Origin, governance and evolution of the Essential Climate Variables framework managed by the Global Climate Observing System (GCOS)

The need to understand how climate is changing has never been greater, and we cannot understand what we do not observe. This contribution will describe the origin and evolution of a set of essential climate variables (ECVs) that are managed by the Global Climate Observing System (GCOS) programme, through its three expert panels for the atmospheric, oceanic and terrestrial domain. The ECVs constitute the minimum set of observations required to systematically observe the Earth’s changing climate across three domains: the ocean, land and atmosphere. ECVs have facilitated the implementation of the observing system through a user-driven process, guiding investment decisions, and mobilizing climate observing communities. The first set of Essential Climate Variables were developed by GCOS in the late 1990’s and since then the list has grown to the 55 current ECVs. After 25 years, GCOS has started a process aimed at the rationalization of the ECV list. In this contribution, the main outputs of this rationalization process will be presented: (1) formalization of a governance process to adopt new ECVs; (2) revised definitions for ECVs and ECV quantities; (3) a proposal for an updated set of ECVs. The connections between the ECV framework and other frameworks such as the Essential Ocean Variables framework will also be covered.