World agriculture towards 2030/2050: the 2012 revision - Fao

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PROOF COPY World irrigated areas are estimated to be some 300 million ha, more than twice the level of the early 1960s. This refers to the area equipped for irrigation, 80-90 percent of which is thought to be in use. The potential for further expansion of irrigation, however, is limited. There are plenty of renewable water resources globally; but they are extremely scarce in regions such as the Near East/North Africa, or Northern China, where they are most needed. It must also be noted that the very concept of irrigation potential for further expansion is not unambiguous: renewable water resources that are adequate for irrigating any given amount of land today may not be so in the future, as non-irrigation claims on water resources may reduce availability for irrigation. Moreover, potential impacts of climate change may alter precipitation and evapotranspiration patterns, hence affecting renewable water resources 8 . Likewise, irrigation based on non-renewable resources, e.g. using fossil water in desert irrigation schemes, is not counted in the irrigation potential. Subject to these provisos, it is estimated that globally there remain some 180 million ha in developing countries (no estimates are available for the developed countries) that offer possibilities for irrigation expansion, beyond the 235 million ha presently equipped in these countries. We project that 20 million ha of this reserve may be used by 2050 for net expansion in developing countries, making for total projected area of 253 million ha in these countries and a world total of 322 million ha, given that irrigated area in the developed countries should remain at around the present 68 million ha. This amount is in addition to whatever new irrigation is required to replace the part of existing irrigated areas that may be irremediably lost to degradation, water shortages, etc. By implication, in 2050 the remaining yet unexploited reserve in the developing countries will be less, probably much less, than 160 million ha if the global area equipped and usable for agriculture is to be 322 million ha in 2050. Gross investment in irrigation over the entire period to 2050 would need to be a multiple of that implied by the small net expansion, because existing irrigation schemes depreciate and need to be restored or replaced. Rough estimates of such investment requirements are given in Schmidhuber, Bruinsma and Bödeker (2011). Most of the world irrigated agriculture is today in developing countries. It accounts for some 40 percent of their harvested area under cereals but for some 60 percent of their cereals production. Nearly one half of the irrigated area of the developing countries is in India and China. One third of the projected increase will likely be in these two countries (Figure 1.8). 8 Renewable water resources of a given area are defined as the sum of the annual precipitation and net incoming flows (transfers through rivers from one area to another) minus evapotranspiration, runoff and groundwater recharge. 13
PROOF COPY Figure 1.8 Irrigated area, 2005/07 and 2050 (million ha) 140 120 100 80 60 40 20 0 68 Source: Chapter 4, Table 4.10. 1 7 127 2005/07 Increase to 2050 Developed India and China Other South & East Asia 4 51 The renewable water resources that would underpin the expansion of irrigation are extremely scarce in several countries. Irrigation water withdrawals from such resources are only 6.6 percent globally and even less in some regions. However, in the Near East/North Africa and in South Asia they already account for 52 percent and 40 percent respectively, in 2005-07; For some countries these percentages are higher, even though they are part of regions with overall plentiful resources, e.g. some countries of Central America and the Caribbean. Any country using more than 20 percent of its renewable resources for irrigation is considered as crossing the threshold of impending water scarcity. There are already 22 countries (developing but including some in the Central Asia region) that have crossed this threshold, 13 of them in the critical over 40 percent class. It is estimated that four countries (Libya, Saudi Arabia, Yemen and Egypt) use volumes of water for irrigation larger than their annual renewable resources. For these and many other countries the scope for maintaining irrigated production, let alone obtaining increases, depends crucially on exploiting whatever margins there exist for using irrigation water more efficiently 9 . This can provide some limited relief in the water scarce regions, particularly in the region that needs it most, the Near East/North Africa. Finally, concerning yields, as noted, they have been the mainstay of production increases in the past. For cereals, the world average yield was 1.44 tonnes/ha in the first half of the 1960s (average 1961-65), 2.4 tonnes/ha in the first half of the 1980s and is now 3.4 9 Water use efficiency in irrigation: the ratio between the crop water requirements and irrigation water withdrawals. Crop water requirements are estimated as consumptive water use in irrigation (deficit between potential crop evapotranspiration and precipitation minus runoff and groundwater recharge) plus water needed for land preparation (and weed control in the case of paddy rice). 3 31 Near East / North Africa 3 20 1 6 Latin America sub-Saharan Africa 14
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Page 3 and 4: Acknowledgements PROOF COPY This pa
Page 5 and 6: Boxes PROOF COPY Box 1.1 Measuring
Page 7 and 8: PROOF COPY Figure A.2.1.6 India: fo
Page 9 and 10: PROOF COPY producing countries rema
Page 11 and 12: PROOF COPY may fall from 2.3 billio
Page 13 and 14: PROOF COPY Minimum Dietary Energy R
Page 15 and 16: PROOF COPY Concerning the main prod
Page 17 and 18: PROOF COPY vegetable oil imports fo
Page 19: PROOF COPY constraints can be signi
Page 23 and 24: PROOF COPY Figure 1.9 World cereals
Page 25 and 26: PROOF COPY for both food and non-fo
Page 27 and 28: PROOF COPY 2050, reaching a peak of
Page 29 and 30: PROOF COPY 436 million in the over
Page 31 and 32: PROOF COPY CHAPTER 2 PROSPECTS FOR
Page 33 and 34: PROOF COPY Figure 2.1 kcal/person/d
Page 35 and 36: PROOF COPY The FAO estimates of und
Page 37 and 38: PROOF COPY by people. In particular
Page 39 and 40: PROOF COPY production potential. Th
Page 41 and 42: PROOF COPY Table: Growth in Populat
Page 43 and 44: PROOF COPY (Figure2.6), at 7.4 bill
Page 45 and 46: PROOF COPY Table 2.4 GDP assumption
Page 47 and 48: PROOF COPY Modest reductions in the
Page 49 and 50: PROOF COPY Such optimism notwithsta
Page 51 and 52: PROOF COPY in North Africa have hig
Page 53 and 54: PROOF COPY (which in our data appea
Page 55 and 56: PROOF COPY The other major commodit
Page 57 and 58: PROOF COPY Table 2.6 Changes in the
Page 59 and 60: PROOF COPY • Despite this slow pa
Page 61 and 62: PROOF COPY undernourishment and the
Page 63 and 64: PROOF COPY commodities and waste. F
Page 65 and 66: PROOF COPY Where does this leave us
Page 67 and 68: PROOF COPY Figure A.2.1.6 shows the
Page 69 and 70: PROOF COPY cereals for ethanol 41 .
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PROOF COPY consumption was heavily
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PROOF COPY Figure 3.2 Net agricultu
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PROOF COPY It is noted, however, th
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PROOF COPY Figure 3.4 Per capita fo
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PROOF COPY 2005/07. 45 Not all of t
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PROOF COPY Table 3.3 Net trade bala
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PROOF COPY growth in the ruminant s
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PROOF COPY Table 3.4 Meat: aggregat
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PROOF COPY countries in per capita
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PROOF COPY associated with such lar
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PROOF COPY Figure 3.8 World feed us
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PROOF COPY The production of biodie
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PROOF COPY the exports of the two m
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3.5 Roots, tubers and plantains 3.5
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PROOF COPY the two factors that mak
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PROOF COPY Net exports from develop
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PROOF COPY Figure 3.14 Sugar net tr
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PROOF COPY Climate change In evalua
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PROOF COPY Table 4.1 Increases in p
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PROOF COPY involved are considerabl
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PROOF COPY cropping intensities (6
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PROOF COPY No data exist on total h
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PROOF COPY Box 4.2 Agro-ecological
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PROOF COPY under cultivation. It is
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PROOF COPY products facing finite n
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PROOF COPY place in sub-Saharan Afr
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PROOF COPY The bulk of arable land
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PROOF COPY Figure 4.7 Area equipped
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PROOF COPY The developed countries
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PROOF COPY 4.2.5 Irrigation water r
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PROOF COPY harvested irrigated area
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PROOF COPY Figure 4.10 Annual growt
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PROOF COPY million ha at an average
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PROOF COPY producers 81 are about h
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PROOF COPY the often unfavourable a
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PROOF COPY Table 4.15 Fertilizer co
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PROOF COPY under way for some time,
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PROOF COPY Livestock production is
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Argentina Bolivia (Plurinational St
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Wheat Rice Maize Barley Millet Sorg
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PROOF COPY and yields by irrigated
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PROOF COPY References Alexandratos,
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PROOF COPY FAO (1996), Food, Agricu
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PROOF COPY Ma, Hengyun, Jikun Huang
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PROOF COPY van der Mensbrugghe, D.,
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