From http://www.ncdc.noaa.gov/ol/climate/research/1998/anomalies/anomalies.html#files Global Long-term Mean Land and Sea Surface Temperatures Matt Menne March 15, 2000 Estimates of mean monthly global surface temperatures are given below with respect to the long-term period 1880 to 1999. The figures are based on 1961-1990 estimates from the University of East Anglia?s Climate Research Unit (UEA-CRU). The recently derived 1961-1990 global monthly surface temperature averages represent, in our opinion, the best absolute estimates of global mean temperature and were compiled at UEA-CRU by M. New, P.D. Jones, D.E. Parker and others . The data and methods used are described here and in current and forthcoming publications (see below). The UEA-CRU 1961-1990 estimates have been separated into land and sea components and adjusted using the longer-term global temperature anomaly time series from NCDC. The figures presented below therefore are mean monthly global surface temperature estimates for the entire period of reliable temperature records, 1880 to 1999. Estimates for land (including Antarctica) and sea surface areas for the period 1880 to 1999 are given separately and in combined form. Absolute estimates of global mean surface temperature are difficult to compile for a number of reasons. Since some regions of the world have few temperature measurement stations (e.g., the Sahara Desert), interpolation must be made over large, data sparse regions. In mountainous areas, most observations come from valleys where the people live so consideration must be given to the effects of elevation on a region?s average as well as to other factors that influence surface temperature. Consequently, the estimates below, while considered the best available, are still approximations and reflect the assumptions inherent in interpolation and data processing. Time series of monthly temperature records are more often expressed as departures from a base period (e.g., 1961-1990, 1880-1999) since these records are more easily interpreted and avoid some of the problems associated with estimating absolute surface temperatures over large regions. For a brief discussion of using temperature anomaly time series see the Climate of 1998 series. The global monthly surface temperature averages in the table below can be added to a given month? s anomaly (departure from the 1880 to 1999 base period average) to obtain an absolute estimate of surface temperature for that month. (Files of absolute estimates are provided below.) Global Mean Monthly Surface Temperature Estimates for the Base Period 1880 to 1999 Land Surface Mean Temp. JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Annual 1880 to 1999 (C) 2.7 3.1 4.9 8.1 11.1 13.2 14.3 13.8 12.0 9.3 5.9 3.6 8.5 1880 to 1999 (F) 36.8 37.6 40.8 46.5 51.9 55.8 57.8 56.9 53.6 48.7 42.6 38.5 47.3 Sea Surface Mean Temp. JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Annual 1880 to 1999 (C) 15.8 15.9 15.9 16.0 16.3 16.4 16.4 16.4 16.2 15.9 15.8 15.7 16.1 1880 to 1999 (F) 60.5 60.6 60.7 60.9 61.3 61.5 61.5 61.4 61.1 60.6 60.4 60.3 60.9 Combined Mean Surface Temp. JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Annual 1880 to 1999 (C) 12.0 12.1 12.7 13.7 14.8 15.5 15.8 15.6 15.0 14.0 12.9 12.2 13.9 1880 to 1999 (F) 53.6 53.9 54.9 56.7 58.6 59.9 60.4 60.1 58.9 57.2 55.2 54.0 56.9 Erratum: Please note that prior to 26 June 2000, the mean values added to the land and ocean anomalies were incorrect. These data are now correct. Analysis of trends in the time series would not be impacted by this error since the error involved adding a constant to the entire period of record. The complete land-sea surface climatology from the Climate Research Unit is described in: Jones, P. D., M. New, D. E. Parker and S. Martin, submitted: Surface air temperature and its changes over the past 150 years. Rev. Geophys. This climatology is actually a combination of four separate data sets: Global land areas, excluding Antarctica, described in: New, M. G., M. Hulme and P. D. Jones, in press: Representing 20th century space-time climate variability. I: Development of a 1961-1990 mean monthly terrestrial climatology. J. Climate. Global oceans, 60S-60N, described in: Parker, D. E., M. Jackson and E. B. Horton, 1995: The GISST2.2 sea surface temperature and sea-ice climatology. Climate Research Technical Note, CRTN 63, Hadley Centre for Climate Prediction and Research, Bracknel, UK. Arctic sea areas, described in: Rigor, I. G., R. L. Colony and S. Martin, submitted: Statistics of surface air temperature observations in the Arctic. J. Climate. Martin, S. and E.A. Munoz: Properties of the Arctic 2-Meter Air temperature field for 1979 to the present derived from a new gridded data set. J. Climate, 10, 1428-1440. The Global Anomalies and Index As data are being received, scientists at The National Oceanic and Atmospheric Administration's National Climatic Data Center are automatically updating The Global Historical Climatology Network data base to maintain a global climate perspective in near real-time. The Monthly Global Land Temperature Anomalies (degrees C) The Monthly Global Land Temperature Anomalies (degrees F) The Monthly Global Ocean Temperature Anomalies (degrees C) The Monthly Global Ocean Temperature Anomalies (degrees F) The Monthly Global (land and ocean combined into an anomaly) Index (degrees C) The Monthly Global (land and ocean combined into an anomaly) Index (degrees F) The Annual Global Land Temperature Anomalies (degrees C) The Annual Global Ocean Temperature Anomalies (degrees C) The Annual Global (land and ocean combined) Anomalies (degrees C) ...through the most recent complete year (2000). The Monthly Absolute Estimates of Global Land Temperature (degrees C) The Monthly Absolute Estimates of Global Land Temperature (degrees F) The Monthly Absolute Estimates of Global Ocean Temperature (degrees C) The Monthly Absolute Estimates of Global Ocean Temperature (degrees F) The Monthly Absolute Estimates of Global (land and ocean combined) Temperature Index (degrees C) The Monthly Absolute Estimates of Global (land and ocean combined) Temperature Index (degrees F) EOF