Corals and Short-term
Climate Variability:


Photo courtesy of M. Neimer, NOAA Pacific Marine Environmental Laboratory (PMEL).

Modern observational equipment such as this TOGA-TAO buoy provide us with important information about what is happening to the climate now. However, in order to understand how the system operates, we need a long record of observations. Corals and other recorders of past climate are essential to understanding the full range of natural variability. Some of the corals shown on this website have yielded long and detailed records of sea surface temperature (SST).

This page includes a description of the El Niño/Southern Oscillation (ENSO) phenomenon, which is one of the dominant forcing mechanisms behind modern day short-term climate variability. Although its development is very localized, the climatic impacts of ENSO are experienced on a global scale. Since instrumental data are limited, scientists must use paleoclimate records (from corals, ice cores, tree rings, etc.) to study past climate variability in an attempt to better understand ENSO and its role in modern day climate variability.

What is El Niño?

El Niño-Southern Oscillation (ENSO) refers to a coupled oceanic and atmospheric phenomenon known to be a central factor in short-term climate variability. As shown here, remarkable differences are observed in the tropical Pacific during the cool phase as compared with the warm phase of ENSO.

Graphic produced by Thomas Andrews using information from Cole (1992), The Open University (1989), and Wallace and Vogel (1994).

Graphic produced by Dr. Robert Dunbar, Stanford University.


During the ENSO warm phase, abnormal warming of the ocean surface covers the equatorial Pacific from South America to the dateline. This causes changes in the global atmospheric circulation and associated rainfall distribution. There is a strong relationship between ENSO and climate in many parts of the world.

Global Impacts of ENSO:

Climate variations associated with ENSO often have widespread and devastating impacts, including the occurrence of short-term regional drought and flooding in many parts of the world. This diagram depicts many of the areas believed to be impacted by ENSO.

Graphic produced by Thomas Andrews using information from Wells (1990), Ropelewski and Halpert (1987), and Sharp (1992).

ENSO headlines collage courtesy of Bree Thompson, NOAA Office of Global Programs.

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Coral Paleoclimatology website by Heather Benway, NOAA Office of Global Programs, hosted by the NOAA Paleoclimatology Program. Please contact us if you have any comments and/or suggestions.