The ocean is emptying;
We have observed record setting harvests over the last few years, and yet chronic hunger persists and has recently been increasing;
The planet is experiencing the 6th great extinction;
All of these are the result of human activity.
This evidence illustrates that we have not responsibly managed, neither through governance nor technology, our environmental resources. In the absence of finding a sustainable relationship with our ecosystem, we might conclude that we have reached Earth's carrying capacity. This resource question often raises the contentious arguments first made famous by Malthus in the 19th century. His proposition that "the power of population is indefinitely greater than the power in the earth to produce subsistence for man," is the central theme of the debate. Obvious problems with this logic are conclusions justifying programs of population control, coercive reproductive health policies, eugenics, or that hunger deaths are economically and ecologically rational. Still, some view population stabilization as a necessary precondition for environmental sustainability and should be achieved without taking such excesses. Today, population policies include alleviating poverty, reducing child mortality, providing access to family planning, and encouraging female education.
Articles discussing Malthus and issues of demographics and carrying capacity have recently appeared. Also, a specific conversation regarding climate change and population has occurred involving the cost efficiency of family planning as a climate change mitigation tool. (A rebuttal to this population argument has been offered.) This post will overview the state of population and fertility as well as consumption per capita.
Population
By mid 2009, the world population reached 6.8 billion which puts the current rate at about 78 million people annually. If fertility levels decline in a predictable fashion, the world population is expected to reach 9.1 billion in 2050. This would be an increase of about 33 million people annually. (United Nations, 2009) These trends are demonstrated in Figures 1 and 2. Figure 1 shows population trajectories to 2050 given different fertility rates. Figure 2 demonstrates that population growth rates have reached an inflection point and are now declining.
High fertility is concentrated in few countries today due to major reductions in fertility since 1970. In 31 of the 49 least developed countries, fertility levels were above 5 children per woman around 2005. By 2005 women in the least developed countries had twice as many children on average as women in all the developing countries combined; about 4.8 vs. 2.4. (United Nations Development Program, 2009) Figure 3 shows a trajectory to a replacement fertility rate of 2.1 for a developed country. This replacement rate is when women reproduce just enough to replace themselves. The replacement rate is necessarily higher in areas with higher child mortality. Despite decreasing fertility, the planet will continue to observe an increase in population until mid-century.
Increased life expectancy has also contributed to population growth. Globally, life expectancy at birth is projected to rise from 68 years in 2005-2010 to 76 years in 2045-2050. In the developed countries, the projected increase is from 77 years in 2005-2010 to 83 years in 2045-2050, while in the less developed countries the increase is expected to be from 66 years currently to 74 years by mid-century. (United Nations, 2009) Figure 4 illustrates the large disparity in life expectancy between regions.
Associations among life expectancy, birth rate and income over time are demonstrated in the motion graph below. (See Figure 5) Low incomes, short life expectancy and high fertility rates are highly correlated. High incomes, long life expectancy and low fertility rates are also highly correlated.
Note: Scroll over a bubble to reveal which country it represents or click on the country in the right pane to graph it across time.
Additionally, economic and demographic changes will prompt international migration and alter population patterns. In annual averages, the main net receivers of migrants during 2010-2050 are projected to be the United States (1.1 million annually), Canada (214,000), the United Kingdom (174,000), Spain (170,000), Italy (159,000), Germany (110,000), Australia (100,000) and France (100,000). The main countries of net emigration are projected to be Mexico (-334,000), China (-309,000 annually), India (-253,000), the Philippines (-175,000), Pakistan (-161,000), Indonesia (-156,000) and Bangladesh (-148,000). (United Nations, 2009)
Consumption
Often times the discussion on the absolute number of people obscures actual resource consumption. It is important to explore consumption patterns since those regions with the lowest population growth have the highest levels of per capita consumption. Figures 6, 7 and 8 show per capita consumption patterns across emissions, meat and paper. These may be considered reasonable proxies for a complete picture of resource consumption
Although population stabilization may be viewed by some as a necessary condition for sustainable resource management, it may miss an important determinant of sustainability. The magnitude of resource consumption per capita in regions with very low or negative population growth is extremely high. Thinking of these two macro trends allows for a more balanced understanding of resource utilization.
Related Links
Demography, Growth and the Environment: Falling Fertility
The Global Food Crisis
What Stops Population Growth?
United Nations Press Release: World Population to Exceed 9 Billion by 2050
Highlights from the World Population Prospects, The 2008 Revision
What Would it Take to Accelerate Fertility Decline in the Least Developed Countries?
Atmospheric Carbon Dioxide - Mauna Loa
Impacts of Biodiversity Loss on Ocean Ecosystem Services
Fewer Emitters, Lower Emissions, Less Cost: Reducing Future Carbon Emissions by Investing in Family Planning
The Implications of Population Growth and Urbanization for Climate Change
EarthTrends
Population: Total population, both sexes
Population: Growth rate of total population
Demographics: Total fertility rate
Demographics: Life expectancy at birth, both sexes
CO2 Emissions: CO2 emissions per capita (source: WRI)
Meat Consumption: Per capita
Resource Consumption: Paper and paperboard consumption per capita
