The toll of natural hazards on essential services

Critical infrastructure, such as power lines, roads, and hospitals, provides essential services to society: access to power, mobility, or healthcare. An important feature of critical infrastructure is its interdependency – for example, healthcare and education services rely on power, road, and communication networks. When severe weather damages infrastructure assets, this dependency increases the risk of failure cascades, leading to disruption of essential services and everyday life. A unilateral focus on (insured) direct asset damages and an incomplete understanding of the scale and scope of such failure cascades limits our ability to prepare and adapt. Researchers at ETH Zurich and VU Amsterdam studied this aspect with a systemic risk modelling approach.

Disparities in service accessibility

The researchers found that physical destruction - a common risk indicator - is not a good proxy for service disruptions. In 2 out of 3 tropical cyclone events and in 6 out of 7 flood events, more people lose access to a service than those which are physically affected. While in rich, and densely built-up regions – such as Florida (US) or the UK – often the contrary is true, especially poor and rural regions – such as Madagascar or Mozambique – with few non-redundant roads, power lines or social infrastructure, service disruptions can spread by a factor of ten and more. Looking at it from the reverse end, service disruptions are majorly caused through infrastructure failure cascades, not through structural damage to individual infrastructure assets.

Enhancing climate-resilient infrastructure

Understanding the responses of interdependent infrastructure systems under stress helps to derive adaptation strategies for more climate-resilient services. Considering where people have (no) access to services, and why services are disrupted, by what type of weather event, can help prioritize between better protecting hazard-exposed key infrastructure assets, decentralizing and diversifying supporting infrastructures, or rather including hitherto left-out people into the system.