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E11. The level of human population is a biological and ethical issue.


Student Outcome: E11.1

Explain how the growth of the human population is placing huge demands on the resources of the biosphere.




Despite humanity's success in feeding a growing world population, the natural resources on which life depends-fresh water, cropland, fisheries and forests-are increasingly depleted or strained. One hopeful sign for the new millennium is that population growth is slowing at a much faster rate than was previously predicted. While slowing, however, significant growth continues, meaning that more people will be sharing such finite resources as fresh water and cropland.


  • Population and Environment


Having reached nearly 6.1 billion in 2000, human population continues to grow. UN population projections for the year 2050 range from 7.9 billion to 10.9 billion, suggesting the extent to which we can influence our future. More people and higher incomes worldwide are multiplying humanity 's impact on the environment and on natural resources essential to life. Based on these trends, it is clear that the 21st century will witness even greater pressures on natural resources. Current demographic trends offer hope, however. Over the past 40 years the average number of children born to each woman has fallen from five to less than three. Young people increasingly want to wait to have children and to have smaller families. Policymakers have a choice. They can do nothing, or they can help ensure that in the 21st century the world 's population peaks with fewer than 8 billion people, simply by committing the financial resources to meet the needs of couples who want to have smaller families, later in life.


Go here to see the Earth Clock - has population information but plenty of other stuff.


  • Water


Currently, 434 million people face either water stress or scarcity. Depending on future rates of population growth, between 2.6 billion and 3.1 billion people may be living in either water-scarce or water-stressed conditions by 2025. For tens of millions of people in the Middle East and in much of Africa today, the lack of available fresh water is a chronic concern that is growing more acute and more widespread. The problem is worse than it often appears on the ground, because much of the fresh water now used in water-scarce regions comes from deep aquifers that are not being refreshed by the natural water cycle. In most of the countries where water shortage is severe and worsening, high rates of population growth exacerbate the declining availability of renewable fresh water. While 25 countries currently experience either water stress or scarcity, between 36 and 40 countries are projected to face similar conditions by 2025.


  • Cropland


The number of people living in countries where cultivated land is critically scarce is projected to increase to between 600 million and 986 million in 2025. Despite the Green Revolution and other technological advances, agriculture experts continue to debate how long crop yields will keep up with population growth. The food that feeds the future will be raised mostly on today 's cropland. The soil on this land must remain fertile to keep food production secure. The minimum amount of land needed to supply a vegetarian diet for one person without any use of artificial chemical inputs or loss of soil and soil nutrients is .07 hectares, or slightly less than a quarter of an acre. An estimated 415 million people already live today in countries that have less than that per person. Easing world hunger could become unimaginably difficult if population growth resembles demographers 'higher projections.


  • Fisheries


Most of the world 's ocean fisheries are already being fished to their maximum capacities or are in decline. Global fish production climbed modestly in 1997, the last year for which global data are available, almost entirely because the farming of fish expanded in the world 's most populous country, China. Most fisheries worldwide are fully exploited or in decline. While the number of individual fishers continues to increase, the amount of fish each one catches is falling steadily. The poor have long depended on fish for complete protein, but population growth is helping to push this important food source out of their reach.


  • Forests


Today over 1.8 billion people live in 36 countries with less than 0.1 hectare of forested land per capita, an indicator of critically low levels of forest cover. Based on the medium population projection and current deforestation trends, by 2025 the number of people living in forest-scarce countries could nearly double to 3 billion. Most of the world 's original forests have been lost to the expansion of human activities. In many parts of the developing world, the future availability of forest resources for food, fuel and shelter looks quite discouraging. Future declines in the per capita availability of forests, especially in developing countries, are likely to pose major challenges for both conservation and human well-being.


  • Climate


In 1998, the last year for which global data are available for both population and heat-trapping carbon dioxide emissions, per capita emissions of CO2 continued the upward trend that dominated the middle 1990s. When combined with growing world population, these increased per capita emissions accelerated the accumulation of greenhouse gases in the global atmosphere and, thus, future global warming. With 4.6 percent of the world 's population, the United States contributed close to 24 percent of all emissions from fossil fuel combustion and cement manufacture, by far the largest CO2 contributor among nations. Emissions remained grossly inequitable, with one fifth of the world 's population accounting for 62 percent of all emissions in 1996 while another-and much poorer-fifth accounted for less than 2 percent.


  • Biodiversity


More than 1.1 billion people live in areas that conservationists consider the most rich in non-human species and the most threatened by human activities. While these areas comprise about 12 percent of the planet's land surface, they hold nearly 20 percent of its human population. The population in these biodiversity hotspots is growing at a collective rate of 1.8 percent annually, compared to the world's population 's annual growth rate of 1.3 percent.


Source: http://www.populationaction.org/resources/factsheets/factsheet_13.htm


An interesting video showing how the populations of humans has changed since 1 A.D.

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Too much information?  Try this website which compares the world's population in 1950 to what it was in 2005 - and it does it visually!


Here is another, rather brash summary of population statistics. Turn your sound down.


Student Outcome: E11.2

Explain why the exponential growth of the human population is not sustainable.


  • Population growth over the last half-century is unparalleled in the history of our planet. Human population took hundreds of thousands of years to grow to 2.5 billion in 1950. Then in just 50 years, it more than doubled to exceed 6 billion. Most of this growth has been in developing countries where advances in public health have contributed to lower mortality at all ages. Until recently, death rates fell faster than birthrates, resulting in rapid population growth.


  • Many poor countries struggle to maintain health care, schooling and urban infrastructure in the face of rapid population growth. Disproportionately large populations of young people that result from this growth can strain governments. They also appear to make many developing countries more vulnerable to civil conflict, especially when combined with high rates of urban population growth and shortages of cropland. Economic evidence over the past few decades makes clear that as average family size shrinks, families can save more money, and this “demographic dividend” may help well-prepared governments direct available capital to domestic economic growth.


  • Per capita supplies of both renewable fresh water and cropland are falling as population grows. The United Nations Food and Agriculture Organization estimates that 852 million people worldwide were undernourished in 2000-2002, and the number of chronically hungry in developing countries increased at a rate of almost 4 million people a year in the second half of the 1990s. Continuing population growth also strains water resources. By 2025, between 2.75 billion and 3.25 billion people worldwide are projected to live in countries where water scarcity or stress threaten public health and constrain food production and economic development.


Source: http://www.populationaction.org/resources/factsheets/factsheet_7_7billion.htm


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