Glacial ice cores are evidence of past environmental conditions through gases and particulate matter trapped within the drilled material. The Central Andes in the South American region are highly sensitive to climate changes; a long record of temperature and precipitation variability can be found in relation to massive ice caps. Available oxygen isotope data from three glacial ice cores from Nevados Sajama, Huascaran and Illimani (Peru and Bolivia) drilled over the last decades in the Central Andes are revisited to investigate climate variability over the past seven millennia, a period characterized globally by remarkable climatic stability. The analysis revealed statistically significant millennial- and centennial-scale periodicities in the isotope records ranging from centennial to millennial timescales. These cycles have periods of 1.3, 0.87, 0.67, 0.46, and 0.25 kiloyears (ka). A series of regional temperature minima and maxima are also identified. This variability in the Andean climate during the mid and late Holocene is interpreted as being strongly controlled by changes in solar activity, in particular, the forcing of “grand solar minima” is recognized. Likewise, less frequent climate changes could be correlated with Bond cycles and increased or decreased activity of the Atlantic Meridional Overturning Circulation (also known as AMOC or the thermohaline), among other climate forcings such as volcanic activity.

Scientific projects and initiatives are typically designed around scientific excellence and technical capability, treating policy relevance as a secondary consideration rather than a design driver. This places primary emphasis on outputs, assuming that scientific robustness alone is sufficient to ensure their uptake in policy processes. In practice, decision-makers are a diverse set of actors operating under different mandates, timeframes, legal responsibilities, and risk considerations, all of which condition whether and how scientific knowledge can be used to inform their decisions. Drawing on experience from the EU-funded Geological Service for Europe (GSEU) project, we argue that effective geoscience-policy engagement starts with clearly identifying who the outputs are for and how these actors define usable knowledge.GSEU brings together European Geological Survey Organisations to provide harmonised subsurface data, information, tools, and knowledge at continental scale. In doing so, it offers an opportunity to explore the challenges and opportunities of engaging with EU institutions, which constitute the project’s main target audience. We reflect on lessons learned from attempting to align scientific outputs with specific decision contexts, including those related to critical raw materials and CO2 storage.We highlight the importance of early identification of key actors, mapping their needs and expectations, continuous dialogue with stakeholders working at the science-policy interface, and iterative adaptation of scientific outputs to decision-makers’ needs. We also discuss some of the challenges, such as communicating uncertainty and navigating the mismatch between scientific and policy timelines.By arguing for a focus on the “who” before the “what,” we aim to provide transferable insights for geoscientists seeking to engage more effectively in policy design.