3.4 3.b - Food-system shocks and Indigenous farming

Extreme weather and food-system shocks

A food-system shock is a disruption that changes production, distribution, access or use more rapidly than people and institutions can comfortably adjust.

Extreme heat can damage crops during sensitive growth stages and stress livestock or agricultural workers. Drought reduces soil moisture, pasture and water for processing. Floods can submerge crops, erode soil, contaminate stores and block roads. Wildfire can destroy vegetation, equipment and buildings, while smoke and disrupted work affect places beyond the burnt area. Timing matters: the same rainfall can support germination or ruin a harvest depending on when and how it occurs.

Climate change can alter the probability or intensity of these hazards, but the direction and magnitude vary by region and hazard. The IPCC's 2022 assessment identifies increasing risks to food systems from heat, drought, flooding and associated extremes. A single event's losses also depend on exposure, crop choice and adaptation, so they cannot be attributed to climate alone from its occurrence. IPCC AR6 Working Group II, technical summary.

El Niño is the warm phase of a coupled tropical Pacific ocean–atmosphere fluctuation, ENSO. It redistributes circulation and rainfall, producing different regional effects rather than drought everywhere. Some areas face reduced rainfall, others heavier rain, while marine changes can affect fisheries. ENSO is natural variability operating within a changing climate. The IPCC distinguishes uncertain changes in sea-surface-temperature variability from projected increases in ENSO-related rainfall variability; it is inaccurate to state simply that climate change makes El Niño occur more often. IPCC AR6 Working Group I, Chapter 4.

Water scarcity and agricultural production

Water scarcity occurs when accessible, suitable water is insufficient for demands, and it can be physical, economic or institutional.

A dry season can reduce river flow or reservoir storage just when irrigation demand rises. Groundwater pumping may buffer rainfall variability, but abstraction above recharge depletes the store and can raise pumping costs. A deeper water table can exclude farmers without powerful pumps before the aquifer is physically empty. Pollution or salinity can make water unsuitable even where a large volume exists.

Competition links sectors. Water allocated to cities, industry or ecosystem protection may reduce the amount available to agriculture; agricultural withdrawals can in turn affect drinking water and downstream habitats. A farmer may respond by changing crops, reducing irrigated area or investing in more efficient application. Efficiency on one field is not automatically a basin-wide saving if “saved” water is used to expand production or if return flows decline.

Effects spread beyond yields. Irrigation restrictions can reduce employment, processing throughput and export earnings, while higher prices affect households that buy food. Poorer farmers may have fewer options for storage, insurance or new equipment. The IPCC's water assessment identifies both the adaptation value and limits of irrigation and crop changes under increasing warming. IPCC AR6 Working Group II, Chapter 4.

Tectonic shocks to food systems

Tectonic hazards can interrupt food security through damaged land, lost assets and broken connections even when crops are not directly destroyed.

Earthquake shaking can collapse stores, damage irrigation and kill livestock; triggered landslides can bury fields or block roads. Tsunamis can erode coastal land, deposit debris and contaminate soils or freshwater with salt. Volcanic ash can damage vegetation, roofs and water systems, although long-term weathering of volcanic material can also contribute to soil fertility. Hazard type, deposit depth and recovery time must therefore be specified.