Climate hazards cause direct harm, then spread losses through food, water, health, culture and the economy.
Direct impacts occur when a hazard affects people or property. Heat waves cause illness and reduce safe outdoor working time. Floods and cyclones can injure people, damage homes and interrupt transport or power. Drought reduces water supplies; wildfire brings flames and smoke. Evidence is needed to identify climate change's contribution to any single event.
Indirect impacts spread through connected systems. Damaged crops or fisheries reduce food and income, which are provisioning services. Flooded transport routes can stop deliveries even where farms remain productive. Prices may then rise far from the original hazard.
Changes in regulating services can affect health. Temperature and water conditions influence where disease vectors survive. Floods can disrupt sanitation and contaminate water. Health services, housing, vector control and behaviour also shape the outcome, so warming does not increase every disease everywhere.
Climate change can damage cultural services too. Declining Arctic sea ice affects traditional travel, practices and relationships with places for some Indigenous communities. Changes to reefs, glaciers and other valued landscapes affect recreation, tourism, heritage and identity. Their value extends beyond a market price.
People experience unequal losses because hazards, exposure and the ability to cope vary. Income, health, livelihoods, infrastructure and public support all matter. A flood may destroy a poorer household's only tools while an insured household can replace its possessions. The first loss can trigger further losses: less income means less money for food, healthcare and recovery. This is an impact cascade.
Step by step
Direct harm
Heat, floods, drought or storms affect exposed people and places.
Connected losses
Damaged ecosystems, services and transport affect livelihoods and supplies elsewhere.
Unequal recovery
Income, health, infrastructure and support affect who can cope and recover.
Worked example: Same heat, unequal effects
Two neighbourhoods experience similar hot weather. Residents with shade, reliable cooling and flexible work can reduce exposure. Outdoor workers with limited rest opportunities and older residents without cooling may face greater harm. The temperature alone does not determine the outcome.
Watch out for this
A place without the original hazard cannot experience a climate impact.
Food markets, transport, migration and other connections can transmit impacts between places.
Check your understanding
Drought reduces harvests abroad and raises food costs in an importing city. How is the city affected?
- Only through a direct local drought impact.
- Indirectly through a provisioning service and connected markets.
- It cannot be affected because the drought is overseas.