It’s not just a presumption and it isn’t media just “pushing this.”

https://climate.nasa.gov/vital-signs/global-temperature/

> Nineteen of the warmest years have occurred since 2000, with the exception of 1998. The year 2020 tied with 2016 for the warmest 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.