Rethinking Agriculture 10 - SPECIAL SECTION P ERSPECTIVE...

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PERSPECTIVE Radically Rethinking Agriculture for the 21st Century N. V. Fedoroff, 1 * D. S. Battisti, 2 R. N. Beachy, 3 P. J. M. Cooper, 4 D. A. Fischhoff, 5 C. N. Hodges, 6 V. C. Knauf, 7 D. Lobell, 8 B. J. Mazur, 9 D. Molden, 10 M. P. Reynolds, 11 P. C. Ronald, 12 M. W. Rosegrant, 13 P. A. Sanchez, 14 A. Vonshak, 15 J.-K. Zhu 16 Population growth, arable land and fresh water limits, and climate change have profound implications for the ability of agriculture to meet this century s demands for food, feed, fiber, and fuel while reducing the environmental impact of their production. Success depends on the acceptance and use of contemporary molecular techniques, as well as the increasing development of farming systems that use saline water and integrate nutrient flows. P opulation experts anticipate the addition of another roughly 3 billion people to the planet s population by the mid-21st centu- ry. However, the amount of arable land has not changed appreciably in more than half a century. It is unlikely to increase much in the future because we are losing it to urbanization, salin- ization, and desertification as fast as or faster than we are adding it ( 1 ). Water scarcity is already a critical concern in parts of the world ( 2 ). Climate change also has important impli- cations for agriculture. The European heat wave of 2003 killed some 30,000 to 50,000 people ( 3 ). The average temperature that summer was only about 3.5°C above the average for the last century. The 20 to 36% decrease in the yields of grains and fruits that summer drew little at- tention. But if the climate scientists are right, summers will be that hot on average by mid- century, and by 2090 much of the world will be experiencing summers hotter than the hottest summer now on record. The yields of our most important food, feed, and fiber crops decline precipitously at tem- peratures much above 30°C ( 4 ). Among other reasons, this is because photosynthesis has a temperature optimum in the range of 20° to 25°C for our major temperate crops, and plants develop faster as temperature increases, leaving less time to accumulate the carbohydrates, fats, and pro- teins that constitute the bulk of fruits and grains ( 5 ). Widespread adoption of more effective and sustainable agronomic practices can help buffer crops against warmer and drier environments ( 6 ), but it will be increasingly difficult to maintain, much less increase, yields of our current major crops as temperatures rise and drylands expand ( 7 ). Climate change will further affect agriculture as the sea level rises, submerging low-lying crop- land, and as glaciers melt, causing river systems to experience shorter and more intense seasonal flows, as well as more flooding ( 7 ). Recent reports on food security emphasize
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Rethinking Agriculture 10 - SPECIAL SECTION P ERSPECTIVE...

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