Figure 1 Global annual mean temperatures from 1860 to 1998. Shown (in terms of degrees C or F, at left and right) is the difference (or "temperature anomaly") between each annual mean temperature and the average for the 30-year period from 1961 to 1990. (Courtesy James Hurrell; adapted from data provided by the Hadley Center, United Kingdom Meteorological Office, and the Climate Research Unit, University of East Anglia, Norwich, England).