Climate Change Information for Regional Impact and Risk Assessment in the Mediterranean area: a climatic impact-driver (CID) framework.

The increasing availability of reliable climate-change information at the regional scales is prompting an ever-growing demand for impact and risk indicators suitable for policy planning and implementation. As highlighted in IPCC AR6, the latter also benefit from the recent advances in attribution and sectoral vulnerability studies, which now enable to identify the most relevant climatic variables and to investigate their past and future trends, characterizing the response of both environmental and socio-economic systems to climate-induced stress. Climate services aim to complement and combine up-to-date scientific knowledge and bottom-up contributions, including stakeholder needs, interests and expectations, to deliver user-oriented information and enhance awareness, preparedness, risk reduction and recovery strategies. Recognizing that climate-proofing our societies cannot be further postponed, the IPCC proposed a synergistic “Climatic Impact-Driver (CID) Framework” as a tool to preliminarily foster and feed physical climate science applications whenever specific information is lacking on the context where climate-change-induced phenomena can emerge as hazardous, beneficial, or inconsequential. Within the generic category of “impact-drivers” (e.g., climate change, population growth, viral outbreaks, technological change, social conflict), IPCC AR6 defined CIDS as “physical climate system conditions (e.g., means, events, and extremes) that affect an element of society or ecosystems”, the extent of their impact depending on system tolerance across interacting elements and regions. Despite their being based on characteristics (intensity, frequency, duration, timing, and spatial extent) that solely depend on complex, scale-spanning physical processes, CIDs are designed to represent the perspective of the affected system or sectoral asset and to provide stakeholders with a more exhaustive and purposeful reckoning of changing, potentially threatening climate conditions. Such an approach allows to evaluate potential impacts and to inter-compare regions, helping prioritize adaptation strategies, while maintaining climate information neutrality until more complex, intrinsically local, risk assessments are conducted, hazard and system specific thresholds defined, and decision-making processes brought into being. 

There is a nearly unanimous scientific consensus that current climate in many regions of the Earth has already changed with respect to the early or mid-20th century and that climate change has already critically altered CID characteristics, shifting the magnitude, frequency, duration, seasonality and spatial extent of their associated impact indices and indicators. In particular, the Mediterranean basin is experiencing significant changes in temperature and precipitation patterns, which can affect vital economic and environmental sectors in the surrounding countries. Here, the need for systematic and inter-comparable assessments of the expected impacts is particularly urgent, and action prioritization calls for progressively zooming analyses across regional and local scales and across multiple hazards, ideally accounting for interactions and superpositions between both CIDs and sectors, as well as for sector tolerance thresholds. In this context, we present temperature and precipitation related CID indicators at the NUTS-1, NUTS-2 and NUTS-3 aggregation levels, derived from new high-resolution (5 km) climate projections over the Italian peninsula, for both present climate and future scenarios (SSP1-2.6, SSP2-4.5 and SSP5-8.5), as obtained by downscaling the corresponding global ERA5 and MPI-ESM1-2-HR driven CMIP6 experiments.