The Environmental Food Crisis

but above this range (after 2050) may decrease (IPCC, 2007; Meehl et al ., 2007). Model projections suggest that although increased temperature and decreased soil moisture will act to reduce global crop yields by 2050, the direct fertilization ef- fect of rising carbon dioxide concentration (CO 2 ) will offset these losses. The CO 2 fertilization factors used in models to project future yields were derived from enclosure studies con- ducted about 20 years ago. Free-air concentration enrichment (FACE) technology has now facilitated large-scale trials of the major grain crops at elevated CO 2 levels under full open-air field conditions. In those trials, elevated CO 2 enhanced yield by about 50% less than in the enclosure studies. Hence, previ- ous projections of no impact or even a slight positive impact of increasing CO 2 on global agricultural production by 2030 and 2050 may be too optimistic (Long et al ., 2006). Current research results conclude that while crops would respond posi-

tively to elevated CO 2 in the absence of climate change, the as- sociated impacts of high temperatures, altered patterns of pre- cipitation, and possible increased frequency of extreme events such as droughts and floods, will likely combine to depress yields and increase production risks in many world regions (Tubiello and Fischer, 2006). Furthermore, projected changes in the frequency and sever- ity of extreme climate events are predicted to have more seri- ous consequences for food and food security than changes in projected mean temperatures and precipitation (IPCC, 2007). Also, regional differences will grow stronger with time (Parry et al ., 2005), with potentially large negative impacts in develop- ing regions but only small changes in developed regions (IPCC 2007; Slater et al . 2007). Developing countries are more vul- nerable because of the dominance of agriculture in their econ-

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