Climate change can impact livestock animals' food supply in multiple ways. First, the direct effects of temperature increase affect both fodder cultivation and productivity of rangelands, albeit in variable ways. On a global scale, there is confidence that with all else equal, every single 1 °C (1.8 °F) of warming would decrease the yields of the four most important crops by between ~3% for rice and soybean (a crop grown primarily for animal feed) and up to 6% and 7.4% for wheat and corn respectively. This global decline is dominated by negative impacts in already warm countries, since agriculture in cooler countries is expected to benefit from warming.However, this does not include the impact of changes in water availability, which can be far more important than the warming, whether for pasture species like alfalfa and tall fescue, or for crops. Some studies suggest that high water availability through irrigation "decouples" crops from climate as they become much less susceptible to extreme weather events, but the feasibility of this approach is obviously limited by the region's overall water security, especially once the warming reaches levels of 2 or 3 °C (3.6 or 5.4 °F).
Worldwide production of alfalfa, an important fodder plant
While climate change increases precipitation on average, regional changes are more variable, and variability alone adversely impacts "animal fertility, mortality, and herd recovery, reducing livestock keepers' resilience".:717 In Zimbabwe, uncertainty about rainfall under different climate change scenarios could mean the difference between 20% and 100% of farmers negatively affected by 2070, while the average livestock revenue could potentially increase by 6%, yet may also plunge by as much as 43%.
