Jumat, 21 Oktober 2011

Population growth

After decades of accelerating growth the global rate of population increase peaked at just over 2% a year during the late 1960s, and gradual declines of fertilities also speeded up the arrival of the absolute peak, at about 86 million people a year, during the latter half of the 1980s and the annual increase was down to 77 million people by the year 2000 (UN, 1998, 2001). As a result population projections issued during the 1990s had repeatedly lowered the long-term global forecasts for the next 50 years. The medium version of the 1998 revision envisaged just 8.9 billion people by the year 2050, down from 9.4 billion forecast in 1996, and 9.8 billion in the 1994 revisions (UN, 1998). And the high variant in 1998 was well below 12 billion people by the year 2050, in line with increasing indications that yet another doubling of human population to 12 billion people is unlikely (Lutzet al., 2001).
11                                                                                                 High
10                                                                                                 Medium
8                                                                                                   Low
1950 2000 2050
Figure 3.5
The UN’s latest long-term projections of global population growth (UN, 2001).

But the latest UN (2001) projection raised its medium 2050 forecast to 9.3 billion (Fig. 3.5). The difference of some 400 million people above the 1998 forecast is explained largely by the assumption of somewhat higher fertilities for the 16 develop-ing countries whose fertility has not, so far, shown any sustained decline. There is a different kind of uncertainty concerning the rich world’s population. Without substan-tial immigration it would start declining as a whole within a few years and by the year 2050 it would be barely above one billion, 20% below its current total (as already noted, UNO’s and FAO’s definitions of developed and developing populations are not identical: they differ by about 100 million people). With continued immigration it would be more or less stable, reaching 1.8 billion in 50 years. Even then many European nations and Japan would experience substantial population declines. Russia’s case is particularly noteworthy, as it now appears that there is little chance of revers-ing its population decline brought on by economic deprivation, social disintegration and exceptionally high rates of alcoholism. As a result, Russia may have 30 million fewer people by the year 2050. By that time the US population will, most likely, approach 340 million.
Inherent uncertainties of long-range forecasting aside, there is no doubt that virtu-ally all the net population increase of the next two generations will take place in today’s developing world, and that the global population of 2050 will, most likely, be 50% larger than it is today. Moreover, most of the additional population growth of some 2.8–3.2 billion people will be concentrated in nations whose agricultural resources, although absolutely large, are already relatively limited. Brazil is the only modernizing populous country (i.e., with more than 100 million people) with abundant reserves of arable land and water (Fig. 3.6). Fifty years from now India, after adding nearly 600 million people, would have a population more than 50% larger than today and would be, with just over 1.5 billion, the world’s most populous country, with China a very close second. Three African and two Asian countries would add more than 100 million people each: Nigeria, Pakistan, Indonesia, Congo, and Ethiopia. As a group these nations would have to increase their food harvests by two-thirds merely to maintain their existing, and in many respects inadequate, diets.
0.3                         Brazil
            Bangladesh China
0 200 400 600 800 1000 1200
Population (million)
Figure 3.6
Brazil and Nigeria are the only two developing countries with considerable reserves of potentially arable land; in all other populous modernizing countries future increases of food output will have to come from further intensification of cropping. Plotted from data in FAO (2001).

Only Congo and Nigeria have relatively low population density per hectare of cul-tivated farmland and large untapped agricultural potential. At the same time, the late 20th-century record of these two countries makes it hard to imagine that they will be the ones to mobilize their resources effectively and to evolve a civil society deter-mined to bring widespread economic advances. China and Indonesia are already the paragons of highly intensive cropping, and India and Pakistan are close behind. But, some poorly informed and sensationalized judgments notwithstanding (Brown, 1995), there is more hope for China’s farming than is the case with perhaps any other large populous country (Smil, 1995). As already noted, China has about 50% more farmland than has been officially acknowledged (which means that its actual average yields are substantially lower than reported) and it has many opportunities for increas- ing the productivity of its cropping (Smil, 1999c). India’s situation, though undoubt-edly highly challenging, appears to be more hopeful than the Indonesian or Pakistani prospect. As for Ethiopia, natural aridity affects large parts of its territory and already limits its food production capacity.


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