GISS Surface Temperature Analysis
Global Temperature Trends: 2003 Summation
The year 2003 is the third warmest year in the period of accurate instrumental data (since the late 1800s). The annual-mean global surface temperature is 0.51°C above the climatological mean (1951-1980 average) in the GISS analysis, which uses meteorological station measurements over land and satellite measurements of sea surface temperature over the ocean.
Figure 1 below shows that the warmest temperature occurred in 1998, while the second warmest year was 2002. As this figure shows, there has been a strong warming trend over the past 30 years, a trend that has been shown to be due primarily to increasing greenhouse gases in the atmosphere. El Niños, in which warm water spreads over the tropical Pacific Ocean, are one major cause of fluctuations about the long-term trend.
The map of surface temperature anomalies in 2003 (Figure 2) shows that the largest warm anomalies were in Siberia and in the Arctic. Averaged over the 12 months, most places in the world were warmer than normal, although the eastern half of the United States was slightly below normal.
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Figure 1: Trend of global annual surface temperature relative to 1951-1980 mean. Click for full-size PDF of this graph. | Figure 2: Global map of temperature anomalies for the year 2003 (Jan.-Dec.) relative to the 1951-1980 baseline. Click for full-size PDF of this map. |
The monthly mean maps shown below in Figure 3 show natural variability from month to month during the year.

Figure 3: Global map of monthly-mean temperature anomalies for the year 2003 relative to the 1951-1980 baseline. Click for full-size PDF of this map.
Further Information
Related webpages on the GISS website include:
- GISS Surface Temperature Analysis (GISTEMP)
- Global Temperature Annual Summations: 2005, 2004, 2002, 2001.
References
- Christy, J.R., R.W. Spencer, and W.D. Braswell 2000. MSU Tropospheric Temperatures: Dataset Construction and Radiosonde Comparisons J. Atmos. Oceanic Tech. 17, 1153-1170.
- 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.
- Intergovernmental Panel on Climate Change 2001. Climate Change 2001 (J.T. Houghton et al., Eds.), Cambridge Univ. Press, New York.
- National Research Council 2000. Reconciling Observations of Global Temperature Change. National Academy Press, Washington, DC, 85 pp.
- 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.
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