Recent GHG emissions trends are in stark contrast with the Paris Agreement’s target to hold the increase in average global warming to “well below 2 °C and pursue efforts to stay below 1,5 °C” by the end of the century compared with preindustrial times. This disconnect has further unveiled the limitations of current knowledge production and communication processes in Southern European countries, where fast institutional changes are needed to address the potential impacts as well as the opportunities for transformation derived from High-End Climate Change (HECC). The prevailing knowledge deficit-model – aimed at producing ‘more knowledge’ about climate impacts, vulnerabilities and long-term scenarios to decision makers – has long proven inadequate in tackling the many complexities of the present socio-climate quandary. The growing emphasis on assessing and implementing concrete solutions, demand new and more complex forms of agent interactions in the production, framing, communication and use of climate knowledge; and in particular, explicit procedures able to tackle difficult normative questions regarding assessment of solutions and the allocation of individual and collective responsibilities. To explore these challenges, we analyse the views of 30 Spanish knowledge contributors and users of the latest UN IPCC AR5 report and share the insights gained from the implementation of a participatory Integrated Assessment procedure aimed at developing innovative solutions to high-end climate scenarios in Iberia. Our analysis supports the view of the need to institutionalise transformation, and in particular underlines the potential role that transformative climate boundary organisations could play to address such difficult ethical choices in different contexts of action.