Practical work in environment-dependent livelihoods is often determined by daily weather and other environmental conditions. Identification and classification of these conditions, as well as rendering them in terms that fit into the earth-system modelling framework, are imperative for providing useful information to practitioners for the development of adaptation and mitigation strategies that are applicable now and in the future. We use reindeer herding as a showcase of an environment-dependent livelihood, illustrating the steps taken to produce relevant information on possible future challenges for the livelihood determined by climate change. This showcase is a cross-disciplinary work, based on an ongoing co-creation of knowledge process with reindeer herders in Fennoscandia, where this talk focusses on the earth-system modeller’s perspective. From a combination of the operational system of reindeer herding and meteorological seasonality, we developed a range of critical events in the reindeer herding year that influence the success of this livelihood. We tried to find – sometimes unsuccessfully - descriptions of these events as combinations of specific meteorological conditions (climate indices), so we can compute them from earth-system model output, and then identified data sets that could be used to calculate these climate indices. In this process, we found that some of the climate indices can be computed relatively easily and with confidence, while for others, there are obstacles caused by lack of knowledge on how to relate local knowledge to modelling, lack of data availability, or lack of confidence in available data, which have to be addressed within the modelling community.