César Mösso Aranda

Climate Impact Assessments

This chapter highlights key climate impacts, hazards and vulnerabilities and associated indicators that have been used to assess current (recent) climate impacts at each of the case-study sites. The aim is to illustrate some of the wide range of information available from individual case studies and highlight common themes that are evident across multiple case-study locations. This is used to demonstrate linkages and sensitivities between the specific climate impacts of relevance for each case-study type (urban, rural and coastal) and the key climate hazards and biogeophysical and social vulnerabilities representing the underlying drivers and site conditions. For some impacts, there are clear, direct links with climate events, such as heat stress and flooding, while for others, such as energy supply and demand, the causal relationships are more indirect, via a cascade of climate, social and economic influences. Water availability and extreme temperatures are common drivers of current climate impacts across all case studies, including, for example, freshwater supply and heat stress for urban populations; irrigation capacity and growing season length for agricultural regions; and saltwater intrusion of aquifers and tourist visitor numbers at coastal locations. At some individual case-study locations, specific impacts, hazards and/or vulnerabilities are observed, such as peri-urban fires in Greater Athens, infrastructure vulnerability to coastal flooding in Alexandria, groundwater levels in Tel Hadya and vector-borne diseases in the Gulf of Oran. Throughout this chapter, evidence of current climate impacts, hazards and vulnerabilities from each of the case studies is detailed and assessed relative to other case studies. This provides a foundation for considering the wider perspective of the Mediterranean region as a whole, and for providing a context from which to assess consequences of future climate projections and consider suitable adaptation options.

Integration of the Climate Impact Assessments with Future Projections

Climate projections are essential in order to extend the case-study impacts and vulnerability assessments to encompass future climate change. Thus climate-model based indicators for the future (to 2050 and for the A1B emissions scenario) are presented for the climate and atmosphere theme (including indices of temperature and precipitation extreme events), together with biogeophysical and socioeconomic indicators encompassing the other case-study themes. For the latter, the specific examples presented here include peri-urban fires, air pollution, human health risks, energy demand, alien marine species and tourism (attractiveness and socio-economic consequences). The primary source of information about future climate is the set of global and regional model simulations performed as part of CIRCE. These have the main novel characteristic of incorporating a realistic representation of the Mediterranean Sea including coupling between sea and atmosphere. These projections are inevitably subject to uncertainties relating to unpredictability, model structural uncertainty and value uncertainty. These uncertainties are addressed by taking a multi-model approach, but problems remain, for example, due to a systematic cold bias in the CIRCE models. In the context of the case-study integrated assessments, there are also uncertainties ‘downstream’ of climate modeling and the construction of climate change projections – largely relating to the modeling of impacts. In addition, there are uncertainties associated with all socio-economic projections used in the case studies – such as population projections. Thus there are uncertainties inherent to all stages of the integrated assessments and it is important to consider all these aspects in the context of adaptation decision making.

Synthesis and the Assessment of Adaptation Measures

The final stage of the CIRCE case-studies integrated assessment involved identification and evaluation of the effectiveness of local and regional adaptation options in collaboration with stakeholders, and in the context of wider national adaptation policies and strategies. This stage provides a synthesis of both the case-study work and the wider CIRCE project since it draws on the case-study indicators for present and future periods together with wider CIRCE work on adaptation options, particularly in the thematic areas of agriculture, forestry and ecosystems, and Mediterranean communities. This synthesis and evaluation links impacts and vulnerability with adaptation, and also benefits strongly from the local stakeholder workshops held towards the end of the project. Lessons learnt and key messages from the CIRCE case studies are presented. While the objectives of the CIRCE case studies have generally been achieved, a number of research gaps and needs remain.

Quantification of the tidal stream exergy in the ría de Vigo (NW Spain)

The exergy of the tidal currents in the ria de Vigo area (NW Spain) is quantified using the results of a 28-day long simulation of the tidal flows. The results show that the northernmost strait connecting the ria with the Atlantic Ocean is a promising site for tidal energy tapping, in contrast with the energetically weaker estuary. On the basis of the average power density (APD), a 7.5 km2 region is identified in this strait as the most advantageous area to install tidal energy converters (TECs), with a total annual exergy of around 3865 MWh/m2. Similar analyses using only 14-day simulations change this value in ±16%, depending on whether the tidal cycle considered is apogean or perigean. The study contributes to enlarge the inventory of sites along the NW Spanish coast at which tidal stream energy can be potentially extracted.