Rodrigo Rojas

Multi-hazard assessment in Europe under climate change

While reported losses of climate-related hazards are at historically high levels, climate change is likely to enhance the risk posed by extreme weather events. Several regions are likely to be exposed to multiple climate hazards, yet their modeling in a joint scheme is still at the early stages. A multi-hazard framework to map exposure to multiple climate extremes in Europe along the twenty-first century is hereby presented. Using an ensemble of climate projections, changes in the frequency of heat and cold waves, river and coastal flooding, streamflow droughts, wildfires and windstorms are evaluated. Corresponding variations in expected annual exposure allow for a quantitative comparison of hazards described by different process characteristics and metrics. Projected changes in exposure depict important variations in hazard scenarios, especially those linked to rising temperatures, and spatial patterns largely modulated by local climate conditions. Results show that Europe will likely face a progressive increase in overall climate hazard with a prominent spatial gradient towards south-western regions mainly driven by the rise of heat waves, droughts and wildfires. Key hotspots emerge particularly along coastlines and in floodplains, often highly populated and economically pivotal, where floods and windstorms could be critical in combination with other climate hazards. Projected increases in exposure will be larger for very extreme events due to their pronounced changes in frequency. Results of this appraisal provide useful input for forthcoming European disaster risk and adaptation policy.

Climate Impacts in Europe. The JRC PESETA II Project

The objective of the JRC PESETA II project is to gain insights into the sectoral and regional patterns of climate change impacts in Europe by the end of this century. The study uses a large set of climate model runs and impact categories (ten impacts: agriculture, energy, river floods, droughts, forest fires, transport infrastructure, coasts, tourism, habitat suitability of forest tree species and human health). The project integrates biophysical direct climate impacts into a macroeconomic economic model, which enables the comparison of the different impacts based on common metrics (household welfare and economic activity). Under the reference simulation the annual total damages would be around €190 billion/year, almost 2% of EU GDP. The geographical distribution of the climate damages is very asymmetric with a clear bias towards the southern European regions. More than half of the overall annual EU damages are estimated to be due to the additional premature mortality (€120 billion). Moving to a 2°C world would reduce annual climate damages by €60 billion, to €120 billion (1.2% of GDP).

Structured Coupling of Probability Loss Distributions: Assessing Joint Flood Risk in Multiple River Basins

Losses due to natural hazard events can be extraordinarily high and difficult to cope with. Therefore, there is considerable interest to estimate the potential impact of current and future extreme events at all scales in as much detail as possible. As hazards typically spread over wider areas, risk assessment must take into account interrelations between regions. Neglecting such interdependencies can lead to a severe underestimation of potential losses, especially for extreme events. This underestimation of extreme risk can lead to the failure of riskmanagement strategies when they are most needed, namely, in times of unprecedented events. In this article, we suggest a methodology to incorporate such interdependencies in risk via the use of copulas. We demonstrate that by coupling losses, dependencies can be incorporated in risk analysis, avoiding the underestimation of risk. Based on maximum discharge data of river basins and stream networks, we present and discuss different ways to couple loss distributions of basins while explicitly incorporating tail dependencies. We distinguish between coupling methods that require river structure data for the analysis and those that do not. For the later approach we propose a minimax algorithm to choose coupled basin pairs so that the underestimation of risk is avoided and the use of river structure data is not needed. The proposed methodology is especially useful for large-scale analysis and we motivate and apply our method using the case of Romania. The approach can be easily extended to other countries and natural hazards.

Social tipping points in global groundwater management

Groundwater is critical to global food security, environmental flows, and millions of rural livelihoods in the face of climate change1. Although a third of Earth’s largest groundwater basins are being depleted by irrigated agriculture2, little is known about the conditions that lead resource users to comply with conservation policies. Here we developed an agent-based model3,4 of irrigated agriculture rooted in principles of cooperation5,6 and collective action7 and grounded on the World Values Survey Wave 6 (n = 90,350). Simulations of three major aquifer systems facing unsustainable demands reveal tipping points where social norms towards groundwater conservation shift abruptly with small changes in cultural values and monitoring and enforcement provisions. These tipping points are amplified by group size and best invoked by engaging a minority of rule followers. Overall, we present a powerful tool for evaluating the contingency of regulatory compliance upon cultural, socioeconomic, institutional and physical conditions, and its susceptibility to change beyond thresholds. Managing these thresholds may help to avoid unsustainable groundwater development, reduce enforcement costs, better account for cultural diversity in transboundary aquifer management and increase community resilience to changes in regional climate. Although we focus on groundwater, our methods and findings apply broadly to other resource management issues.Global groundwater resources are threatened by over-extraction. An agent-based model is presented, incorporating cooperative and collective action theory that reveals tipping points in social attitudes toward conservation in three at-risk regions.

Groundwater Resource Assessment and Conceptualization in the Pilbara Region, Western Australia

The Pilbara region is one of the most important mining hubs in Australia. It is also a region characterised by an extreme climate, featuring environmental assets of national significance, and considered a valued land by indigenous people. Given the arid conditions, surface water is scarce, shows large variability, and is an unreliable source of water for drinking and industrial/mining purposes. In such conditions, groundwater has become a strategic resource in the Pilbara region. To date, however, an integrated regional characterization and conceptualization of the occurrence of groundwater resources in this region were missing. This article addresses this gap by integrating disperse knowledge, collating available data on aquifer properties, by reviewing groundwater systems (aquifer types) present in the region and identifying their potential, and proposing conceptualizations for the occurrence and functioning of the groundwater systems identified. Results show that aquifers across the Pilbara Region vary substantially and can be classified in seven main types: coastal alluvial systems, concealed channel iron deposits, inland valley-fill aquifers, karstified dolomites, sandstone aquifers (West Canning Basin), Permian/Cenozoic Paleochannels, and Fractured Rock aquifers. Coastal alluvial systems show the greatest regional potential as water sources and are currently intensively utilised. Conceptually, the main recharge processes are infiltration of precipitation associated with cyclonic events and the interaction with streamflows during summer season, whereas the main discharge mechanisms correspond to evapotranspiration from riverine and coastal vegetation, discharge into the Indian Ocean, and dewatering of iron-ore bodies to facilitate mining activities. Important gaps in the knowledge relate to aquifer connectivity and accurate quantification of recharge/discharge mechanisms.

Implementation of the IPCC SRES Scenario A1B with the Land Use Modelling Platform contribution to the JRC PESETA II project

The Land Use Modelling Platform (LUMP) has been chosen to simulate land-use changes under a subset of scenarios (A1B). The modular structure of this platform, together with its high spatial resolution (100m), makes LUMP a suitable tool in the context of PESETAII. First, it guarantees high flexibility in adapting to the input/output interface required by the macro-economic models developed within this project. Moreover, an important added value to the modelling chain of PESETAII is the capability of taking into account specific policies with spatial repercussions.