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  1. 1
    098826

    Sustaining life on the earth.

    Kates RW

    SCIENTIFIC AMERICAN. 1994 Oct; 114-22.

    At the time of the toolmaking revolution, around 1 million years ago, human numbers rose to 5 million. As humans invented agriculture and animal husbandry, the population grew to about 500 million. In 1994 the number was 5.6 billion; it may double or triple before leveling off again 300 years after the industrial revolution began. If the transition to a warmer, more crowded, more diverse world can be managed, there may be promise of an environmentally sustainable future. The reconstructed population series for 4 ancient regions, the Nile Valley (6000 years), the Tigris-Euphrates lowlands of Iraq (6000 years), the basin of Mexico (3000 years), and the central Maya lowlands of Mexico and Guatemala (2200 years) all show waves in which population doubled over the previous base and then fell by at least half. This raises questions about human life on the earth: perhaps even regions that are world leaders can collapse in modern times. Among likely threats are 3 areas of concern: 1) pollutants: acid rain in the atmosphere, heavy metals in the soils, and chemicals in the groundwater, 2) global atmospheric dangers of nuclear fallout, stratospheric ozone depletion, and climatic warming, 3) deforestation, desertification, and species extinction. 10 billion people would require a 4-fold increase in agricultural production, a 6-fold rise in energy use and an 8-fold increase in the global economy. 2.1 births per woman is required for zero-population growth, while the current birth rate is 3.2. In developing countries after World War II, the life expectancy at birth was 40 years, now it has increased to 65 years. The slowing of the rate of population growth everywhere is encouraging for sustaining life on the earth, which requires cohabitation with the natural world; limits to human activity; and wider distribution of the benefits of human activity.
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  2. 2
    075865

    Land use and management in PR China: problems and strategies.

    Cai Y

    LAND USE POLICY. 1990 Oct; 7(4):337-50.

    The conflict between population and land in China results from high population density, declining availability of arable land, decrease in cropland, overgrazing, inability to afford imported grain, and expansion of land use for urbanization. Unwise decisions have been made. These decisions have resulted in land degradation, soil erosion, deforestation, degradation of grasslands, waste of land for freight storage or waste disposal due to low grain prices, and nonagricultural constructions on croplands. Ineffective land management problems are identified as: 1) the lack of an economic means of guiding land use and land is not valued; the lack of any mechanism to ensure economic land use including public lands which are not accounted for with rent; 2) the lack of integration of departments into the decision making structure and too many departments making decisions about the same land; 3) the lack of choice in land use which results in higher government departments being unaware of local conditions, and the lack of appropriate investment which results in short-term exploitation; and 4) surveys are inadequate for decision making. The strategies suggested for improvement in land use management include low resources expenditure in production and appropriate goods consumption. The goal is to sustain subsistence with gradual improvement through development. Land resources must be conserved and the environment protected. The solutions to depend on food imports or reduce the nutritional level deny the equally plausible solution to generate a higher level of input. The profit motive and scientific agricultural practices could accomplish this end. Reclamation for cropland is possible for 8 million hectares of wasteland in wide areas in Sanjiang Plain and 3.4 million hectares in small pockets in Eastern Monsoon China. Traditional agriculture must be transformed and an optimum scale of land operation established. Land tenure reform is necessary. Regional conditions must prevail as the guiding principles. Several implementation strategies are suggested: controlling population growth and establishing a balance between expenditure and land productivity, expanding and conserving forest areas, increasing agricultural investment, reforming land tenure, adjusting land product prices, strengthening land administration, developing other industries, and reforming economic and political systems.
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