Environmental and Natural Resource Economics 3rd ed. Jonathan M. Harris Updates for Third Edition Chapter 10: Population and Environment Copyright © 2012 Jonathan M. Harris

Figure 10.1 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 11950 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. Source: United Nations Department of Economic and Social Affairs of the United Nations Secretariat, Population Division, World Population Prospects: The 2010 Revision, http://esa.un.org/unpd/wpp/index.htm, Medium Variant; Caldwell and Schindlmayr, 2002.

Figure 10.2 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: United Nations 2010, Repetto, 1991.

Table 10.1 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. Sources: United Nations 2010

Figure 10.3 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 associated with Mao’s Great Leap Forward and natural disasters.) Although this trend seem to indicate that global population is stabilizing, the net annual increase figures indicate that stabilization is still decades away (next slide) Source: United States International Census Bureau, http://www.census.gov/population/international/data/idb/informationGateway.php

Table 10-2: 2050 Population Projections Under 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: Population Division of the Department of Economic and Social Affairs of the United Nations Secretariat, World Population Prospects: The 2010 Revision, http://esa.un.org/unpd/wpp/index.htm,Monday, July 18, 2011

Figure 10.4 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. Source: United Nations, G. Pison, Population and Societies, no. 482, INED, October 2011

Figure 10.5: Projected Population Age Structure for "Equatoria" 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 10.6: Population Age Structures for Sub-Saharan Africa & Western Europe 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. Western Europe Source: U.S. Census Bureau, International Data Base, 2011 at http://www.census.gov/population/international/data/idb/informationGateway.php

Figure 10.7: Alternative Futures for World Population Low 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. High variant Source: Population Division of the Department of Economic and Social Affairs of the United Nations Secretariat, World Population Prospects: The 2010 Revision, http://esa.un.org/unpd/wpp/unpp/panel_indicators.htm

Figure 10.8: The Demographic Transition 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 10.9 Total Fertility Rate vs. GDP per Capita, 2009. 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. Note: countries with over 5 million population plotted. Sources: CIA World Fact Book, Wikimedia commons

Table 10.3: 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 6476 2.69 2.06 -0.63 High Income 972 6.40 3.67 -2.71 Middle Income 3098 2.19 2.16 -0.03 Low Income 2371 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 especially due to the ecological capacity required to absorb carbon emissions from consumption in high-income nations. 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. Source: The Ecological Footprint Atlas 2008, Global Footprint Network, Research and Standards Department

Table 10.4: Total Ecological Footprint of Consumption, 2005 Country/Region Population [millions] Ecological Footprint of Consumption [gha*] Biocapacity [gha] Ecological Deficit or Reserve [gha] World 6476 17444 13361 -4083 High Income 972 6196 3562 -2634 Middle Income 3098 6787 6685 -102 Low Income 2371 2377 2090 -287 Total ecological footprint indicates that high-income countries are responsible for most of the planetary ecological deficit. 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. Source: The Ecological Footprint Atlas 2008, Global Footprint Network, Research and Standards Department