Community needs for Observations to constrain Earth System Models

Observations are key for development of earth and environmental systems models. They can be used for initialisation, verification and evaluation, forcing, constraining and benchmarking. Providing the observed variables required by modellers in a useful format with necessary metadata, including uncertainty characterisation, has traditionally not been seen as the responsibility of the observation providers. This has caused a mismatch between what is provided and what is required, leading to proxy climate data such as reanalyses being widely used in place of true observations. To enhance the uptake and usability of observational datasets, they should be provided with easy access, in easy to use format, clearly documented and with detailed metadata.The Working Group on Observations for Researching Climate (WGORC) was set up in 2025 by the World Climate Research Program (WCRP) Earth System Modelling and Observations (ESMO) core project. WGORC kicked off in December 2025 and is focused on improving the use of observations throughout climate science, addressing the mismatch mentioned above and ensuring correct use and application of observations to model development.ESMO working groups function through the activities of panels and task teams which are set up in response to identified needs. WGORC has one existing panel and will be looking to set up at least two more based on the outcomes of the scoping activities currently underway.The initial WGORC focus areas include:* Characterisation and communication of observational uncertainties * Use of observations in machine learning applications for climate * Observations to better understand and model extreme weather and climate events * Data rescue and recovery of historical climate observations The existing panel, obs4MIPs, is an ongoing community-driven initiative to provide observational datasets in the format to support model benchmarking and evaluation of Earth System Models as part of the Climate Model Intercomparison Projects (CMIP). This presentation will describe WGORC in detail and outline the scoping activities in the four focus areas and the ongoing activities of the existing panel obs4MIPs which is currently investigating how to expand its offering to provide point observations as well as gridded, and the provision of associated uncertainty data with each dataset. It will also discuss opportunities on how the community can stay engaged with WGORC and ESMO activities and be consulted during user requirements gathering for climate observations.