In earth science, the global surface temperature is calculated by averaging the temperature at the surface of the sea and air temperature over land. In technical writing, scientists call long-term changes in GST global cooling or global warming. Periods of both have happened regularly throughout earth's history. The global average temperature has warmed by 1.09°C (range: 0.95 to 1.20°C) from 1850–1900 to 2011–2020.