Global disaster displacement risk The data currently available gives us information on past and current patterns of internal displacement associated with disasters, but it does not tell us enough about what to expect in the future. The fact that most disasters that could take place have not yet happened means that what we know about the associated scale and global distribution of displacement does not necessarily correspond to what it may be in the years and decades to come. The limitations we face in trying to gain insights into future displacement risk from interpreting historical data are overcome by modelling. Probabilistic risk assessments simulate future displacement events associated with disasters which are likely to occur. This is vital not only for framing global policy, but also for policymakers, budget holders and planners at the national level, who need to allocate scarce resources based on limited understanding of future trends and risk. Presently, IDMC’s modelled estimates provide the only global baseline of future displacement risk. How many people are at risk of being displaced? Where? How often, and as a result of which types of hazard? These are questions raised in the Sendai Framework for Disaster Risk Reduction 2015-2030 and the UNFCCC Paris Agreement. In order to begin answering these questions our updated model simulates displacement caused by large-scale and relatively infrequent hazards for which there is little or no recorded data. We assess prospective displacement risk by analysing the frequency and severity of hazards, and the number of people and homes exposed and vulnerable to them. Probabilistic risk models for disasters are normally used to present potential economic losses in the form of metrics such as average annual loss and probable maximum loss. In the case of displacement risk, the model shows us potential average numbers of people displaced annually over long periods of time, and the probable maximum displacement that might be expected within a given period of time. The latter can also be presented as the probability of at least a certain number of people being displaced for a given return period. This metric is particularly relevant for urban planners and settlement programmes in areas prone to hazards, which have to consider the expected lifespan of the built environment and the associated risks for those who inhabit it beyond a few decades. Modelled global average annual displacement associated with hazards such as earthquakes, tsunamis, riverine floods and tropical cyclones is almost 11 million. This number is significantly lower than IDMC’s reported figures because it is only based on housing destruction. Absolute numbers are concentrated in countries with a high density of settlements and populations in coastal areas, and on seismic fault lines and flood-prone river basins. In such areas, exposure tends to be the dominant driver of displacement risk (see figure 1.22). Figure 1.22: Countries with largest modelled Average Annual Displacement (absolute value) Source: IDMC, with UNISDR data [PEOPLE] ON THE GRID: Global internal displacement in 2016 45