Risk depends on the hazard, the people or assets in its path, and how easily they can be harmed.
A hazard is an event or trend that could cause harm, such as a flood or rising sea level. Exposure means people, livelihoods, infrastructure or ecosystems are present where it can affect them. Vulnerability means they are susceptible to harm and have limited ability to cope or adapt. Together, these shape risk: possible losses of life, property or ecosystems.
Fast and slow hazards need different preparation. A cyclone or flash flood can strike over a short period. Sea-level rise and prolonged drought develop over longer periods. Rising seas can make a familiar coastal storm more damaging; repeated drought can exhaust savings and water reserves.
Location shapes exposure. Low coasts face rising seas and storm surges; dry areas face water scarcity. Building in floodplains increases exposure, while moving a facility away can reduce it. More valuable property in a hazard area can raise potential financial losses even when protection improves.
Vulnerability depends on housing, age, health, income, water, food reserves, healthcare and effective institutions. Warnings, accessible shelters and social support help people cope. A warning provides little protection if a resident cannot understand it or has no transport to leave.
Identify which part of risk a measure changes. Moving a facility out of a floodplain reduces exposure. Strengthening it reduces physical vulnerability. Neither stops the storm. Risk is not a universal numerical formula: the actual conditions matter.
Step by step
Hazard
What event or trend could cause harm, and where?
Exposure
Which people, assets or ecosystems lie within its reach?
Vulnerability
How easily could they be harmed, and what helps them cope?
Worked example: Two coastal settlements
Both settlements face the same storm surge. One has elevated housing, maintained shelters and accessible evacuation support; the other has fragile homes and limited transport. Hazard and exposure may be similar, while vulnerability and response capacity explain different risks.
Watch out for this
A wealthy place has no climate risk.
Wealth can fund protection, but high exposure, unequal access, infrastructure dependencies and extreme events can still produce large losses.
Check your understanding
Which action most directly reduces exposure to coastal flooding?
- Move a new hospital site to suitable land outside the flood-prone zone.
- Train staff to respond while keeping the hospital in the same place.
- Measure the storm more accurately but take no further action.