Climate change has a great impact on agriculture. This is both positive and negative.
Chop is from a presentation made by H.E president Uhuru Kenyatta.
Agriculture is among the sectors most directly exposed to climate variability and change, with consequences for food production and food security. A significant rise in mean temperature is likely to reduce crop yields in many areas, with the most threatened systems located in areas with decreasing rainfall. In cooler regions, more favourable mean temperatures and the extension of the growing season may stimulate potential productivity. More frequent dry spells in a warmer climate are likely to increase the risk of crop failure, unless irrigation can be expanded and be combined with improved water retention and water yield. In grasslands, the sensitivity may be larger in extensively than in intensively managed systems because of the lack of adaptive management interventions. Finally, climate change could seriously alter the productivity of animal systems, both through direct effects on the animal well-being and indirect effects via diet quality and forage availability. Overall, there is ample evidence that agricultural food systems are sensitive to climate change, and that effects on potential productivity ranges from being extremely negative in already water-limited areas to more favourable in currently temperature-limited regions.
For any particular crop, the effect of increased temperature will depend on the crop's optimal temperature for growth and reproduction. In some areas, warming may benefit the types of crops that are typically planted there, or allow farmers to shift to crops that are currently grown in warmer areas. Conversely, if the higher temperature exceeds a crop's optimum temperature, yields will decline.
Effect of climate change on agriculture:
1)Higher CO2 levels can affect crop yields. Some laboratory experiments suggest that elevated CO2 levels can increase plant growth. However, other factors, such as changing temperatures, ozone, and water and nutrient constraints, may counteract these potential increases in yield. For example, if temperature exceeds a crop's optimal level, if sufficient water and nutrients are not available, yield increases may be reduced or reversed. Elevated CO2 has been associated with reduced protein and nitrogen content in alfalfa and soybean plants, resulting in a loss of quality. Reduced grain and forage quality can reduce the ability of pasture and rangeland to support grazing livestock.
2)More extreme temperature and precipitation can prevent crops from growing. Extreme events, especially floods and droughts, can harm crops and reduce yields. For example, in 2010 and 2012, high nighttime temperatures affected corn yields across the U.S. Corn Belt, and premature budding due to a warm winter caused $220 million in losses of Michigan cherries in 2012.
3)Dealing with drought could become a challenge in areas where rising summer temperatures cause soils to become drier. Although increased irrigation might be possible in some places, in other places water supplies may also be reduced, leaving less water available for irrigation when more is needed.
4)Many weeds, pests, and fungi thrive under warmer temperatures, wetter climates, and increased CO2 levels.
5)The ranges and distribution of weeds and pests are likely to increase with climate change. This could cause new problems for farmers' crops previously unexposed to these species.
Though rising CO2 can stimulate plant growth, it also reduces the nutritional value of most food crops. Rising levels of atmospheric carbon dioxide reduce the concentrations of protein and essential minerals in most plant species, including wheat, soybeans, and rice. This direct effect of rising CO2 on the nutritional value of crops represents a potential threat to human health. Human health is also threatened by increased pesticide use due to increased pest pressures and reductions in the efficacy of pesticides
