Explain how climate change can affect agriculture and forestry.

The overall effect of a warmer climate on agricultural productivity is difficult to predict because the effect will vary regionally. Productivity might increase in some areas and decrease in others. Some croplands already stressed by heat and water availability could be pushed beyond their ability to produce food. If average temperatures increase by more than a few where they have not been seen before, most tropical and subtropical areas will likely see decreased crop production, and farmlands in mid-latitudes may begin to see significant declines. Conversely, warmer temperatures could potentially lead to longer growing seasons and increase agricultural productivity at higher latitudes. In addition, temperate areas that begin to experience a more subtropical climate may see the invasion of more tropical crop pests into regions that have not experienced them before. Plants need warmth and carbon to grow. Forests may become more productive because additional carbon dioxide can act as a fertilizer. The frequency and intensity of drought and forest fires could increase. Forest communities could in general move northward and upward in elevation as temperature and moisture levels change. Finally, both agricultural and forest systems may experience changes in pollinator populations which could affect the abundance and distribution of many plant species.