This figure shows the difference in instrumentally determined surface temperatures between the period January 1999 through December 2008 and "normal" temperatures at the same locations, defined to be the average over the interval January 1940 to December 1980. The average increase on this graph is 0.48 °C, and the widespread temperature increases are considered to be an aspect of global warming.

Data source

This plot is based on the NASA GISS Surface Temperature Analysis (GISTEMP), which combines the 2001 GISS land station analysis data set (Hansen et al. 2001) with the Rayner/Reynolds oceanic sea surface temperature data set (Rayner 2000, Reynolds et al. 2002). The data itself was prepared through the GISTEMP online mapping tool, and the specific dataset used is available here. This data was replotted in a Mollweide projection with a continuous and symmetric color scale. The smoothing radius is 1200 km, meaning that the reported temperature may depend on measurement stations located up to 1200 km away, if necessary.

Related images

• 
  "Global cooling" of 1965-74

Copyright

This figure was prepared by Robert A. Rohde from public domain data and is incorporated into the Global Warming Art project.

Image from Global Warming Art

This image is an original work created for Global Warming Art. Please refer to the image description page for more information.

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References

1. Hansen, J., R. Ruedy, M. Sato, M. Imhoff, W. Lawrence, D. Easterling, T. Peterson, and T. Karl (2001). "A closer look at United States and global surface temperature change". J. Geophys. Res 106: 23947-23963.
2. Rayner, N. (2000) HadISST1 Seaice and sea surface temperature files. Hadley Center, Bracknell, U.K.
3. Reynolds, R.W., N.A. Rayner, T.M. Smith, D.C. Stokes, and W. Wang (2002). "An improved in situ and satellite SST analysis for climate". J. Climate 15: 1609-1625. doi:10.1175/1520-0442(2002)015<1609:AIISAS>2.0.CO;2

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derivative works

Derivative works of this file:  Climate-change-template.jpg

• File:Global Warming Map-he.jpg
• File:Opwarming van de Aarde map.png