Despite the Paris Agreement target of holding global temperature increases 1.5 to 2°C above pre-industrial levels, high-end climate change (HECC) scenarios going beyond 4°C are becoming increasingly plausible. HECC may imply increasing climate variability and extremes as well as the triggering of tipping points, posing further difficulties for adaptation.

This paper compares the outcomes of four concurrent European case studies (EU, Hungary, Portugal and Scotland) that explore the individual and institutional conditions, and the information used to underpin adaptation-related decision-making in the context of HECC. The focus is on (i) whether HECC scenarios are used in current adaptation-related decision-making processes; (ii) the role of uncertainty and how climate and non-climate information is used (or not) in these processes; and (iii) the information types (including socio-economic drivers) commonly used and their limitations in relation to HECC scenarios.

Decision-makers perceive HECC as having a low probability or distant occurrence and do not routinely account for HECC scenarios within existing climate actions. They also perceive non-climate drivers as at least as important as, in many cases more important than, climate change alone.

While more information about the implications of particular sectoral and cross-sectoral impacts is needed, climate change uncertainty is not a significant barrier to decision-making. Further understanding of individual and institutional challenges brought about by the “squeeze” between adapting to HECC scenarios or to lower levels of temperature change (like those agreed in Paris) is essential to better contextualise the use of climate change information.

This paper is affiliated to the IMPRESSIONS project.