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

) will offset

these losses. The CO

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

levels under full open-air

field conditions. In those trials, elevated CO

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

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

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-