The effects of climate change on crop and terrestrial food production are evident in several regions of the world. Climate trends are affecting the abundance and distribution of harvested aquatic species, both freshwater and marine, and aquaculture production systems in different parts of the world.
The chapter will discuss the following key messages:
- Studies have documented a large negative sensitivity of crop yields to extreme daytime temperatures around 30°C.
- Evidence since AR4 confirms the stimulatory effects of carbon dioxide (CO2) in most cases and the damaging effects of elevated tropospheric ozone (O3) on crop yields.
- Changes in climate and CO2 concentration will enhance the distribution and increase the competitiveness of agronomically important and invasive weeds.
All aspects of food security are potentially affected by climate change, including food access, utilization, and price stability.
- There remains limited quantitative understanding of how non-production elements of food security will be affected, and of the adaptation possibilities in these domains.
- For the major crops (wheat, rice, and maize) in tropical and temperate regions, climate change without adaptation will negatively impact production for local temperature increases of 2°C or more above late-20th-century levels, although individual locations may benefit Projected impacts vary across crops and regions and adaptation scenarios, with about 10% of projections for the period 2030–2049 showing yield gains of more than 10% and about 10% of projections showing yield losses of more than 25%, compared to the late 20th century.
- On average, agronomic adaptation improves yields by the equivalent of ~15-18% of current yields, but the effectiveness of adaptation is highly variable ranging from potential dis-benefits to negligible to very substantial.
- Global temperature increases of ~4°C or more above late-20th-century levels, combined with increasing food demand, would pose large risks to food security globally and regionally. Risks to food security are generally greater in low- latitude areas.
- Changes in temperature and precipitation, without considering effects of CO2, will contribute to increased global food prices by 2050, with estimated increases ranging from 3 to 84%.
- Adaptation in fisheries, aquaculture, and livestock production will potentially be strengthened by adoption of multi-level adaptive strategies to minimize negative impacts.
- A range of potential adaptation options exist across all food system activities, not just in food production, but benefits from potential innovations in food processing, packaging, transport, storage, and trade are insufficiently researched.