Climate change refers to changes in temperature, rainfall and weather conditions over a long period of time. Factors that causes Climate change include; pollution, deforestation and other human activities.
When climate changes it results to variation in temperature either to extreme high or extreme low and variation in weather conditions which often affect agriculture positively or negatively.
Though majority of it, is negative effects. We talk of positive impacts because there are some crops whose yields are high at high temperatures (Cereal crops).
Rising temperatures and changes in weather conditions often lead to low yields due to water scarcity caused by heat waves and drought.
Livestock is also affected by climate change as increase in temperature reduces availability of pasture that is used as animal feed .
Climate change is very likely to affect food security at the global, regional, and local level. Climate change can disrupt food availability, reduce access to food, and affect food quality.For example, projected increases in temperatures, changes in precipitation patterns, changes in extreme weather events, and reductions in water availability may all result in reduced agricultural productivity.
Increases in the frequency and severity extreme weather events can also interrupt food delivery, and resulting spikes in food prices after extreme events are expected to be more frequent in the future. Increasing temperatures can contribute to spoilage and contamination.
Climate change Impacts
Warmer temperatures over time are changing weather patterns and disrupting the usual balance of nature. This poses many risks to human beings and all other forms of life on Earth.
Hotter temperatures
Nearly all land areas are seeing more hot days and heat waves; 2020 was one of the hottest years on record. Higher temperatures increase heat-related illnesses and can make it more difficult to work and move around. Wildfires start more easily and spread more rapidly when conditions are hotter.
The impacts of climate change on different sectors of society are interrelated. Drought can harm food production and human health. Flooding can lead to disease spread and damages to ecosystems and infrastructure.
Human health issues can increase mortality, impact food availability, and limit worker productivity. Climate change impacts are seen throughout every aspect of the world we live in. However, climate change impacts are uneven across the country and the world — even within a single community, climate change impacts can differ between neighborhoods or individuals.
Long-standing socioeconomic inequities can make underserved groups, who often have the highest exposure to hazards and the fewest resources to respond, more vulnerable.
Global temperatures rose about 1.98°Foffsite link (1.1°C) from 1901 to 2020, but climate change refers to more than an increase in temperature. It also includes sea level rise, changes in weather patterns like drought and flooding, and much more.
Things that we depend upon and value — water, energy, transportation, wildlife, agriculture, ecosystems, and human health — are experiencing the effects of a changing climate.
Climate Change Effects On Agriculture Crop 
Agriculture and fisheries are highly dependent on the climate. Increases in temperature and carbon dioxide (CO2) can increase some crop yields in some places. But to realize these benefits, nutrient levels, soil moisture, water availability, and other conditions must also be met.
1; Agriculture Economy
Agriculture contributed more than $1.1 trillion to the U.S. gross domestic product in 2019. The sector accounts for 10.9 percent of total U.S. employment—more than 22 million jobs.
These include not only on-farm jobs, but also jobs in food service and other related industries. Food service makes up the largest share of these jobs at 14 million.
Cattle, corn, dairy products, and soybeans are The United States is also a key exporter of soybeans, other plant products, tree nuts, animal feeds, beef, and veal.
2. Health Challenges to Agricultural Workers and Livestock
Agricultural workers face several climate-related health risks. These include exposures to heat and other extreme weather, more pesticide exposure due to expanded pest presence, disease-carrying pests like mosquitos and ticks, and degraded air quality.
Language barriers, lack of health care access, and other factors can compound these risks. Heat and humidity can also affect the health and productivity of animals raised for meat, milk, and eggs.
3. Impacts On Soil
When coupled with warming water temperatures brought on by climate change, runoff can lead to depleted oxygen levels in water bodies.
This is known as hypoxia. Hypoxia can kill fish and shellfish. It can also affect their ability to find food and habitat, which in turn could harm the coastal societies and economies that depend on those ecosystems.
Sea level rise and storms also pose threats to coastal agricultural communities. These threats include erosion, agricultural land losses, and saltwater intrusion, which can contaminate water supplies. Climate change is expected to worsen .
4. Changes in Agricultural Productivity
Climate change can make conditions better or worse for growing crops in different regions. For example, changes in temperature, rainfall, and frost-free days are leading to longer growing seasons in almost every state.
A longer growing season can have both positive and negative impacts for raising food. Some farmers may be able to plant longer-maturing crops or more crop cycles altogether, while others may need to provide more irrigation over a longer, hotter growing season. Air pollution may also damage crops, plants, and forests.
For example, when plants absorb large amounts of ground-level ozone, they experience reduced photosynthesis, slower growth, and higher sensitivity to disease
Pests and Diseases Caused By climate Change On Agriculture Crops
Pest and disease symptoms can vary greatly. Symptom expression for your particular crop may not match those demonstrated here. Consult your local extension agent for further assistance. For additional crop disease information, contact the University of Minnesota Crop Disease Clinic at: 612-625-1275.
Additional background information on insect damage, types of plant diseases, preventing problems, and specific pest management methods can be found in the Midwest Vegetable Pest Management Guide or the Midwest Fruit Pest Management Guide.
Insects
Many types of insects have the potential to damage fruit and vegetable crops. Various grasshoppers, weevils, beetles, and small insects like thrips and certain fly larva can cause significant damage.
Among the most common types of detrimental insects are the Lepidoptera (moths and butterflies), and the Homoptera (aphids and leafhoppers).
Damage caused by moth larvae often consists of ragged chewed leaf edges or holes in leaves. Homopteran insects like aphids are often difficult to see without a magnifying lens but their damage can be recognized by yellow speckles accompanied by a sticky film on leaf surfaces.
Other insects cause various types of damage including defoliation, or stem and fruit tunnelling. When investigating insect damage look for weak or stunted plants with damaged leaves or fruit.
Check the base of the plant near the ground and check the undersides of leaves for insects and insect eggs. Often the best time to spot insects in the process of feeding is at dusk, or in the early morning.
Many insects are beneficial, either for crop pollination, or as predators of nuisance insects. Never use pesticides on an insect you cannot identify, and only use pesticides labelled for that insect.
Diseases
Plant diseases are broadly classified as "Biotic" or "Abiotic." Biotic diseases are those caused by living organisms, like fungi, bacteria, and even viruses.
Biotic diseases usually appear on random plants throughout a field and effect different plants with different levels of severity. Often plants have visible signs of disease-like fluffy masses of mold. In general, fungal diseases can often be recognized by visible mold, orange pustules, and round leaf spots.
Bacterial diseases are often characterized by wet, or "watersoaked," lesions, or by irregular shaped leaf spots. Viruses often cause irregular color changes like mosaic patterns on leaves, or unusual foliage colors like red leaves. Nematodes, a microscopic worm are also classified as a biotic disease. They often cause root rots, or irregular root growth.
What Can We Do To Stop Climate Change
individuals to fight against climate change include;
- The use of varieties of species that can resist heat, drought and flooding.
- Building of water storage.
- Changing of agricultural calendar.
- Protect and prevent wildlife animals to allow species to migrate as climate changes.
Mitigation refers to strategies implemented to change an existing condition in order to improve productivity. Strategies used to mitigate climate change include;
1. Agronomical practices such as farming across the slopes to prevent erosion
2. The use of fertilizers to increase soil fertility.
3. Planting of trees that can help moderate the temperature.
Conclusion
Climate change poses a growing threat to sustainable development. The expected effects of climate change could seriously compromise the ability of the agriculture sectors to feed the world, and severely undermine progress toward eradicating hunger, malnutrition and poverty.