How does this relate to agriculture?
Warmer temperatures would likely result in a change of the ecosystem. Plants that once grew in certain regions will now thrive farther north. Soil moisture could decrease under the higher temperatures and more intermittant rainfall, even if the total amount of rainfall increases. The growing season could increase in length, leading to longer growing periods. Some crops could benefit from warmer temperatures and increased carbon dioxide while others might not. Crops that are already near their temperature limits will be the most affected in terms of yield and quality if temperatures continue to rise. The crops that are not near their temperature thresholds would benefit from warmer temperatures, and would likely increase their yield and quality. Freezes in Florida would be reduced, leading to decreased loss from cold weather, and citrus crops might be able to migrate north of their current range.
Because of the warmer temperature and potential drying of the soil, irrigation may need to be expanded, or else marginal lands will have to be taken out of production or switched to more suitable crops. Pests could increase in range, necessitating the use of more pesticides. Forests could also die back and change to a more open prairie.
All of these local changes will take place in the context of a world that is also changing in many ways. Economic demands, health issues, coastal changes, energy needs and production methods, and population growth will also be varying in ways that are difficult to predict now. All of these changes will affect the costs of agricultural production and the demand for your products in the future.