Lessons in climate service development from Klimaatlas, the Danish National Climate Atlas.

Responding to the challenges of a changing climate requires information that is relevant and actionable at the local scale where adaptation actions take place. To address these needs within Denmark, Klimaatlas, the Danish National Climate Atlas, was developed to provide information to ministries, regional authorities, businesses and citizens about climate change in Denmark.  Here we present the lessons learnt since the inception of the project in 2018, with a focus on those that are relevant to the development of similar tools in other regions. We will examine issues around the conception and setup of the climate service, particularly the need to identify users, work with champions and set limits. Communication is a critical aspect of such a service and we will discuss our approach of communicating on multiple levels, and taking up the challenge of uncertainty. Updatability, maintenance and operationalisation are also key, and the merits of the “rolling-releases” model used by Klimaatlas will be discussed, together with our efforts to open our codebase via the KAPy project. Finally, we discuss issues around future maintenance and possible expansions of Klimaatlas, including the use of convection permitting simulations, incorporation of compound events, updates between IPCC cycles and extensions to new sectors.