To start with many of the most reliable weather stations are globally located at airports. Airports that are selected to be located at the sunniest, best VFR conditions and least foggy places available if there is a choice. If you measure there, at dry and sunny places with large aprons and runways being easier warmed up by sunlight, it feels like the world would be warmer and closer to heating up compared to if you had picked a more neutral selection of places without aviation weather needs.
You don’t seriously believe this is where data is collected from to inform scientists on climate monitoring, do you? The whole debate based on METARs.....