start	1997
End	1998
Affected	Global
Notable	Strongest 20th-century ENSO event

1997–1998 El Niño was one of the strongest El Niño–Southern Oscillation events of the 20th century, producing widespread climatic disruptions, extreme weather, and large economic losses across multiple continents. It altered sea surface temperatures, atmospheric circulation, and precipitation patterns, influencing phenomena observed in the Pacific, Atlantic, Indian, and Southern Oceans. The event mobilized scientific institutions, national governments, international agencies, and humanitarian organizations to monitor, forecast, and respond to cascading impacts on agriculture, fisheries, infrastructure, and human livelihoods.

Background and Causes

The event arose from coupled ocean–atmosphere interactions described in studies by researchers at National Oceanic and Atmospheric Administration, Scripps Institution of Oceanography, Commonwealth Scientific and Industrial Research Organisation, Japan Meteorological Agency, and British Antarctic Survey. Preconditioning factors included anomalous tropical sea surface warming noted by crews aboard ships referenced in records from NOAA Fisheries Service and research cruises supported by Woods Hole Oceanographic Institution and Lamont–Doherty Earth Observatory. Walker circulation shifts recorded by stations tied to Global Atmosphere Watch and data assimilated into models at European Centre for Medium-Range Weather Forecasts and NASA Goddard Institute for Space Studies preceded deep atmospheric convection changes tracked by Tropical Rainfall Measuring Mission and Geostationary Operational Environmental Satellite instruments. Interactions with the Madden–Julian Oscillation and the Pacific Decadal Oscillation modulated the onset alongside feedbacks studied by teams at University of California, San Diego, Princeton University, Massachusetts Institute of Technology, and University of Tokyo.

Development and Peak Events

Warming across the central and eastern equatorial Pacific peaked following Kelvin wave propagation observed by TOGA and TAO/TRITON buoy arrays maintained by NOAA Pacific Marine Environmental Laboratory and Japan Agency for Marine-Earth Science and Technology. Satellite altimetry from Jason-1 precursor missions and sea surface temperature fields from Advanced Very High Resolution Radiometer documented the eastward shift of convection affecting coastal regions of Ecuador, Peru, and Chile. Atmospheric teleconnections altered the jet streams monitored by National Weather Service, Met Office (United Kingdom), Météo-France, and Bureau of Meteorology (Australia), producing record warmth and precipitation extremes validated by World Meteorological Organization datasets and analyses from Intergovernmental Panel on Climate Change contributors. Storm tracks modified by the anomaly increased cyclone activity reported by Joint Typhoon Warning Center and National Hurricane Center while influencing monsoon variability studied by Indian Meteorological Department and Indonesia Meteorology, Climatology, and Geophysics Agency.

Global Climatic and Environmental Impacts

The event correlated with global temperature excursions included in compilations by National Aeronautics and Space Administration and Hadley Centre. Coral bleaching episodes affected reefs monitored by Australian Institute of Marine Science, Center for Tropical Marine Ecology, Smithsonian Institution, and non-governmental groups like Conservation International, impacting biodiversity in regions including the Great Barrier Reef, Galápagos Islands, and Coral Triangle. Oceanic fisheries faced declines reported by Food and Agriculture Organization and International Union for Conservation of Nature assessments, with effects on stocks exploited by fleets from Peru, Ecuador, Japan, China, and United States. Glacial melt accelerations noted by United States Geological Survey and Instituto Geofísico del Perú altered runoff into basins studied by International Centre for Integrated Mountain Development and World Bank-funded hydrological projects. Wildfire outbreaks intensified in areas with drought signals referenced by Canadian Forest Service, United States Forest Service, and Instituto Nacional de Pesquisas Espaciais.

Regional Socioeconomic and Humanitarian Effects

Agricultural shortfalls and flood damages prompted humanitarian responses coordinated by United Nations Office for the Coordination of Humanitarian Affairs, World Food Programme, United Nations Children's Fund, and regional agencies like African Union and ASEAN. Economic losses featured in analyses by International Monetary Fund, Organisation for Economic Co-operation and Development, and Inter-American Development Bank, with sectors such as coffee, sugarcane, and rice affected in Colombia, Brazil, Venezuela, India, and Philippines. Public health consequences, including vector-borne disease surges, engaged World Health Organization, national ministries such as Mexican Secretariat of Health, Ministry of Health of Peru, and programs by Centers for Disease Control and Prevention. Infrastructure damage mobilized reconstruction financing from Asian Development Bank, European Investment Bank, and United Nations Development Programme.

Monitoring, Forecasting, and Response

Real-time monitoring relied on networks and institutions including TAO/TRITON, ARGO, Global Ocean Observing System, NOAA Climate Prediction Center, European Centre for Medium-Range Weather Forecasts, Japan Meteorological Agency, and Bureau of Meteorology (Australia). Forecast models developed at National Center for Atmospheric Research, Geophysical Fluid Dynamics Laboratory, Met Office Hadley Centre, and university labs at Columbia University and University of Washington provided seasonal outlooks supporting decision-making by United Nations Framework Convention on Climate Change negotiators and national disaster management agencies like Federal Emergency Management Agency. Early warning initiatives involved Red Cross and Red Crescent Movement, bilateral aid from United States Agency for International Development, and capacity-building by Food and Agriculture Organization and World Bank disaster risk reduction programs.

Aftermath, Recovery, and Long-term Climate Implications

Post-event assessments by Intergovernmental Panel on Climate Change authors, National Research Council (United States), and research groups at Scripps Institution of Oceanography and Lamont–Doherty Earth Observatory informed improvements in coupled models and observational networks, influencing later responses to events such as the 2015–16 El Niño. Policy dialogues within United Nations Framework Convention on Climate Change and investments by Green Climate Fund and Global Environment Facility incorporated lessons on resilience from affected countries including Indonesia, Ecuador, Peru, Australia, and United States. Long-term impacts on climate variability, studied by scientists at California Institute of Technology, University of Oxford, Max Planck Institute for Meteorology, and Centre National de la Recherche Scientifique, continue to inform attribution studies linking extreme events to anthropogenic changes evaluated by Intergovernmental Panel on Climate Change assessments and national climate services.

Category:El Niño events