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2017 Was the Second Hottest Year on Record

2017 Temperature Anomaly (Degrees Celsius)

Earth’s global surface temperatures in 2017 ranked as the second warmest since 1880, according to an analysis by scientists at NASA’s Goddard Institute for Space Studies (GISS). Continuing the planet’s long-term warming trend, globally averaged temperatures in 2017 were 0.90 degrees Celsius (1.62 degrees Fahrenheit) warmer than the 1951 to 1980 mean. That is second only to global temperatures in 2016.

In a separate, independent analysis, scientists at the National Oceanic and Atmospheric Administration (NOAA) concluded that 2017 was the third-warmest year in their record. The minor difference in rankings is due to slightly different methods used by the two agencies to analyze global temperatures. The long-term records of the two agencies remain in strong agreement, and both analyses show that the five warmest years on record have all taken place since 2010.

The map above depicts global temperature anomalies in 2017, according to the NASA GISS team. The map does not show absolute temperatures; instead, it shows how much warmer or cooler each region of Earth was compared to a baseline average from 1951 to 1980.

Because the locations and measurement practices of weather stations change over time, there are uncertainties in the interpretation of specific year-to-year global mean temperature differences. Taking this into account, NASA estimates that the 2017 global mean change is accurate to within 0.1 degree Fahrenheit, with a 95 percent certainty level.