Global temperature is calculated as an average of air temperature recordings from land weather stations, sea surface measurements from ships and buoys, and increasingly, satellite data. To produce reliable estimates, scientists convert raw temperature readings into anomalies—differences from long-term average temperatures for specific locations—because anomalies are more consistent across large areas than absolute temperatures. The Earth’s surface is divided into grid cells where individual anomalies are averaged, weighted by the area each grid cell represents, to calculate a global average. Since some regions, like polar areas, have sparse measurement coverage, estimates for missing data are made using statistical methods and satellite observations. This comprehensive method allows tracking of global temperature trends; for example, the decade between 2006 and 2015 was the warmest on record since modern thermometers began recording about 150 years ago.
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