Climate Change: Global Temperature

Author: 
September 11, 2017

Temperatures measured on land and at sea for more than a century show that Earth's globally averaged surface temperature is rising. Since 1970, global surface temperature rose at an average rate of about 0.17°C (around 0.3° Fahrenheit) per decade—more than twice as fast as the 0.07°C per decade increase observed for the entire period of recorded observations (1880-2015). The average global temperature for 2016 was 0.94°C (1.69°F) above the 20th century average of 13.9°C (57.0°F), surpassing the previous record warmth of 2015 by 0.04°C (0.07°F).

global temperature map 2016

Average surface temperature in 2016 compared to the 1981-2010 average. NOAA Climate.gov map, adapted from Plate 2.1a in State of the Climate in 2016.

Change over time

Though warming has not been uniform across the planet, the upward trend in the globally averaged temperature shows that more areas are warming than cooling. Since 1880, surface temperature has risen at an average pace of 0.13°F (0.07°C) every 10 years for a net warming of 1.69°F (0.94°C) through 2016. Over this 137-year period, average temperature over land areas has warmed faster than ocean temperatures: 0.18°F (0.10°C) per decade compared to 0.11°F (0.06°C) per decade.  The last year with a temperature cooler than the twentieth-century average was 1976. 

History of global surface temperature since 1880

Explore this interactive graph: Click and drag to display different parts of the graph. To squeeze or stretch the graph in either direction, hold your Shift key down, then click and drag. The graph shows average annual global temperatures since 1880  (source data) compared to the long-term average (1901-2000). The zero line represents the long-term average temperature for the whole planet; blue and red bars show the difference above or below average for each year.

According to the official 2016 global report from NOAA's National Centers for Environmental Information,

[2016]  marks the fifth time in the 21st century a new record high annual temperature has been set (along with 2005, 2010, 2014, and 2015) and also marks the 40th consecutive year (since 1977) that the annual temperature has been above the 20th century average. To date, all 16 years of the 21st century rank among the seventeen warmest on record (1998 is currently the eighth warmest.) The five warmest years have all occurred since 2010.

By 2020, models project that global surface temperature will be more than 0.5°C (0.9°F) warmer than the 1986-2005 average, regardless of which carbon dioxide emissions pathway the world follows. This similarity in temperatures regardless of total emissions is a short-term phenomenon: it reflects the tremendous inertia of Earth's vast oceans. The high heat capacity of water means that ocean temperature doesn't react instantly to the increased heat being trapped by greenhouse gases. By 2030, however, the heating imbalance caused by greenhouse gases begins to overcome the oceans' thermal inertia, and projected temperature pathways begin to diverge, with unchecked carbon dioxide emissions likely leading to several additional degrees of warming by the end of the century.

About surface temperature

The concept of an average temperature for the entire globe may seem odd. After all, at this very moment, the highest and lowest temperatures on Earth are likely more than 100°F (55°C) apart. Temperatures vary from night to day and between seasonal extremes in the Northern and Southern Hemispheres. This means that some parts of Earth are quite cold while other parts are downright hot. To speak of the "average" temperature, then, may seem like nonsense. However, the concept of a global average temperature is convenient for detecting and tracking changes in Earth's energy budget—how much sunlight Earth absorbs minus how much it radiates to space as heat—over time.

To calculate a global average temperature, scientists begin with temperature measurements taken at locations around the globe. Because their goal is to track changes in temperature, measurements are converted from absolute temperature readings to temperature anomalies—the difference between the observed temperature and the long-term average temperature for each location and date. Multiple independent research groups across the world perform their own analysis of the surface temperature data, and they all show a similar upward trend. 


Annual surface temperature compared to the 1981-2010 average from multiple, independent research groups. NOAA Climate.gov graph adapted from Figure 2.1a in State of the Climate in 2016. 

Across inaccessible areas that have few measurements, scientists use surrounding temperatures and other information to estimate the missing values. Each value is then used to calculate a global temperature average. This process provides a consistent, reliable method for monitoring changes in Earth's surface temperature over time. Read more about how the global surface temperature record is built in our Climate Data Primer.

References

NOAA National Centers for Environmental Information, State of the Climate: Global Analysis for Annual 2016, published online January 2017, retrieved on September 11, 2017 from https://www.ncdc.noaa.gov/sotc/global/201613.

IPCC, 2013: Summary for Policymakers.  In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group 1 to the 5th Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.

R. J. H. Dunn, D. F. Hurst, N. Gobron, and K. M. Willett, Eds., 2017: Global Climate [in “State of the Climate in 2016”]. Bull. Amer. Meteor. Soc., 98 (8), S5–S62, doi:10.1175/2017BAMSStateoftheClimate.1.

Interactive graph data

Annual global temperature anomalies for land and ocean combined, expressed as departures from the 1901-2000 average. National Climatic Data Center.

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