Climate observations are sourced from numerous meteorological and related observational networks and systems throughout the world.

To describe the whole climate system, we need to collect observations of the atmosphere, ocean and land-based systems.

Not all climate observations are the same and some are considered of higher quality than others. Therefore, a climate observation should be associated – either directly or indirectly – with a set of data (Metadata) describing the conditions in which the climate observations were collected and that will provide users with information, often implicitly, on how the observations should be interpreted and used.

There are over 11,000 weather stations around the world measuring land, air and sea temperatures, as well as satellites, ships and aircraft that also take measurements. The stations all follow strict standards and 1040 of these stations have been selected to provide high quality climate data to quantify and detect global aspects of climate change.