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