Global Environmental Change AltersBreeding TargetsCertain aspects of global environmental changeare beneficial to agriculture. Rising CO2acts as afertilizer for C3 crops and is estimated to accountfor approximately 0.3% of the observed 1% rise inglobal wheat production (4), although this benefitis likely to diminish, because rising temperatureswill increase photorespiration and nighttime res-piration. A benefit of rising temperatures is thealleviation of low-temperature inhibition of growth,which is a widespread limitation at higher latitudesand altitudes. Offsetting these benefits, however,are obvious deleterious changes, such as an in-creased frequency of damaging high-temperatureevents, new pest and disease pressures, and al-tered patterns of drought. Negative effects of otherpollutants, notably ozone, will also reduce benefitsto plant growth from rising CO2and temperature.Particularly challenging for society will bechanges in weather patterns that will requirealterations in farming practices and infrastructure;for example, water storage and transport networks.Because one-third of the world’sfoodisproducedon irrigated land (5,6), the likely impacts onglobal food production are many. Along withagronomic- and management-based approaches toimproving food production, improvements in acrop’s ability to maintain yields with lower watersupply and quality will be critical. Put simply, weneed to increase the tolerance of crops to droughtand salinity.In the context of global environmental change,the efficiency of nitrogen use has also emerged asa key target. Human activity has already morethan doubled the amount of atmospheric N2fixe