Before contacting us, please check if your question about the GISTEMP analysis is already answered in the FAQ. Temperature analyses were carried out prior to 1980, notably those of Murray Mitchell, but most covered only 20-90°N latitudes. 1981) showed that, contrary to impressions from northern latitudes, global cooling after 1940 was small, and there was net global warming of about 0.4°C between the 1880s and 1970s.
See the Updates to Analysis page for detailed update information. This fact proved sufficient to obtain useful estimates for global mean temperature changes.This was done by sampling at station locations a spatially complete data set of a long run of a global climate model, which was shown to have realistic spatial and temporal variability.This however only addresses the error due to incomplete spatial coverage of measurements.The GISS Surface Temperature Analysis (GISTEMP) is an estimate of global surface temperature change. In citing the webpage, be sure to include the date of access.Graphs and tables are updated around the middle of every month using current data files from NOAA GHCN v3 (meteorological stations), ERSST v5 (ocean areas), and SCAR (Antarctic stations), combined as described in our December 2010 publication (Hansen et al. These updated files incorporate reports for the previous month and also late reports and corrections for earlier months. 15, 2017: The standard GISTEMP analysis now uses the ERSST version 5 dataset for sea surface temperatures, rather than ERRST v. June 15, 2017: We have added an interactive version of the seasonal cycle plot to the Graphs page. 19, 2017: The separate pages for creating plots of "time series of zonal means" and "seasonal cycle of zonal means" have been combined as a single page for making Plots of Zonal Means. The basic GISS temperature analysis scheme was defined in the late 1970s by James Hansen when a method of estimating global temperature change was needed for comparison with one-dimensional global climate models.