Thus, it is important to at least point to some impending changes and speculate about their possible effects. One important factor is the continuing drive for higher agricultural productivity. As global population climbs, demand for farm products increases. Moreover, the economic survival of farms often depends on ever-higher output of products. At the same time, however, the higher yield targets may require more fertilizers and other inputs that could release more greenhouse gas.
Economic factors are another consideration.
As cost of inputs and price of products change, farmers alter their farming systems to maintain profits. Consequently, the area of land devoted to certain crops changes from year to year, which affects the release of greenhouse gases and other emissions. Perhaps the most dramatic example is the recent shift toward livestock-based systems. This change has far-reaching implications. On the one hand, higher livestock numbers usually mean more land in forages, which reduce atmospheric CO 2 by storing more C in soil.