CARE2022 Hong Kong Conference

61 IV: Tertiary Unknown Risks It is crucial to understand vulnerabilities and exposure to climate related events to better prepare for them. While primary risks are predictable, secondary risks are more challenging, and tertiary risks can be total surprises. Primary risks are the direct physical impacts of a changing climate, such as rising temperature, heavier rainfall, stronger winds etc., which are predictable by models. Secondary risks are the known indirect impacts of climate change, such as food security, water security, and health issues. Tertiary risks are the indirect and unpredictable consequences of climate change that are difficult to prepare for, as an example, the increase of large-scale intense wildfires that have happened 5 Preparedness and Resilience in some parts of the world, such as California and Australia, when high temperatures dried the land, increasing the thermal contrast which led to strong winds, amplifying the intensity of wildfires. Such climate risks are highly non-linear and difficult to predict. Another example is the increase in potholes on asphalt roadways, such as in many parts of the United States, caused by changes in the freeze-thaw cycle associated with changes in subsurface temperatures. Resilience can be strengthened by learning from examples worldwide even if those incidents have not happened before in one’s own region because tertiary risks represent the unknown unknowns. An example illustrates what this means: FIGURE 5.28 Community program of Red Cross for high risk population in Hong Kong Source: Hong Kong Red Cross Disaster Preparedness Workshop, Drill and Equipment (Pok Fu Lam, Tai O, Cha Kwo Ling, Sai Kung)