6.3 What impacts have already been observed?
6.3.1 Regional variation in climatic change impacts on food production.
Impacts of climatic change on food production have varied between regions
Since the IPCC’s Fourth Assessment report in 2007 (AR4), impacts of climatic change have been noted across the planet, but with significant regional variation. There is no scope in this chapter to discuss all of these impacts in detail, but the sections that follow describe the complexity of relationships between environmental changes and outcomes for food systems.
6.3.2 Observed positive and negative impacts.
Some positive and negative impacts on crops have already been observed
The IPCC observed changes include:
- ‘medium confidence’ of negative impacts on wheat and maize yields in many regions (including major producing regions).
- small negative effect on yields for major producing regions of rice and soy.
- 'high confidence' that climatic change has benefited some crop yields in some high-latitude regions (e.g. North East China, UK).
- early flowering and maturing in some crops (e.g. apples, grapes).
- changes in the distribution of weeds and animal pests.
6.3.3 Impacts on terrestrial and aquatic livestock.
Migration of some fish species has been observed, while research on livestock has been limited
- Northern Atlantic: “high confidence” of a shift in population densities to northern ranges of habitats, away from southern ranges. This is associated with temperature increase.
- Ocean acidification – some negative impact on molluscs (i.e. their shells).
- Combined impact of overfishing and sea temperature changes, negatively impacting corals (and consequential impacts on marine ecosystems).
- It is difficult to separate the impacts of climatic change from those of over-fishing (see Chapter 5 for more on over-fishing).
- Very little research to date on impacts of climate change on livestock production.
- Heat stress for livestock is considered to be a risk, but little research has been undertaken.
- Water stress may also affect animal feed production.
- Impacts will depend not just on the region and animal type and breed, but also the type of livestock production system.