If it felt like this past year was hotter than usual, you were not imagining things. According to independent analyses by NASA and the National Oceanic and Atmospheric Administration (NOAA), Planet Earth’s surface temperatures during 2016 were the warmest since modern recordkeeping began in 1880.
This finding makes 2016 the third year in a row to set a new record for global average surface temperatures and continues what has been a long-term warming trend. Globally-averaged temperatures in 2016 were 1.78°F warmer than the mid-20th century mean.
The planet’s average surface temperature has risen about 2°F since the late 19th century. Reasons behind the change are up for debate.
Most of the warming occurred in the past 35 years, with 16 of the 17 warmest years on record occurring since 2001.
Not only was 2016 the warmest year on record, but eight of the 12 months that make up the year — from January through September, with the exception of June — were the warmest on record for those respective months. October, November, and December of 2016 were the second warmest of those months on record — in all three cases, behind records set in 2015.
Factors to Consider
A warming El Niño event was in effect for most of 2015 and the first third of 2016. Researchers estimate the direct impact of the natural El Niño warming in the tropical Pacific increased the annual global temperature anomaly for 2016 by 0.2°F.
Weather dynamics often affect regional temperatures, so not every region on Earth experienced record average temperatures last year. For example, both NASA and NOAA found the 2016 annual mean temperature for the contiguous U.S. was the second warmest on record. In contrast, the Arctic experienced its warmest year ever, consistent with record low sea ice found in that region for most of the year.
How is the Data Gathered?
NASA’s analyses incorporate surface temperature measurements from 6,300 weather stations, ship- and buoy-based observations of sea surface temperatures, and temperature measurements from Antarctic research stations. These raw measurements are analyzed using an algorithm that considers the varied spacing of temperature stations around the globe and urban heating effects that could skew the conclusions. The result of these calculations is an estimate of the global average temperature difference from a baseline period of 1951 to 1980.
NOAA scientists used much of the same raw temperature data, but with a different baseline period, and different methods to analyze Earth’s polar regions and global temperatures.