| It seems obvious that any significant change in | | | | is a player in both worlds: it is very much dependent |
| climate on a global scale should impact local | | | | upon environmental variables and is in turn an |
| agriculture, and therefore affect the world's food | | | | important agent of environmental change and a |
| supply. Considerable study has gone into questions of | | | | determinant of market prices. Climate change |
| just how farming might be affected in different | | | | presents crop production with prospects for both |
| regions, and by how much; and whether the net | | | | benefits and drawbacks. |
| result may be harmful or beneficial, and to whom. | | | | To address any of them more clearly we must first |
| Several uncertainties limit the accuracy of current | | | | define the main interactions that link a chain of |
| projections. One relates to the degree of | | | | processes together: food is derived from crops (or |
| temperature increase and its geographic distribution. | | | | from animals that consume crops); crops in turn grow |
| Another pertains to the concomitant changes likely to | | | | in fields, which exist in farms, which are components |
| occur in the precipitation patterns that determine the | | | | of farming communities, which are sectors in nation |
| water supply to crops, and to the evaporative | | | | states, and which ultimately take part in the |
| demand imposed on crops by the warmer climate. | | | | international food trade system. Understanding the |
| There is a further uncertainty regarding the | | | | potential impacts of global environmental change on |
| physiological response of crops to enriched carbon | | | | this sequence of interlocking elements is a first step |
| dioxide in the atmosphere. The problem of predicting | | | | in modeling what will happen when any one of them |
| the future course of agriculture in a changing world is | | | | is changed as a result of possible global warming, and |
| compounded by the fundamental complexity of | | | | a prerequisite for defining appropriate societal |
| natural agricultural systems, and of the socioeconomic | | | | responses. |
| systems governing world food supply and demand. | | | | In this summary we look first at the possible |
| What happens to the agricultural economy in a given | | | | biophysical responses of agro ecosystems to the |
| region, or country, will depend on the interplay of the | | | | specific environmental changes that are anticipated as |
| set of dynamic factors specific to each area. | | | | a result of the buildup of global greenhouse gases, |
| Scientific studies, typically based on computer models, | | | | and then at the range of adaptive actions that might |
| have for some time examined the effects of | | | | be taken to ameliorate their effects. In subsequent |
| postulated climate and atmospheric carbon dioxide | | | | sections we draw on our own and other modeling |
| changes on specific agro ecosystems--a now | | | | studies to show examples of regional and global |
| common term that defines the interactive unit made | | | | assessments that have so far been made, including |
| up of a crop community, such as a field of wheat or | | | | discussions of the effects of uncertainty, thresholds, |
| corn, and its biophysical environment. We have more | | | | and surprises, and the possible consequences of |
| recently gone a step farther by developing methods | | | | global warming on agricultural sustainability and food |
| to study these systems in more integrated regional | | | | security. Finally we give our own views on two |
| and global contexts. Both biophysical and | | | | potentially misleading notions regarding climate change |
| socioeconomic processes are taken into account in | | | | and agriculture. |
| these integrated studies, since agricultural production | | | | |