Environmental and Natural Resource Economics 3rd ed. Jonathan M Environmental and Natural Resource Economics 3rd ed. Jonathan M. Harris and Brian Roach Chapter 9 – Population and the Environment Copyright © 2013 Jonathan M. Harris

Figure 9.1: Global Population Growth and Projections, 1750-2100 Rapid global population growth is a phenomenon of the period since 1990. Prior to that population growth was slow, and only after 1950 did rates accelerate to as much as 2% a year. In recent decades rates of growth have slowed, but projected population increases in the developing world are still large. Sources: Caldwell and Schindlmayr, 2002; United Nations, 2010.

Figure 9.2: Net Annual Increase in Population by Decade, 1750-2100 The estimated net annual increase in population per decade shows a substantial expected continuing population increase through 2050 (based on U.N. median projections) although net change in the developed regions is projected to reach zero and then become slightly negative around 2030. Sources: Repetto, 1991; United Nations, 2010.

Table 9.1: Global Population Growth Rates and Average Gross Annual Increase 1.80 2.00 1.90 1.40 1.20 Average annual increase (millions) 50.6 65.7 75.6 85.3 81.6 76.5 Global population growth rates have been steadily declining since the 1960’s, but because the overall global population has grown, the average annual increase has remained high in absolute numbers – about the equivalent of the entire population of France each year. Source: United Nations, 2010.

Figure 9.3: World Population Growth Rate, 1950-2010, with Projections to 2050 The steady decline in population growth rates is projected to continue through 2050. (The dip in rates around 1959-60 reflects an increase in famine deaths in China.) Although this trend seem to indicate that global population is stabilizing, the net annual increase figures indicate that stabilization (a population growth rate of zero) is still decades away. Source: United States International Census Bureau, www.census.gov/population/international/data/idb/informationGateway.php.

2050 population projections (millions) 2010 Population (millions) Table 9.2: Population Projects for Three Fertility Scenarios   2050 population projections (millions) Regions 2010 Population (millions) Low fertility Medium fertility High fertility Africa 1,022 1,932 2,192 2,470 Asia 4,164 4,458 5,142 5,898 Latin America and Caribbean 590 646 751 869 Europe 738 632 719 814 Northern America 345 396 447 501 Oceania 37 49 55 62 More developed regions 1,236 1,158 1,312 1,478 Less developed regions 5,660 6,955 7,994 9,136 World 6,896 8,112 9,306 10,614 The most recent U.N. population projections show substantial growth by 2050, even in the low-range projection. Most analysts feel that the high-range projection of over 10 billion is unlikely, but the medium-range projection of over 9 billion has actually increased slightly over the 2005 projection. The medium-range projection represents a net addition of more than 2 billion people above the 2010 level. Source: United Nations, 2010.

Figure 9.4: Population Projections Through 2100, with Three Fertility Scenarios The shape of the three different population paths – high, medium, and low – shows the important role of population momentum. In the medium variant, population stabilizes in the second half of the twenty-first century, but in the low variant it starts to decline after about 2040, with significant overall decline by 2100. In the high variant, no stabilization is seen and population continues to grow through 2100, exceeding 14 billion. The difference between these drastically different paths is largely based on assumptions about fertility rates. Sources: United Nations, 2010. Notes: Future population growth is highly dependent on the path that future fertility takes. The United Nations uses three scenarios or “variants” for the future evolution of fertility: • Medium variant: assumes that world average fertility will decline from 2.52 children per woman in 2005–2010 to 2.17 children per woman in 2045–2050. • High variant: assumes that fertility levels will remain about half a child above the levels projected in the medium variant, i.e., will reach 2.64 children per woman in 2045–2050. In this scenario, world population would reach 10.6 billion by 2050 and 15.8 billion by 2100. • Low variant: assumes that world average fertility will drop to a level of about half a child below the medium variant, i.e., to 1.71 children per woman in 2045–2050. In this scenario, world population peaks at mid-century at about 8.1 billion, then decreases to 6.2 billion by the end of the century.

Figure 9.5: Projected Population Age Structure for “Equatoria” Current Population Age Structure for “Equatoria” Age Over 50 25-30 Under 25 1M 2M 4M Projected Population Age Structure for “Equatoria” Total Population 2025 10M Total Population 2000 7M Total Population 2050 12M The population age structure in this hypothetical country is actually not very different from actual patterns observed in much of Africa and some parts of Asia. It essentially guarantees continued population growth –close to a doubling – even with an immediate fall to replacement fertility.

Figure 9.6: Population Age Structures for Sub-Saharan Africa and Western Europe, 1990 The actual population age structure for Sub-Saharan Africa is even more dramatic than the previous hypothetical example. (Visualize what will happen to the pyramid as the current large generation of children become parents, then grandparents, and the older generations die). At the other extreme, the Western European pattern shows a complete stabilization of population and the beginnings of a decline, with a smaller generation of children than parents. Source: U.S. Census Bureau, International Data Base, 2011, www.census.gov/population/international/data/idb/informationGateway.php.

Figure 9.7: Alternative Futures for World Population Low Variant High Variant Global population projections depend on assumptions about fertility. While overall population will certainly grow (shown by the darker areas of additional population in each age cohort in 2030), in the low variant the growth has nearly ended by 2030, and the younger generation is becoming a bit smaller by that date (shown by the lighter areas in the youngest cohorts). In the high variant, growth continues, with the generation of children in 2030 being the largest in world history, and a likely driver of further growth. Source: United Nations, 2010. Notes: Male population on left, female on right. In low variant, 2030 age groups 0–4 and 5–9 are smaller than comparable 1990 groups.

Figure 9.8: The Demographic Transition Birth/Death Rates Per 1,000 Population Stable: High Birth High Death Increasing Growth Rate Decreasing Low Birth Low Death 10 20 30 40 I II III IV Birth Death The classic pattern of demographic transition in based on the historical experience of Europe, which is now in Stage 4. The world as a whole is still in Stage 3, with a decreasing but still substantially positive growth rate (as shown by the difference between birth and death rates).

Figure 9.9: Total Fertility Rate vs. GDP per capia, 2009 Angola Jordan Saudi Arabia Niger Hong Kong United States France Japan Iraq Malaysia Chile Singapore World Bolivia Actual fertility patterns show a clear negative relationship to GDP/capita, with a “waterfall” effect of rapid decline up to an income of 10,000 per capita. But not all countries follow this pattern, and declining fertility may actually be related more closely to factors such as health care and the status of women than directly to GDP/capita. Source: World Bank, World Development Indicators, http://data.worldbank.org/data-catalog/world-development-indicators. Note: Countries with population over 5 million plotted. GDP = gross domestic product.

Table 9.3: Per-Person Ecological Footprint of Consumption, 2005 Country/Region Population (millions) Ecological footprint of consumption (gha* per person) Biocapacity (gha per person) Ecological deficit or reserve (gha per person) World 6,476 2.69 2.06 –0.63 High income 972 6.40 3.67 –2.71 Middle income 3,098 2.19 2.16 –0.03 Low Income 2,371 1.00 0.88 –0.12 The ecological footprint shows area required to support individual consumption. It indicates a deficit (consumption higher than ecological support capacity) for the world as a whole, and especially for high-income countries. This is primarily due to the ecological capacity required to absorb carbon emissions from consumption in high-income nations. Source: Ecological Footprint Atlas 2008, Global Footprint Network, Research and Standards Department. Note: Gha = global hectare (a measure of area = 10,000 square meters or 2.47 acres). A global hectare represents one hectare of global average productivity.

Table 9.4: Total Ecological Footprint of Consumption, 2005 Country/region Population (millions) Ecological footprint of consumption (gha*) Biocapacity (gha) Ecological deficit or reserve (gha) World 6,476 17,444 13,361 –4,083 High income 972 6,196 3,562 –2,634 Middle income 3,098 6,787 6685 –102 Low income 2,371 2,377 2,090 –287 Total ecological footprint indicates that high-income countries have a large ecological deficit, while middle and lower income countries are closer to ecological balance. Source: Ecological Footprint Atlas 2008, Global Footprint Network, Research and Standards Department. Note: Gha = global hectare (a measure of area = 10,000 square meters or 2.47 acres). A global hectare represents one hectare of global average productivity