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