Introduction

In Chapter 6, we documented a broad albeit incomplete list of ways in which the earth has been transformed by human action. We are now in a geologic era named after us: The Anthropocene. The question as to whether or not there will be an official declaration of a geological era named the Anthropocene will be based on stratigraphic evidence preserved in the geological record. Has Homo sapiens left a distinctive signature in the rock, seafloor mud, and/or glacial ice that indicates a fundamental change in the planet? The Anthropocene Working Group (AWG) of the International Commission on Stratigraphy has voted to develop a proposal supporting the designation of the Anthropocene (Subramanian, 2019). Likely, radioactive isotopes associated with the nuclear age at the middle of the 20th century are likely the “golden spike” marking the onset of the Anthropocene era.

This time marks the start of the “Great Acceleration,” a vast transformation after the Second World War when the growing population began consuming resources and creating completely new materials at an exponential rate, eclipsing even the Industrial Revolution. All that activity poured unprecedented amounts of persistent organic pollutants into the environment, ramped up the rate of animal extinctions and created geological features that had never before existed. These include 4-kilometre-deep gold mines and landfills more than 70 metres high, such as Teufelsberg in Berlin, where rubble from the Second World War was piled into an artificial hill. Although the AWG is still exploring several potential golden spikes, the radioactive record from the nuclear age has emerged as the front runner. “Radionuclides still look like the sharpest signal,” says Zalasiewicz. The AWG summed up its current work in The Anthropocene as a Geological Time Unit, published in February by Cambridge University Press.

The quote above mentions both a growing population and a change in the way humans consume resources associated with “Great Acceleration” (Figure 7.1; Steffen et al., 2015). This chapter explores questions related to the causal mechanisms of this “Great Acceleration.” Climate change is associated with the great acceleration; however, it is not listed as one of the “Golden Spike” signals. Climate change may contribute to changes in the fossil record significantly by accelerating the mass extinction we are currently experiencing; however, climate change is not the only way humans are changing the earth’s environment. Nonetheless, climate change is a good example of a dramatic impact of human activity on the planet that is more related to the behavior of a small fraction of the population rather than being directly proportional to global population size.

[figure number=Figure 7.1 caption=The Great Acceleration filename=Fig_7.1.jpg]

Climate change results from the burning of fossil fuel that prior to the industrial revolution was sequestered in the earth’s crust. Is climate change driven by growing populations or growing levels of consumption? Today, the United States is responsible for roughly 13% of CO2 emissions annually; however, historically the United States is responsible for roughly 25% of all CO2 emissions since the onset of the industrial revolution. Both of these numbers are dramatically larger than the United States share of the global population, which is less than 5%. China, on the other hand, is now the global leader in annual CO2 emissions accounting for over 30% of emissions in 2021; however, cumulatively China only accounts for roughly 14% of emissions since the onset of the industrial revolution. Is China the global leader in CO2 emissions because of its affluence or the size of its population? These numbers alone raise thorny questions as to how to allocate responsibility for climate change and what policies should be imposed on what countries moving forward. To make this more complicated, there is a difference between “production-based” and “consumption-based” CO2 emissions. When countries set targets to measure or compare CO2 emissions, they tend to focus on production-based emissions, or CO2 emitted within a country’s borders. This fails to capture emissions from traded goods, which could be incorporated into the CO2 emitted in the production of goods elsewhere, which are later imported. In the United States, our consumption-based emissions exceed our production-based emissions by roughly 10%. Clearly, climate change is more a function of consumption than of population. However, climate change is not the only way humans are impacting the environment.

Agricultural land area currently accounts for roughly 40% of the earth’s land surface. While wealthy denizens of the developed world may emit orders of magnitude more CO2 than the people of the developing world, they cannot eat orders of magnitude more food. The environmental consequences of agriculture are much more directly related to the total size of the human population. This chapter explores several questions, including: (1) Is there an overpopulation problem? (2) Is there an overconsumption problem? (3) What might be a fair and ethical path forward with respect to addressing the two elements of the challenges we face? and (4) How can we fairly and objectively measure human impact on the environment in an “apples to apples to apples” framework?

Guiding Questions

Are sustainability challenges due to overpopulation, overconsumption, or both?

Explain why climate change is primarily attributed to a small fraction of the population.

Explain the I = P × A × T equation.

What was “The Bet” between Julian Simon and Paul Ehrlich all about?

Learning Objectives

Describe the “Great Acceleration” and explain the related but distinct ways that a growing population and growing levels of per capita consumption have an impact on the earth’s environment.

Provide an ethical answer to the population versus consumption question regarding the attainment of “sustainability.”

Defend an answer to the Overpopulation versus Overconsumption question.

Key Terms and Definitions

The Great Acceleration, I=P × A × T, The Anthropocene, The ecological footprint, Impervious Surface as a proxy measure of Human Impact, Net primary productivity (NPP), Proxy measure, Carrying Capacity, The Green Revolution, Limits to Growth, Debtor Nations, Ecological Surplus Nations, Human Appropriation of Net Primary Productivity (HANPP)

7.1 The Great Acceleration: Problem or Solution?

Charles Mann wrote a book titled The Wizard and the Prophet: Two Remarkable Scientists and Their Dueling Vision to Shape Tomorrow’s World (Mann, 2018; Video 7.1). Charles Mann chose to contrast the views of William Vogt (author of “Road to Survival”) and Normal Borlaug (father of the “Green Revolution”) as two representatives for dramatically different visions of a way forward for humanity. William Vogt is presented as a “Prophet” of coming doom if humanity does not address overpopulation as a fundamental problem. Vogt would regard the Great Acceleration as a problem. William Vogt is regarded as a “Neo-Malthusian” in this respect. Vogt’s book Road to Survival is regarded as a seminal work of the modern environmental movement (Vogt, 1949). Normal Borlaug, on the other hand, is presented by Charles Mann as a “Wizard” of human ingenuity. Borlaug is known for leading global initiatives that developed high-yield, disease-resistant wheat varieties that contributed to the profound increases in agricultural productivity associated with the green revolution. Borlaug is embraced by economists as an example of how technological innovation can solve our greatest problems.

“The Green Revolution” took place in the middle of the 20th century and prevented the starvation of millions and the possibility of life for billions. Borlaug was awarded a Nobel Peace Prize for this work in 1970. Charles Mann presents Borlaug as one who would regard the great acceleration as a solution, although Borlaug himself might not agree. It is perhaps interesting to note that even the “Wizard” himself had the long-term vision of a Neo-Malthusian as evidenced by this statement he made when accepting his Nobel Prize in 1970 “I have only bought you a 40-year breathing space to stabilize your populations.” This tense debate between what are often pessimistic biologists calling for restraint, and optimistic economists espousing innovation, is not particularly new.

Thomas Robert Malthus is likely the first to engage in the debate that took place among the economists, political philosophers, and writers of the late 18th and early 19th centuries about whether the benefits of scientific progress would be nullified by the growth of the global population. Paul Ehrlich and Julian Simon continued the debate in the 1970s with Julian Simon taking the proverbial role of “Wizard” and Ehrlich that of “Prophet.” Ehrlich and Simon engaged in a famous “bet” or “wager” in 1980. Simon challenged Ehrlich to choose any raw material he wanted and a date more than a year away, and he would bet that the inflation-adjusted prices would decrease as opposed to increase. Ehrlich chose copper, chromium, nickel, tin, and tungsten. The bet was formalized on September 29, 1980, with September 29, 1990 as the payoff date. Ehrlich lost the bet, as all five commodities that were bet on declined in price from 1980 through 1990. An apparent victory for the “wizards” point of view.

Julian Simon was happy to make more bets in this vein. Ehrlich and climatologist Stephen Schneider subsequently challenged Simon to bet on 15 current trends, betting $1,000 that each trend would get worse over a 10-year future period (Ehrlich & Ehrlich, 1998). The bets were on these trends:

The three years 2002–2004 will on average be warmer than 1992–1994.

There will be more carbon dioxide in the atmosphere in 2004 than in 1994.

There will be more nitrous oxide in the atmosphere in 2004 than in 1994.

The concentration of ozone in the lower atmosphere (the troposphere) will be greater than in 1994.

Emissions of the air pollutant sulfur dioxide in Asia will be significantly greater in 2004 than in 1994.

There will be less fertile cropland per person in 2004 than in 1994.

There will be less agricultural soil per person in 2004 than in 1994.

There will be on average less rice and wheat grown per person in 2002–2004 than in 1992–1994.

In developing nations, there will be less firewood available per person in 2004 than in 1994.

The remaining area of virgin tropical moist forests will be significantly smaller in 2004 than in 1994.

The oceanic fishery harvest per person will continue its downward trend and thus in 2004 will be smaller than in 1994.

There will be fewer plant and animal species still extant in 2004 than in 1994.

More people will die of AIDS in 2004 than in 1994.

Between 1994 and 2004, sperm cell counts of human males will continue to decline and reproductive disorders will continue to increase.

The gap in wealth between the richest 10% of humanity and the poorest 10% will be greater in 2004 than in 1994.

Julian Simon did not take this bet and he undoubtedly would have lost if he did. Most, if not all, of these trends grew worse over those 10 years. This did not phase Julian Simon. Simon did not accept the argument that these trends measure human progress or lack thereof. His rationale for not taking the bet (beyond his likely recognition that he would lose) was the following analogy:

Let me characterize their offer as follows. I predict, and this is for real, that the average performances in the next Olympics will be better than those in the last Olympics. On average, the performances have gotten better, Olympics to Olympics, for a variety of reasons. What Ehrlich and others says is that they don’t want to bet on athletic performances, they want to bet on the conditions of the track, or the weather, or the officials, or any other such indirect measure.

Julian Simon’s analogy seems to “cherry-pick” improvement by focusing on the world’s best athletes rather than the conditions under which most of us mere mortals must exist. Regardless of whether you accept Julian Simon’s analogy as appropriate or not it does seem that the evidence so far supports the worldview of the “wizards.”

In terms of Food, Water, and Energy, we have a track record of innovation that has more than kept up with population growth. With respect to food, we have evolved from hunter-gatherers to agriculture to the green revolution and are heading toward even higher yield genetically modified crops. In terms of water, we started by surviving on surface water, then moved on to building dams and pumping groundwater from aquifers, and will likely be getting more and more water from the desalinization of our oceans. Our use of energy has evolved from burning wood to burning coal, then to burning whale oil, followed by burning petroleum, adopting nuclear power, and currently, harnessing solar and wind power. The argument and worldview of the “wizards” certainly have an evidence-based track record. One counterargument is the idea that jumping off of a 13-story building can feel great until you get to the ground floor. Nonetheless, the debate continues. There are still wizards and prophets among us in the contemporary world.

It is not reasonable to make a list of all the contemporary “wizards”; however, a brief list is certainly warranted and instructive. Stephen Pinker (author of Better Angels of Our Nature), Hans Rosling (Public Health Professor extraordinaire), Peter Diamandis (X Prize Foundation), Jeffrey Sachs (author of The End of Poverty), and Ray Kurtzweil (Futurist with Google) all would likely be regarded as “wizards” who believe human ingenuity has and will continue to improve the human condition. A list of exemplary “Prophets” is also warranted and instructive. Johan Rockström (Stockholm Resilience Center), Garrett Hardin (author of The Tragedy of the Commons), Kenneth Boulding (author of Economics of Spaceship Earth), Donella Meadows (lead author of The Limits to Growth), and Bill McKibben (founder of 350.org) are all people who would likely be regarded as “Prophets” who believe in the idea that the human experiment is constrained by limits to growth and that we must live within limits that we can identify using science. Interestingly, Charles Mann suggests that the “Wizards” and “Prophets” should find common ground and acknowledge the truths that exist in each other’s world views. These men do seem to be in a never-ending and irreconcilable conflict as to the appropriate path to a just, sustainable, and desirable future. Many women, however, have been making progress that in some cases involves a healthy compromise between the contrasting worldviews of wizards and prophets.

7.2 Are Women Better Suited to Leading Us Toward a Just and Sustainable Future?

Consider the highly visible and oft-repeated concept of “Sustainable Development,” which is defined as “Development that meets the needs of the present without compromising the ability of future generations to meet their own needs.” The idea of sustainable development bridges the divide between “wizards” and “prophets” by incorporating a “prophet” value (sustainability) with a “wizard” value (development). This phrase was coined by a woman: Gro Harlem Brundtland (Chair of the Brundtland Commission). Brundtland was one of the first politicians to end subsidies to the fossil fuel industry and makes a good argument that these subsidies are anathema to sustainability (Video 7.2). There are many women who have been seeking solutions to our challenges in ways that bridge the gap between the wizards and the prophets. Elinor Ostrom was the first woman to win a Nobel Prize in Economics for her work challenging Garrett Hardin’s idea of “The Tragedy of the Commons” (Video 7.3). Her groundbreaking research identified ways that some people have organized themselves to manage a common pool of open access resources (Video 7.4). Vandana Shiva is an Indian physicist and social activist known for her work in the areas of sustainable agriculture and food sovereignty. Shiva’s physics background informs her understanding of our relationship to nature and the interconnectedness of everything (Video 7.5). Wangari Maathai established and fostered the “Green Belt” movement in Africa that resulted in the planting of over 45 million trees across Kenya to combat deforestation, stop soil erosion, and generate income for women and their families. Maathai was an amazing humanitarian who fought to stop the vicious cycle of environmental degradation and poverty (Video 7.6). Winona LaDuke is a Native American activist who has fought for land rights and argued that a people’s control of their land is essential to control their destiny (Video 7.7).

The COVID pandemic seems to be confirming what many policy analysts have suspected for some time: Women leaders may be more engaged on issues of social justice, environmental sustainability, and economic and technological innovation. If this is true, women leaders will foster societies that are more resilient to external shocks and enjoy higher levels of well-being (Coscieme et al., 2020). In 2018, a network of Wellbeing Economy Governments (WEGo), promoting new forms of governance that diverge from the ones on which the G7 and G20 are based, has been launched and is now a living project (Coscieme et al., 2019). Members of WEGo embrace three key principles of a well-being economy:

1. Live within planetary ecological boundaries,
2. Ensure equitable distribution of wealth and opportunity, and
3. Efficiently allocate resources (including environmental and social public goods; Video 7.7).

This brings well-being to the heart of policymaking, and in particular economic policymaking. This network has the potential to fundamentally transform existing global leadership that remains anchored to old economic paradigms that give primacy to economic growth over environmental and social wealth and well-being. Perhaps it is no surprise that the original three WEGo countries had women leaders: Nicola Sturgeon (Scotland; Video 7.8), Jacinda Ahern (New Zealand), and Katrin Jokobsdottir (Iceland).

7.3 Spatially Explicit Measures of Human Impact on the Planet

The transition from the 20th to the 21st century has seen an increasing awareness of humanity as an agent of significant and perhaps irreversible damage to the Earth’s ecological and environmental systems. Many of these concerns have been described and contrasted in documents with names like “The Millennium Ecosystem Assessment” (MEA) and “The United Nations Millennium Development Goals Report” (UNMDG). The eight human development goals outlined in the UNMDG (United Nations, 2008) are as follows:

1. To eradicate extreme poverty and hunger;
2. To achieve universal primary education;
3. To promote gender equality and empower women;
4. To reduce child mortality;
5. To improve maternal health;
6. To combat HIV/AIDS, malaria, and other diseases;
7. To ensure environmental sustainability;
8. To develop a global partnership for development.

The eight key findings of the MEA (Millennium Ecosystem Assessment (MEA), 2005) are as follows:

1. Humans depend on nature and ecosystem services for their health and security;
2. In the last half-century, people have made unprecedented changes to the planet’s ecosystems to meet rising demands for food, water, fiber, and energy;
3. These changes have improved many people’s lives; however, they have come at the expense of other primarily poor people and weakened nature’s ability to provide vital ecosystem services;
4. We are living beyond our means, 60% of the ecosystems studied are being degraded in unsustainable ways;
5. Pressures on ecosystems will grow significantly worse in the first half of the 21st century without dramatic changes in human attitudes and behaviors;
6. There is growing concern that many ecosystems could reach “tipping points” at which sudden and irreversible changes will have grave implications for human well-being;
7. We have the technology and knowledge to make needed changes to protect both ecosystems and human well-being;
8. In order to make these changes, we must stop thinking about nature’s services as free and limitless. These two comprehensive documents outline in a broad way the essence of the human–environment–sustainability problematic that scientists, scholars, and citizens have struggled with for decades.

In 2007 the group on Population, Development, and Reproductive Health of the UK Parliament issued a report titled “The return of the population growth factor: its impact upon the millennium development goals” (McCafferty, 2007). Sadly, this report concludes that many of the millennium development goals will be difficult or impossible to achieve if current population growth rates continue in the least developed countries. Many argue that recent neglect and indifference to the role of basic demographic processes as they pertain to the millennium development goals have created formidable problems that are getting worse faster (Campbell et al., 2007). It is perhaps ironic that the goals of the UNMDG and MEA are shared by diverse groups such as women’s rights activists, environmentalists, public health advocates, and those advocating population stabilization (Sachs, 2005). In addition, many of the policies aimed at improving maternal health, reducing child mortality, and improving the education opportunities for women result in reduced fertility rates, which in turn reduces the aggregate demand for food, water, fiber, and energy—the very activities that are damaging ecosystems.

Nonetheless, despite the MEA conclusion that we have the technology and knowledge to protect ecosystems and ensure human well-being, we are not pursuing and enacting these policies effectively. Public demand for the effective implementation of such policies seems to be driven more by physical evidence provided by earth scientists (e.g., CO2 concentrations in the atmosphere) than by social scientists (e.g., population projections and poverty rates from the United Nations and others). EO data (e.g., remotely sensed imagery and derived data products) is continuing to contribute to both the science and rhetoric that informs and drives public opinion regarding the human–environment–sustainability problematic.

EO data has contributed to our collective understanding of human impacts on the Earth in myriad ways. The famous “small blue planet” photograph (also known as “Earthrise”) taken by Apollo 8 astronauts in 1968 had a profound influence on how we see ourselves in a larger context (Borman et al., 1968). Images of deforestation in the Brazilian Amazon Basin derived from Landsat raised public awareness dramatically (Skole & Tucker, 1993). Imhoff, Haberl, and others have used satellite imagery in conjunction with other data sources to follow up seminal questions raised by Vitousek et al. (1986) to explore what fraction of the world’s net primary productivity (NPP) is being consumed by human action (Haberl et al., 2007; Imhoff et al., 2004; Imhoff & Bounoua, 2006). Images of the “Earth at night” derived from mosaics of hundreds of orbits of the Defense Meteorological Satellite Program’s Operational Linescan System (DMSP OLS) and now from the VIIRS (Visible Infrared Imaging Radiometer Suite) have captured the public imagination and have been incorporated into posters, news media weather presentations, and Google Earth (Elvidge, Baugh, Hobson et al., 1997; Sullivan, 1989).

Data products derived from images of the Earth at night have contributed to many studies that provide spatially explicit measurements and maps of human impacts on the Earth. Since the turn of the 21st century, many studies have used nighttime satellite imagery to explore various facets of human–environment interaction (Doll, 2008). Not surprisingly, there have been many studies examining the significant relationship between nighttime lights data products and population parameters such as urban extent, urban sprawl, and exurban development (Elvidge, Baugh, Kihn et al., 1997; Imhoff et al., 1997; Small et al., 2005; Sutton, 2003; Sutton et al., 2006). Urban areas are the most densely populated parts of the world and city lights data products have been used to map and estimate urban populations and intraurban population density (Sutton et al., 2001, 2003). Chris Doll has explored how nightlights imagery can be used as a proxy measure of nonpopulation-related socioeconomic phenomena such as CO2 emissions and economic activity (Doll, 2003; Doll et al., 2000). Numerous studies have used nocturnal imagery to map, estimate, and/or measure various facets of economic activity at a range of spatial scales (Ebener et al., 2005; Sutton & Costanza, 2002; Sutton et al., 2007). Others have explored data sets derived from nighttime imagery to produce maps of impervious surface area (ISA; Elvidge et al., 2004). ISA has also been identified as an important environmental indicator variable (Arnold & Gibbons, 1996) for such things as its impact on water quality (Carlson, 2008). These demonstrated capabilities of nighttime imagery of the Earth to serve as a proxy measure of human impacts on the environment and other socioeconomic phenomena have stimulated a lot of interest in the development of a NightSat mission (Elvidge, Cinzano et al., 2007).

A NightSat mission would be a satellite program designed explicitly to observe the Earth from space at night using sensors with higher spatial and spectral resolution. Recall that the DMSP OLS was designed in the late 1960s as a meteorological satellite to see sunlight and moonlight reflected off clouds. This data has been used to examine the potential of using a satellite-derived density grid of constructed area (aka ISA) in the calculation of national and subnational “ecological footprints.” Impervious surface is used as a proxy measure of human impact on the environment. ISA is a valid spatially explicit proxy measure of our ecological footprint.

Human beings around the world build, use, and maintain constructed surfaces for shelter, transportation, and commerce. “Paving the planet” is essentially a universal phenomenon that represents one of the primary anthropogenic modifications of the environment. Expansion in population numbers and economies combined with the popular use of automobiles has led to the sprawl of development and a wide proliferation of constructed surfaces. The percentage of people living in cities continues to rise, fed by the transport of food, water, fuel, consumer products, and building materials. There is wide agreement that humans have emerged as the primary agent of global change, but how can we measure and map our human ecological footprint and how does it vary spatially and temporally?

The ecological footprint is a well-established resource accounting tool that estimates how much biologically productive land and water area an individual or a spatially defined population uses to produce the resources it consumes and to absorb the wastes it generates based on prevailing technology and resource management practices (Wackernagel & Rees, 1996). Ecological footprint calculations have emerged as a valuable way to communicate and understand human impacts on the natural systems upon which we depend. They are also useful in modeling the longer-term impacts of human consumption—both on natural systems and society. One of the principles in calculating ecological footprints is that populations utilize widely distributed resources. This is a key consideration for urban populations since the land used to generate their food, fiber, and wood is widely distributed and could be halfway around the world. Similarly, the emissions of CO2 produced by fossil fuel burning are widely distributed. Another principle used in the calculation of ecological footprints is that it is not necessary to pinpoint the location that produces the resources used by a population. We pinpoint the location of where those resources are consumed using impervious surface as a proxy measure. Based on this measure of consumption, we calculate the quantity of land or water surface required to generate that quantity of consumption in terms of a normalized standard for biological productivity.

The Ecological Footprint’s widely used normalized standard measurement unit is the “global hectare” (GHA), defined as a biologically productive hectare with world average productivity. Kitzes et al. (2007) estimate that in 2003, the Earth made available 11.2 billion GHA, while maintaining humanity’s consumption depended on 14.1 billion GHA. Thus, humanity’s resource consumption in 2003 was rated at 25% more than the Earth was able to produce (Figure 1) in the same year. Another way to look at this number is that it took the Earth 15 months to produce the resources used by humanity in a 12-month period. When consumption exceeds production, the difference between the two numbers is made up by liquidating the Earth’s ecological stores and the accumulation of waste products such as CO2 in the atmosphere. These results and the ecological implications appear in a recent report issued by WWF International (2006).

While a growing number of organizations are producing estimates of ecological footprints, the Global Footprint Network (GFN) is the premier organization for establishing and updating the standards used and the GFN produces the most widely cited national and global ecological footprint estimates. The GFN assembles data from a wide range of sources to produce National Footprint Accounts, which record the resources consumed, CO2 emissions, and calculations of the land and water areas that are needed to produce the resources and absorb the CO2 that humans use. The data sources and modeling continue to evolve under the auspices of a standards committee and the GFN (Wermer, 2006). Each year national footprint accounts are updated to track the consumption of crop products, fibers, livestock, fish, timber, fuel wood, and CO2 produced. From these values, the model calculates the GHA utilization. The surface cover types that are tracked by national footprint accounts include cropland, grazing land, fishing grounds, forest land, built-up land, and “carbon land.” Land cover extents are drawn from multiple sources including CORINE, GAEZ, GLC 2000, and WCMC. Of these cover types, built-up land area estimates may be the least reliable data set and weakest for global comparison (Kitzes et al., 2007).

7.3.1 Using EO Data to Model Impervious Surface as a Proxy Measure of Ecological Footprint

A global grid of anthropogenically created impervious surface was derived from models using satellite-based estimates of constructed area. This grid is used is used as a spatially disaggregated proxy for the human ecological footprint. This global grid of constructed area density is based on satellite-derived nighttime lights and population count data for the United States only (Elvidge, Tuttle et al., 2007). This map of ISA was produced by obtaining 80 high-resolution aerial photographs from 13 cities around the United States. Each photograph had 100 random points classified as “impervious” (e.g., rooftop, sidewalk, parking lot, roadway, among others) or “not impervious” (e.g., lawn, park, golf course, among others). The number of “impervious” classifications for each photo was the calibrated value of the percent impervious surface for that image. Statistical models were applied using only the light intensity value from nighttime satellite imagery and population counts from the Landscan data product (Figure 7.2). Comparisons of this impervious surface product to a finer resolution product produced by the United States Geological Survey demonstrated the validity of this approach (Elvidge, Tuttle et al., 2007; Yang et al., 2003).

[figure number=Figure 7.2 caption=Methods for Producing Impervious Surface Model filename=Fig_7.2.jpg]

[figure number=Figure 7.3 caption=Impervious Surface Map of Earth Derived From EO Data filename=Fig_7.3.jpg]

Using a Geographic Information System (GIS), it is a relatively simple analysis to use this data to measure the total ISA on a country-by-country basis. Correlating the per capita ISAs with the per capita Ecological footprints of each country is a relatively simple task. The correlation is strong (Figure 7.4) with very high values for some Middle Eastern countries (e.g., UAE and Kuwait), and the United States, Canada, Finland, Sweden, and Norway. For a more detailed account of this study, see the article, Paving the planet: Impervious surface as a proxy measure of the human ecological footprint (Sutton et al., 2009).

[figure number=Figure 7.4 caption=Scatterplot of ISA versus Ecological Footprint for Nations of the World filename=Fig_7.4.jpg]

Earth Observation of I=PAT: Human Impact = Population × Affluence × Technology

Anthropogenic activity is now recognized as a significant driver of environmental change at local, regional, and global scales (Turner et al., 1990). These changes have come about as the human population has grown in size and developed in technology. This human–environment–sustainability problematic has generated numerous jeremiads (Kates, 1995). These jeremiads vary in nature from warnings about the loss of biodiversity (Wilson, 1992) to shortages of food and water (Malthus, 1798; Postel, 1997), the dwindling of energy supplies (Hubbert, 1956), and the damaging effects of climate change (Mastrandrea & Schneider, 2005). Despite the wide-ranging nature of warnings regarding the sustainability of human civilization today, a common neo-Malthusian thread pervades many if not most of these jeremiads. A widely used equation for capturing the idea of this neo-Malthusian thread is the I = P × A × T equation, which describes human Impact as the product of Population times Affluence times and Technology (Ehrlich & Holdren, 1971). This equation appeals to many because it recognizes that both population and consumption contribute to environmental impact. Unfortunately, the role of technology is very challenging to quantify appropriately. Holdren has proposed that the T (technology variable) becomes a more complex factor called CITE (the “Culture, Institutions, and Technology Effect”; Holdren, 1991).

EO data can be used as a very simple proxy for the I = P × A × T equation: pavement (e.g., constructed area or impervious surface). Pavement is a spatially explicit proxy measure of human impact on the environment because it captures many of these confounds and complexities associated with the “teasing apart” of problems associated with the separation of production and consumption in the world today (Brewer & Trentmann, 2006). This measure of constructed area is derived from a simple model using EO data and population counts. This global representation of impervious surface can be used as a proxy measure of many human impact-related variables such as energy consumption, urbanization, economic activity, and CO2 emissions. Al Gore’s highly publicized narration of the movie “An Inconvenient Truth” and the Stern report of 2007 (Stern, 2007) are seen by many as a “tipping point” in overall public conviction as to the reality and seriousness of the problems associated with climate change.

It is interesting and perhaps surprising to note that simple measurements of an extremely basic component of the atmosphere (CO2; Keeling et al., 1995) have most likely triggered more public awareness and acceptance of deleterious human impact on the Earth than the combined lamentations of prominent neo-Malthusian scholars such as Diamond (2005), Ehrlich and Ehrlich (1990), and Hardin (1968). The now famous “Keeling Curve” charting atmospheric CO2 concentrations over Mauna Loa in Hawaii over time (Keeling et al., 2004) is an interesting and poignant globally aggregate measure of anthropogenic impact on the planet.

In many respects, Keeling’s curve is like a planetary “idiot light” on the dashboard of a car telling humanity that something might be wrong. And, like the “idiot light” on the dashboard of a car, the “Keeling Curve” only provides a limited amount of information as to what the exact nature of the problem is and how it can be addressed. Nonetheless, “idiot lights” are invaluable devices if they trigger the following three responses: (1) Stop behavior that has serious potential negative consequences (i.e., continuing to drive a car with an overheating engine or allowing atmospheric CO2 concentrations to double); (2) diagnose what caused the “idiot light” to turn on; and (3) treat the cause (e.g., putting oil in the engine, coolant in the radiator, shifting to renewable energy supplies, among others).

The seemingly endless debates about the reality of global warming seem to be waning at this point, which suggests that these steps may be taken more forcefully in the not too distant future. Difficult questions arise when we have to decide which and whose behavior must change and how we hope to bring about those changes. The analogy between the “Keeling Curve” and an “idiot light” may hold some validity; however, the subsequent information needed to make diagnoses and change behaviors is more complicated than simply “looking under the hood.” Fortunately, there is an abundant amount of information in the form of EO data that can inform our understanding of the human–environment–sustainability problematic. In contrast to the globally aggregate measure that the CO2 data at Mauna Loa provides, EO data provide spatially explicit information that can be used as inputs for a suite of methods and analyses that enable more accurate measurement, mapping, and monitoring of human impacts on the Earth.

The 2007 National Research Council report titled Earth science and applications from space: national imperatives for the next decade and beyond (National Research Council (NRC), 2007). This report specifically identifies the requirement for measuring the “human footprint” on ecological systems. This quote from the report

Observations of Human Impacts

Human influences on the Earth are apparent on all spatial and temporal scales. Thus, an effective Earth information system requires an enhanced focus on observing and understanding the impact of humans, the influence and evolution of the built environment, and the study of demographic and economic issues. For instance, space-derived information on urban areas can provide a platform for fruitful interdisciplinary collaboration among Earth scientists, social scientists (e.g. urban planners, demographers, and economic geographers), and other users in the applications community. Data on the geographic “footprint” of urban settlements, identification of intra-urban landuse classes, and changes in these characteristics over time are required to facilitate the study of urban population dynamics and composition, and thereby to improve the representation of human-modified landscapes in physical and ecological process models. Because of the rapid growth in urban areas, particularly in the developing world where there are few alternative sources of information on urban extent and land cover, these observations are needed to understand a growing source of anthropogenic forces on regional weather and climate, air and water quality, and ecosystems, and to apply this understanding to protect society and manage natural resources.

Recommendation: Earth system observations should be accompanied by a complementary system of observations of human activities and their effects on Earth. (NRC, 2007)

Human impacts on ecosystems are myriad in nature and magnitude. While global representations of impervious surface cannot characterize the nature of these myriad impacts individually, they do provide a proxy measure of the magnitude of aggregate human impact for the entire planet at 1 km2 spatial resolution. The correlation between the relatively sophisticated ecological footprint indices and the relatively simple constructed area per person estimates derived from EO data suggests that satellite products constitute a legitimate, useful, and profound measure of human impacts on terrestrial ecosystems that can be updated and tracked over time.

During the environmental movement of the 1970s, the concept of I = P × A × T emerged as an equation for describing human impacts on the environment (Holdren, 1991; Holdren & Ehrlich, 1974). Global change research increasingly uses satellite imagery to focus on measuring, mapping, and quantifying a variety of forms of the Impact term of this equation. ISA derived from EO data demonstrates the viability of a satellite-based index that serves as a proxy measure of P × A × T. This index can be used to estimate the impact in the form of a “human ecological footprint,” acknowledging that impacts are widely distributed across the Earth (e.g., there is a complex separation of production and consumption). This measure of “impact” is spatially explicit, derived uniformly across the globe, and strongly correlates with measures of “ecological footprints” that are derived from a much more complex set of measurements.

7.4 Ecological Accounting and the “Real” Wealth of Nations

Adam Smith is regarded by many as the pioneer of political economy and his highly regarded work The Wealth of Nations is regarded as seminal in the field of economics. Economics is sometimes described as the study of the optimal allocation of scarce resources. As previously discussed, natural capital and ecosystem services are considered to be an increasingly important scarce resource that has historically been undervalued—particularly by economists who dominate the policy domain in most developed countries. Here, we will look at the idea of “carrying capacity” as a fundamental ecological indicator of biophysical sustainability for humanity. By mapping carrying capacity, we can identify where ecological resources are being overexploited. Most countries of the world exist in an ecological deficit with respect to an ecological accounting of human impact relative to natural capital. Identifying the appropriate scale or magnitude of human impact is an important avenue of inquiry in the field of ecological economics and it can prove useful in illuminating aspects of the overpopulation vs. overconsumption question.

Following the publication of Aldo Leopold’s A Sand County Almanac in 1949, Rachel Carson’s Silent Spring in 1962, and Paul and Anne Ehrlich’s The Population Bomb in 1968, the early 1970s were a time of rapidly expanding consciousness of issues associated with environmental degradation and human responsibility for those impacts on the environment. In 1969, the Cuyahoga River in Cleveland Ohio caught on fire and there was a significant oil spill in the Santa Barbara Channel. These events likely contributed to precipitating the first “Earth Day” celebration in 1970. However, oil spills and rivers catching on fire are perhaps not the preferred sort of “ecological indicator” to help us guide environmental and economic policy.

Approximately 1 year after the first “Earth Day” celebration, Paul Ehrlich and John Holdren published the important aforementioned conceptual article titled Impact of population growth. This article postulated an oft-cited equation: I = P×A×T (where “I” is Impact, “P” is Population, “A” is Affluence, and “T” is Technology (Holdren & Ehrlich, 1974). Questions about human impact on the environment remain with us today and are perhaps even more pressing in light of global climate change, dwindling nonrenewable resources, and the rapid loss of biodiversity. These questions are often framed within the broader context of “Sustainability.” In a strictly biophysical sense, “ecological sustainability” is perhaps a more palatable way of expressing the idea of “Carrying Capacity.”

Debates regarding the validity of the concept of carrying capacity are highly contested and ongoing (Sayre, 2008). Contemporary definitions of human carrying capacity were adapted from ideas about how many cattle a given area of rangeland could support and now include additional variables: “. . . the population of humans that can be sustained by a given ecosystem at a given level of consumption, with a given technology” (Daly & Farley, 2004). It is now generally accepted that variations in areas of technology, ecosystems, and consumption complicate attempts at steady-state equilibrium estimates of carrying capacity for humans (Cliggett, 2001).

While the idea of a global “carrying capacity” for humans may be a taboo idea in particular (Hardin, 1978), ideas such as “sustainable development” (United Nations, 1987) and “ecological footprint” (Wackernagel & Rees, 1996) have been increasingly incorporated into public discourse. These ideas of “sustainability” and “ecological footprint” implicitly encompass contemporary ideas of carrying capacitywhich incorporate some of the complexities of varying ecological environments, technologies, and consumption patterns. From the perspective of population geography, it is useful and informative to develop a simple spatially explicit measure of ecological sustainability (or carrying capacity if you will) that involves the use of valid proxy measures of Human Impact and Biocapacity.

The proxy measures used for these two measures are (1) anthropogenic ISA and (2) NPP. ISA is used as a measure of human “demand” on the planet and NPP is used as a measure of “supply” provided by the planet. We described ISA before as those land surfaces that have been transformed by human action to impervious surfaces (e.g., paved streets and highways, parking lots, rooftops, sidewalks, etc.). ISA is used as a spatially explicit proxy measure of human impact or “demand” in the spirit of the I = P × A × T model proposed by Ehrlich and Holdren (1971; Figure 7.5). NPP is used as a spatially explicit proxy measure of the earth’s recurring or renewable natural endowment (Figure 7.6). NPP is in essence a simplified proxy measure of the earth’s ecosystem services (de Groot et al., 2002). The total dollar value of the world’s ecosystem services and natural capital has been estimated to be over 50 trillion dollars per year (Costanza et al., 1997). This oversimplification results in a global, spatially explicit model of “supply” and “demand” on the earth. For simplicity, they are set as equal to one another globally at a value of $50 trillion (roughly the global Gross Domestic Product [GDP] in the year 2000). The title of this section of the book pokes a little fun at Adam Smith’s seminal and brilliant work (Smith, 1776) because we believe ecosystem services represent a market failure that rivals the global economy in terms of its sheer magnitude.

[figure number=Figure 7.5 caption=Anthropogenic Impervious Surface Area (ISA) Monetized to $50 Trillion for the year 2000 filename=Fig_7.5.jpg]

[figure number=Figure 7.6 caption=Net Primary Productivity (NPP) Monetized to $50 Trillion for the year 2000 filename=Fig_7.6.jpg]

Ecosystem services are associated with market failures because ecosystem services are in many cases public goods in and of themselves, are affected by both positive and negative externalities, and have problems associated with unclear property rights definitions. Ecosystem services and natural capital are often overlooked or ignored despite their critical importance to the sustainable functioning of the Earth (Daily, 1997). Costanza et al. (1997) took a careful look at the total global value of ecosystem services and natural capital and noted that “because ecosystem services are not fully captured in commercial markets or adequately quantified in terms comparable with economic services and manufactured capital, they are often given too little weight in policy decisions.” Given the critical role ecosystem services play in the quality of human life, it is essential that we have methods for considering natural capital and related ecosystem services in our policy decisions.

Incorporating ecosystem service values into measures of sustainability is challenging for several reasons. Research on ecosystem service valuation has explored complexities associated with problems that spatial context presents with respect to valuation (i.e., the economic value of the erosion control services provided by a boreal forest in location A near a reservoir are likely not the same as those provided in location B far from any built infrastructure). For example, the storm protection provided by coastal wetlands changes with the spatial context of storm frequency, built infrastructure, and other nearby wetlands (Costanza et al., 2008). Estimation of the dollar value of ecosystem services is a daunting task for numerous reasons including problems of spatial context, contingent valuation, and sins of omission. Making spatially explicit estimates of the sum of all ecosystem service values is also difficult because some benefits (e.g., carbon sequestration) are not spatially localized, whereas other benefits are (e.g., storm protection services). Consequently, this approach maps the dollar value of the earth’s recurring natural endowment (i.e., ecosystem services) using the basic widespread and relatively easy-to-measure natural benefit we call photosynthesis (aka NPP).

NPP is a fundamental measure of the recurring conversion of light energy into human-ingestible chemical energy provided by the earth’s ecosystems. Imhoff et al. (2004) developed a global map of Human Appropriation of Net Primary Productivity (HANPP). One goal of this map is to identify areas suffering from severe human impact, since “changing patterns of HANPP will have important consequences for human welfare and global biodiversity” (Imhoff et al., 2004). They found that globally, humans appropriate about 20% of terrestrial NPP. However, this appropriation of NPP varies significantly around the world. Areas including Western Europe and South-Central Asia consume more than 70% of the local NPP, while other areas including South America use about 6% of their local NPP. Ultimately, “spatially explicit measures of HANPP [. . .] will help to illuminate current human impacts on the biosphere, monitor changes in these impacts over time and explore the potential of various policies for alleviating them” (Imhoff et al., 2004).

This approach draws from this work on HANPP by placing a dollar value on the NPP itself and presenting a broader spatially explicit model for human impact (monetized anthropogenic ISA). This presents a new method for measuring anthropogenic environmental impact, which is monetized as an environmental cost. This is achieved using existing global maps of Net Primary Production (NPP) and ISA. The implicit assumption of setting these two global values to the same number ($50 trillion) is that human impact on the world is balanced by the earth’s ability to absorb that impact. This equality assumption is in essence an assumption that humanity is presently at carrying capacity and this assumption would likely be contested by many (Brown, 2009; Cohen, 1995; Wackernagel & Rees, 1996).

We make this simplifying assumption primarily because it is conceptually simpler and the resulting table of national deficits and surpluses will necessarily have a zero sum. The final map presents national ecological surpluses or deficits (in U.S. dollars). The data is summarized at the country level for easy comparison with other data sets such as poverty estimations, environmental sustainability indexes, and Eco Deficits. The model presented here uses a simplifying albeit arbitrary axiom that the earth is presently at “carrying capacity” (i.e., globally, human impacts on the environment are balanced by the environment’s ability to absorb those impacts). This axiom of the model can be easily adjusted to “set” human impact at 0.75-, 1.5-, or 3.0-times carrying capacity.

It would be simple to produce scaling factors that would generate similar spatially explicit numbers using any corrective factor derived from other studies and/or metrics of sustainability. Other metrics that could be used include the ecological footprint itself, population to arable land ratios, freshwater availability, HANPP, etc. The power of this model is not the idea that the ratio of pavement and photosynthesis represents a fundamental measure of ecological sustainability but that ISA and NPP are valid proxy measures of human impact and ecosystem services that are relatively easy to map and measure globally.

7.4.1 Ecological Debtor and Ecological Surplus Nations

There are nations on both sides of the ecological balance of this analysis. Those nations that have an “Impact” (derived from the ISA dataset) that exceeds their biocapacity (aka “Ecological Endowment) derived from the NPP dataset are regarded as “Ecological Debtor” nations. Those whose “impact” is less than their endowment are regarded as “Ecological Surplus” nations. These results are obtained by summing the monetized ISA and monetized NPP images to national levels using a GIS. The $50 trillion number was chosen because it is within the range of the total global value of ecosystem services estimated by Costanza et al. (1997) and because this number is approximately the global GDP for the year 2000. In addition, the ISA data set is for the year 2000. The images were converted to equal area projections at the same spatial resolution and subtracted as follows:

NPP (monetized to $50 trillion) – ISA (monetized to $50 trillion) = Ecological Balance

(i.e., Natural Production “supply” minus Human Impact “demand” = National Surplus or Deficit)

This resulted in an image in which urban areas were generally in ecological deficit and non-urban vegetated areas were generally in ecological surplus. Not surprisingly, uninhabited deserts showed neither surplus nor deficit. Summing the resulting image to national levels of aggregation provided results at the aggregated national level. For each country, the following numbers were calculated: Total Value of NPP ($NPP), Total Cost of ISA ($ISA), the difference between $NPP and $ISA (Eco-Balance), and Eco-Balance per capita (EB/capita; Figure 7.7; Tables 7.1 and 7.2). For a more detailed description of this analysis, see the article titled: Thereal wealth of nations: Mapping and monetizing the human ecological footprint (Sutton et al., 2012).

[figure number=Figure 7.7 caption=Net Primary Productivity (NPP) Monetized to $50 Trillion for the Year 2000 filename=Fig_7.7.jpg]

Country	Population	Area (km2)	Person/km2	NPP as dollars	ISA as dollars	Ecological balance	EcoBalance/person
Brazil	151,525,400	8,507,128	18	5,860,550,259,500	1,535,838,910,500	4,326,711,349,000	28,554
Russia	151,827,600	16,851,940	9	4,041,500,634,400	1,476,348,163,000	2,565,152,471,400	16,895
Congo, DRC	51,965,00	2,345,410	22	2,308,849,664,000	228,567,691,200	2,060,281,972,800	40,032
Australia	17,827,520	7,706,142	2	2,166,939,454,000	231,306,084,100	1,935,633,429,900	106,576
Canada	28,402,320	9,904,700	3	2,345,808,238,100	973,042,296,100	1,373,365,942,000	48,368
Angola	11,527,260	1,252,421	9	895,471,505,700	30,701,904,700	864,769,601,000	75,020
Peru	24,496,400	1,296,912	19	977,564,982,600	135,751,986,900	841,812,995,700	34,365
Colombia	34,414,590	1,141,952	30	973,137,393,100	284,495,371,300	588,641,021,800	20,010
Argentina	33,796,870	2,781,013	12	1,029,988,910,100	407,692,894,800	622,296,015,300	18,413
Bolivia	7,648,315	1,090,353	7	657,371,896,400	53,305,294,490	604,056,599,910	78,980
Venezuela	19,857,850	916,561	22	810,400,800,100	270,745,731,900	539,655,068,200	27,175
Zambia	8,778,681	754,773	12	569,490,092,200	42,025,947,610	527,454,144,590	60,085
Tanzania	35,306,000	945,090	37	649,069,756,300	146,454,093,500	502,615,662,800	14,236
Central African Republic	3,149,545	621,499	5	504,990,026,400	10,211,150,560	494,778,875,840	157,095
Mozambique	16,601,660	788,629	21	525,169,385,800	60,261,776,990	464,907,608,810	27,999
Indonesia	189,331,200	1,910,842	99	1,817,413,439,600	1,429,719,620,200	441,693,819,400	2,333
Papua New Guinea	4,039,033	466,161	9	444,236,634,700	23,017,645,370	421,218,969,330	104,287
Sudan	27,713,420	2,490,0409	11	537,214,921,200	157,544,215,500	379,670,705,700	13,700
Madagascar	13,046,690	594,856	22	434,241,496,200	74,230,216,400	360,011,279,800	27,594
Congo	2,318,276	345,430	7	361,053,474,600	13,193,187,070	347,860,287,530	150,051
Table 7.1: Top 20 countries with the largest ecological surplus in the year 2000

Country	Population	Area (km2)	Person/km2	NPP as dollars	ISA as dollars	Ecological balance	EcoBalance/person
India	894,608,700	3,089,282	290	1,318,571,346,200	7,012,537,036,300	−5,693,965,690,100	−6,365
China	1,281,008,318	9,338,902	137	2,662,914,738,900	7,342,438,979,500	−4,679,524,240,600	−3,653
United States	258,833,000	9,450,720	27	3,308,986,500,100	7,246,569,183,500	−3,937,582,683,400	−15,213
Japan	125,746,300	373,049	337	221,450,517,500	1,205,271,117,200	−983,820,599,700	−7,824
Pakistan	126,693,000	877,753	144	105,015,078,200	919,936,455,000	−814,921,376,800	−6,432
Bangladesh	120,732,200	138,507	872	70,559,994,240	769,090,784,400	−698,530,790,160	−5,786
Germany	81,436,300	356,109	229	174,449,868,000	731,627,852,100	−557,177,984,100	−6,842
Italy	57,908,880	300,980	192	160,054,464,000	714,599,650,900	−554,545,186,900	−9,576
United Kingdom	56,420,180	243,137	232	123,103,601,100	652,264,827,100	−529,161,226,00	−9,379
Iran	64,193,450	1,624,760	40	84,144,201,690	598,284,006,00	−514,139,804,310	−8,009
France	57,757,060	546,729	109	333,820,137,700	821,151,541,300	−487,331,403,600	−8,438
Egypt	56,133,430	982,910	57	16,581,983,920	495,694,541,100	−479,112,557,180	−8,535
Spain	39,267,780	505,974	78	245,061,777,900	606,751,411,400	−361,689,633,500	−9,211
Saudi Arabia	18,099,990	1,960,175	9	5,020,630,739	349,377,198,000	−344,356,567,261	−19,025
South Korea	43,410,900	98,339	441	52,987,677,360	387,063,600,300	−334,075,922,940	−7,696
Nigeria	97,228,750	912,039	107	359,879,633,300	662,721,227,800	−302,841,594,500	−3,115
Poland	37,911,870	310,715	122	137,733,810,900	364,390,832,700	−229,657,021,800	−6,058
Vietnam	71,215,210	327,123	218	289,663,375,600	515,192,031,700	−225,528,656,100	−3,167
Philippines	65,981,120	298,134	221	277,171,911,700	466,853,553,300	−189,681,641,600	−2,875
Turkey	61,300	779,986	79	243,934,934,000	426,053,022,500	−182,118,088,500	−2,971
Table 7.2: Top 20 countries with the largest ecological deficit in the year 2000

 

The twenty countries with the largest surplus Ecological Balance tended to be large, forested countries that nonetheless have relatively large populations (Table 7.1). Brazil’s surplus of $4.3 trillion represents almost 9% of the total global value of monetized NPP. Only Canada, Australia, Congo, DRC, and Russia had surplus Ecological Balances that exceeded a trillion dollars (Table 7.1). The 20 countries with the largest deficit Ecological Balance tended to be large populous and or wealthy countries with India, China, and the United States in the top three “debtor nation” spots with deficit Ecological Balance figures of $5.7, $4.6, and $3.9 trillion, respectively (Table 7.2). Japan’s deficit approaches a trillion dollars but falls just short.

The areas with highest surplus values are found in Russia, Brazil, Australia, Canada, Central Africa, Central America, and parts of Southeast Asia. These regions are operating their national economies below the carrying capacity of their respective national ecosystems. This follows an expected pattern, based on the high NPP values in these areas of tropical rainforest combined with relatively low levels of consumption. However, many of these areas are rapidly deforesting and losing vital ecosystem services associated with highly productive tropical rainforests that provide valuable ecosystem services such as climate regulation, erosion control, and the provision of raw materials (Achard et al., 2002; Costanza et al., 1997; Malhi et al., 2009).

In Northern Africa and the Middle East, where human development and consumption levels are relatively low, the natural production values are also low. These desert environments are not endowed with an ecological surplus, so they cannot sustain high levels of human consumption and environmental impact without drawing on natural resources from other regions. For example, Phoenix, Arizona, is struggling with scarcity of water resources in the face of high demand for landscaping and human use (Farber et al., 2006). Quite simply, low levels of rainfall and high evapotranspiration limit the amount of biomass these areas can support, and by extension, the amount of NPP.

In regions such as North America, China, India, and Europe, the map shows ecological deficits, which suggests that high levels of human development and population are exceeding natural production values. The economies of these countries have an impact on the environment that is greater than the environment’s ability to sustain itself; national production and consumption levels have overshot ecological capacity. Indeed, “if international trade suddenly ceased, [these] countries would find themselves well beyond sustainable scale” (Daly & Farley, 2004, p. 333).

The ecological balances (derived from NPP minus ISA) were joined with other measures of Ecological Deficit and poverty estimates. While it was thought that poverty might correlate with NPP, as areas with lower natural production would not have a large resource base to support high consumption levels, the relationship was not found to be very strong. Poverty can be associated with areas of high NPP (e.g., Central Africa) and areas of low NPP (e.g., the Middle East). People inhabiting Central Africa do not benefit from the regional surplus of natural production, as the goods and services provided by rainforests and mineral deposits are largely exported to more developed countries.

For example, China—a country exhibiting an ecological deficit—increasingly relies upon tropical African countries for timber and nonrenewable resources. China initiated “resource for infrastructure” swaps that allow them to mine copper and cobalt in exchange for building roads and schools in countries such as Gabon and the Democratic Republic of the Congo (French, 2010; Laurance et al., 2006). China has become the biggest investor in Africa, using Africa’s wealth of renewable and nonrenewable natural resources to supply growing global demands for goods.

The United States and Europe tend to have high human impacts and low natural production values. Places like Brazil and Central Africa tend to have low human impacts and high natural production values. However, the interconnected global economy allows more developed (or even overdeveloped) countries to harness the ecological surpluses from many tropical countries. Raw material extraction has been increasingly outsourced to countries with the lowest environmental standards in a global “race to the bottom” in the quest for resources (Daly & Farley, 2004). Ecological accounting provides a sense of global flows of goods, but it also shows what countries are providing global (and often ignored or undervalued) ecosystem services. These differentials drive an increasing level of what is being called “Land Grabbing” where countries in ecological deficit are extracting ecosystem services from countries with an ecological surplus (Coscieme et al., 2016). Tropical rainforests are one of the most important terrestrial providers of ecosystem services (Costanza et al., 1997); yet, globally it is estimated that about 6 million acres of rainforest were lost annually between 1990 and 1997 (Achard et al., 2002). Countries with large swaths of tropical forest face increasing demands for goods. One example is Gabon, which has exhausted its oil reserves and is replacing that lost income through increased exploitation of forest resources (Laurance et al., 2006). While these rainforests are being harvested for their stocks, global benefits from climate regulation, nutrient cycling, and carbon uptake are lost—potentially forever. As Costanza et al. (1997) noted, “if significant, irreversible thresholds are passed for irreplaceable ecosystem services, their value may quickly jump to infinity.”

It is vital that humans do not push ecosystems beyond that critical tipping point. We examine the relationship of NPP and ISA as it relates to poverty; however, we do not assume that each national ecological balance determines poverty. However, poor deficit countries are more likely to be ecologically vulnerable than wealthy deficit countries. Developing a global indicator for monetizing ecosystem services raises the question of what level of accuracy is possible and/or desirable. We are confident that we do a better job valuing ecosystem services than the unregulated market; however, if an ecosystem service is irreplaceable or can be irreversibly damaged, then it is important to consider whether or not it is beneficial to place a market value on that ecosystem service at all.

Economic valuation of ecosystem services is not designed as a mechanism for commodification of these services, which are a common pool resource in many respects. The notion that ecosystem services must be assigned a monetary value so they can be included in the market is anathema to the spirit of this exercise. At their very core, particularly with increasing scarcity, ecosystem services are irreplaceable. In all likelihood, auctioning off ecosystem services would not provide adequate compensation to all those impacted by the rapid loss of critical functions (e.g., water filtration, nutrient cycling, carbon sequestration, etc.). The market cannot adequately price these services; while it must be recognized that ecosystem services have a monetary value, the market should not be in charge of allocating the services. Ecosystem services undergird provisioning, regulating, cultural, and supporting processes that are essential to human life and therefore should not be considered as a renewable resource, which is how they are treated currently within the market (Newman & Jennings, 2008).

Part of the motivation for developing this new method of measuring global consumption of ecosystem services is that, whether the market acknowledges it or not, there are limits to environmental systems for the production of resources, and more importantly, there are limits to the global sinks that absorb the waste produced around the world (Daly & Farley, 2004). There are several paths of exploration that are likely worth future examination. It would be beneficial to compare ecological balances with GDP at the national scale. It would also be useful to explore the relationship between HANPP and ecological balances. It seems that this data and HANPP might help answer different questions within the same field of study and could be used together to better answer questions and inform policy decisions.

In order to examine how countries export the environmental impact of national consumption, it might be interesting to compare ecological balances with the importance of basic export goods to a nation’s economy. The productivity of marine ecosystems was not included in this analysis. Nevertheless, open oceans and coastal ecosystems constitute very important sources of ecosystem services and NPP (Costanza et al., 1997). While national ecological balances might change when ocean productivity is incorporated into natural production, humans are dramatically impacting the ability of ocean ecosystems to perform critical ecosystem services due to climate change, unrelenting pollution, and overfishing. It is not unreasonable to foresee diminishing natural production from these overexploited ocean resources.

Another area of concern is that NPP might change dramatically as a result of droughts, flooding, and severe storms associated with climate change (Krugman, 2010). These impacts could have significant impacts on local and regional ecosystems. It is certainly not beyond the realm of possibility that many countries could see dramatic reductions in NPP and slide deeper into ecological debt. Operating at full capacity could irreparably damage the ecosystems upon which all human beings rely. A serious challenge to those of us studying issues of sustainability is understanding how ecological sustainability has changed (and will continue to change) in time and space. Coming to understand the complex ecological processes that take place within a cubic meter of rainforest is a monumental challenge unto itself (let alone trying to communicate those processes and their importance to the public). Despite the oversimplifications inherent in this approach to the global mapping of ecological sustainability, it is nonetheless useful, comprehensible, rhetorically powerful, and scientifically valid.

We have the capability to map ISA and NPP at moderate spatial resolution (1 km²) on at least an annual basis if not more frequently. Future studies of sustainability could utilize these and other EO data capabilities to inform our understanding of the spatiotemporal dynamics of ecological sustainability. This work is consilient with some of the spirit of the report on The Economics of Ecosystems and Biodiversity (TEEB) whose lead author eloquently described fundamental problems with the dominant neoclassical economic paradigm through which so much policy is based “we are trying to navigate uncharted and turbulent waters with an old and defective economic compass and this is affecting our ability to forge a sustainable economy in harmony with nature” (Sukhdev, 2009).

Specifically, this kind of analysis will inform both policymakers and the public about the nature, magnitude, potential dollar value, and spatial patterns of human impacts on the environment. The TEEB argues that the natural world provides services that have enormous economic value that is generally ignored. This metric informs attempts to improve indicators and accounting systems for understanding the spatial and temporal variation in the dynamics of natural capital.

This kind of analysis is a new step toward a much needed “ecological accounting” at the global scale (Global Footprint Network, 2006; Wackernagel et al., 2002). Spatially explicit analyses of this nature assume that we are operating our global economy at full capacity relative to ecosystem services; however, this is not the case. Indeed, countries in an ecological deficit are already stretched beyond their national means. Increasing consumption and growing populations are also drawing down stocks of nonrenewable minerals and fossil fuels. It is more likely that the current level of global economic activity far exceeds sustainable limits. In any case, it is clear from the standpoint of an ecological assessment of the impact of the nations of the world on the earth’s biocapacity that there are wealthy countries in ecological deficit (e.g., the United States and most of Western Europe), there are wealthy countries in ecological surplus (e.g., Canada and Australia), there are poor countries in ecological deficit (e.g., India), and poor countries in ecological surplus (e.g., Democratic Republic of Congo). Clearly, achieving sustainability demands that we recognize that both population and consumption must be addressed simultaneously. In some parts of the world, our focus will be more on consumption, whereas in other parts of the world, it will be more focused on population. Pretending that the sustainability challenge is an “OR” question of population “or” consumption is a false and ultimately ineffective narrative.

7.4.2 The Limits to Growth and the Population–Environment–Sustainability Problematic

The original Limits to Growth report is now 50 years old at the time of this writing in 2022. The message of the limits to growth was and is pretty simple. The human population cannot grow indefinitely, nor can the economy grow indefinitely. This message has not been well received or embraced over the last 50 years. The worldview of economists is predicated and depends upon perpetual economic growth. Economists vigorously ridiculed the simple and irrefutable message of the limits to growth while dominating the policy development and political economy of most nations of the world. This has brought us to the state of the world we are currently living in. The dominant neoliberal economic worldview has clouded our ability to clearly understand the population–environment–sustainability problematic accurately and appropriately.

Steven Chu is a Nobel Prize-winning physicist who served as the Energy Secretary under President Obama, a professor of Physics at Stanford University, and the president of the American Association for the Advancement of Science. Steven Chu is an accomplished and brilliant scientist and administrator who was instrumental in solving the Deepwater Horizon oil spill crisis that took place in the Gulf of Mexico in 2010 (Green, 2010). Steven Chu has provided some thoughts on the role of economics as it pertains to the population–environment–sustainability problematic that are consilient with the ideas in this book.

This article written by Jeff McMahon in Forbes Magazine in 2019 summarized Steven Chu’s assessment of the economic nature of the population–environment–sustainability problematic (McMahon, 2019).

The world economy is based on ever-increasing population, said Nobel laureate Steven Chu, a scheme that economists don’t talk about and that governments won’t face, a scheme that makes sustainability impossible and is likely to eventually fail.

Summary/Key Takeaways

There is a debate as to whether population growth or high per capita levels of consumption are the driving force of environmental degradation and our failure to achieve sustainable development. This chapter posits that neither population growth nor increased per/capita levels of consumption are sustainable. The population–environment–sustainability problematic manifests differently in various parts of the world. An analysis of the variability of human impact on the environment juxtaposed with the ecosystem services provided by the earth’s terrestrial ecosystems suggests that most countries of the world are beyond their carrying capacity and this can be because of excessive resource consumption OR because of overpopulation or both. Thus, the question Overpopulation or Overconsumption? is a false dichotomy that does not capture the fundamental idea of the Limits to Growth that suggests neither the population nor the economy can grow forever. Sustainability cannot be achieved without a recognition that there are limits to growth that can be identified using scientific laws rather than economic fairy tales.

Comprehension Questions

• Explain Charles Mann’s idea that there are “Wizards” and “Prophets” with dramatically different ideas about how humanity should achieve a just, sustainable, and desirable future.
• How is “ISA” used as a measure of human impact on the environment?
• Explain the I = P × A × T equation.
• What is NPP and what is HANPP?
• Name five women who have made significant contributions to charting a path to a just, sustainable, and desirable future and describe the nature of their contributions.
• What countries embrace the idea of a well-being economy and what is unusual about their political leadership?
• In 1972 there was a report produced by the Club of Rome titled “The Limits to Growth.” What did it say? Who opposed the message in the report? And, how did the world collectively respond to the warnings in the “Limits to Growth” report?
• Why is the question What drives our inability to achieve sustainable development population growth or increasing per capita resource consumption? a false dichotomy?
• Describe some anthropogenic impact on the hydrosphere, lithosphere, biosphere, and atmosphere.
• Identify a country that falls into each of these categories: (1) In ecological surplus and high levels of per capita resource consumption; (2) in ecological surplus with low levels of per capita resource consumption; (3) in ecological deficit with high levels of resource consumption; (4) in ecological deficit with low levels of resource consumption. Explain how the different situations of these four countries can inform questions about the population–environment–sustainability problematic.

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