This graph illustrates the change in global surface temperature relative to 1951-1980 average temperatures. The 1.18°C temperature increase displayed on our home page represents global temperature change since 1880. One gets this number by taking the difference between 1.02 (2020) and -0.16 (1880).
Nineteen of the hottest years have occurred since 2000, with the exception of 1998, which was helped by a very strong El Niño. The year 2020 tied with 2016 for the hottest year on record since record-keeping began in 1880 (source: NASA/GISS). This research is broadly consistent with similar constructions prepared by the Climatic Research Unit and the National Oceanic and Atmospheric Administration.