Weather condition prevailing over an area for a long period of time is known as climate. Crops grown in the United States are critical for the food supply livestock here and around the world.
U.S. farms supply nearly 25% of all grains (such as wheat, corn, and rice) on the global market. Changes in temperature, atmospheric carbon dioxide (CO2), and the frequency and intensity of extreme weather could have significant impacts on crop yields.
For any particular crop, the effect of increased temperature will depend on the crop’s optimal temperature for growth and reproduction.[1] 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. 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.
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.
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.
Many weeds, pests, and fungi thrive under warmer temperatures, wetter climates, and increased CO2 levels. Currently, U.S. farmers spend more than $11 billion per year to fight weeds, which compete with crops for light, water, and nutrients.
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.
- Impacts on Livestock
Americans consume more than 36 million metric tons of meat and poultry annually. Livestock and poultry account for over half of U.S. agricultural cash receipts, often over $100 billion per year. Changes in climate could affect animals both directly and indirectly.
Heat waves, which are projected to increase under climate change, could directly threaten livestock. In 2011, exposure to high temperature events caused over $1 billion in heat-related losses to agricultural producers.
Heat stress affects animals both directly and indirectly. Over time, heat stress can increase vulnerability to disease, reduce fertility, and reduce milk production.
Drought may threaten pasture and feed supplies. Drought reduces the amount of quality forage available to grazing livestock. Some areas could experience longer, more intense droughts, resulting from higher summer temperatures and reduced precipitation.
For animals that rely on grain, changes in crop production due to drought could also become a problem.Climate change may increase the prevalence of parasites and diseases that affect livestock.
The earlier onset of spring and warmer winters could allow some parasites and pathogens to survive more easily. In areas with increased rainfall, moisture-reliant pathogens could thrive.
Potential changes in veterinary practices, including an increase in the use of parasites and other animal health treatments, are likely to be adopted to maintain livestock health in response to climate-induced changes in pests, parasites, and microbes.
This could increase the risk of pesticides entering the food chain or lead to evolution of pesticide resistance, with subsequent implications for the safety, distribution, and consumption of livestock and aquaculture products.
Increases in carbon dioxide (CO2) may increase the productivity of pastures, but may also decrease their quality. Increases in atmospheric CO2 can increase the productivity of plants on which livestock feed.
However, the quality of some of the forage found in pasturelands decreases with higher CO2. As a result, cattle would need to eat more to get the same nutritional benefits.
Authors: Haroon Zaman khan, Muhammad Atif Shabbir, Noor Asif Ali, Muhammad Kashif Shabbir, Muhammad Farrukh Saleem and Ahmad Mukhtar.