Global Climate Report - July 2017
Monthly temperature anomalies versus El Niño

« Global Climate Report - July 2017


Monthly temperature anomalies versus El Niño


The graphic below depicts the monthly global temperature anomalies — that is, each month compared its 20th century average — since 1980, and the influence of the El Niño - Southern Oscillation (ENSO) phenomenon. The height of the bar represents the global temperature anomaly for the month. The color of the bar represents the ENSO condition or "phase," as represented by the Oceanic Niño Index, or ONI (web page, data file), developed at NOAA's Climate Prediction Center.

Months colored in red had El Niño conditions present. Blue represents La Niña conditions. Those in gray show "ENSO Neutral" conditions, when neither La Niña nor El Niño was occurring. Distinguishing between the three phases is useful to see ENSO's impact on global temperature anomalies.

Several factors are readily apparent in the figure. First, nearly every month since 1980 has been above the 20th century average, and has generally warmed through the period. Second, El Niño conditions (those months in red) tend to be warmer than neighboring periods, and La Niña conditions (blue) tend to be cooler. Third, protracted El Niño episodes tend to warm through the event, while La Niña episodes tend to cool through the event. Fourth, there are exceptions to all of the above points. Notably, the eruption of Mt. Pinatubo in 1991 temporarily cooled the planet's surface for more than a year, even in spite of the otherwise warming influence of El Niño during much of that period.

Monthly global temperature anomalies since Jan 1980, with ENSO phase shown
Global monthly temperature anomalies, with ENSO phase in color.