Future societies will also face challenges arising from resource scarcity and accumulating pollutants. Many specific examples of these broad categories of problems are discussed in detail in the following chapters. This section provides a flavor of what is to come by illustrating the challenges posed by one pollution problem (climate change) and one resource scarcity problem (water accessibility).
Climate Change
Energy from the sun drives the earthâs weather and climate. Incoming rays heat the earthâs surface, radiating heat energy back into space. Atmospheric âgreenhouseâ gases (water vapor, carbon dioxide, and other gases) trap some of the outgoing energy.
Without this natural âgreenhouse effect,â temperatures on the earth would be much lower than they are now and life as we know it would be impossible. It is possible, however, to have too much of a good thing. Problems arise when the concentration of greenhouse gases increases beyond normal levels, thus retaining excessive heat somewhat like a car with its windows closed in the summer.
Since the Industrial Revolution, greenhouse gas emissions have increased, considerably enhancing the heat-trapping capability of the earthâs atmosphere. According to the U.S. Global Change Research Program (USGCRP) (2014):1
Evidence from the top of the atmosphere to the depths of the oceans, collected by scientists and engineers from around the world, tells an unambiguous story: the planet is warming, and over the last half century, this warming has been driven primarily by human activityâpredominantly the burning of fossil fuels.
As the earth warms, the consequences are expected to affect both humans and ecosystems. Humans are susceptible to increased heat, as shown by the thousands of deaths in Europe in the summer of 2003 due to the abnormal heat waves. Human health can also be affected by diseases such as Lyme disease, which spread more widely as the earth warms. Rising sea levels (as warmer water expands and previously frozen glaciers melt), coupled with an increase in storm intensity, are expected to flood coastal communities with greater frequency. Ecosystems will be subjected to unaccustomed temperatures; some species will adapt by migrating to new areas, but many others are not expected to be able to react in time. While these processes have already begun, they will intensify throughout the century.
EXAMPLE 1.1
A Tale of Two Cultures
The Mayan civilization, a vibrant and highly cultured society that occupied parts of Central America, did not survive. One of the major settlements, CopĂĄn, has been studied in sufficient detail to learn reasons for its collapse.
After AD 400 the population growth began to bump into an environmental constraint, specifically the agricultural carrying capacity of the land. The growing population depended heavily on a single, locally grown cropâmaizeâfor food. By early in the sixth century, however, the carrying capacity of the most productive local lands was exceeded, and farmers began to depend upon more fragile parts of the ecosystem. Newly acquired climate data show that a two-century period with a favorable climate was followed by a general drying trend lasting four centuries that led to a series of major droughts. Food production failed to keep pace with the increasing population.
By the eighth and ninth centuries, the evidence reveals not only high levels of infant and adolescent mortality but also widespread malnutrition. The royal dynasty, an important source of leadership, collapsed rather abruptly sometime about AD 820â822.
The second case study, Easter Island, shares some remarkable similarities with both the Mayan case and the Malthusian vision. Easter Island lies some 2000 miles off the coast of Chile. Current visitors note that it is distinguished by two features: (1) its enormous statues carved from volcanic rock and (2) a surprisingly sparse vegetation, given the islandâs favorable climate and conditions. Both the existence of these imposing statues and the fact that they were erected at a considerable distance from the quarry suggests the presence of an advanced civilization, but current observers see no sign of it. What happened? According to scholars, the short answer is that a rising population, coupled with a heavy reliance on wood for housing, canoe building, and statue transportation, decimated the forest (Brander and Taylor, 1998). The loss of the forest contributed to soil erosion, declining soil productivity, and, ultimately, diminished food production. How did the community react to the impending scarcity? Apparently, the social response was war among the remaining island factions and, ultimately, cannibalism.
We would like to believe not only that in the face of impending scarcity societies would react by changing behavior to adapt to the diminishing resource supplies, but also that this benign response would follow automatically from a recognition of the problem. We even have a clichĂ© to capture this sentiment: ânecessity is the mother of invention.â These stories do point out, however, that nothing is automatic about a problem-solving response. As we shall see as this book unfolds, sometimes societies not only fail to solve the problem but their reactions can actually intensify it.
Sources: Webster, D., Freter, A., & Golin, N. (2000). Copan: The Rise and Fall of an Ancient Maya Kingdom. Fort Worth, TX: Harcourt Brace Publishers; Brander, J. A., & Taylor, M. S. (1998). The simple economics of Easter Island: A RicardoâMalthus model of renewable resource use. The American Economic Review, 88(1), 119â138; Turner, B. L., & Sabloff, J. A. (2012). Classic period collapse of the central Maya lowlands: Insights about humanâenvironment relationships for sustainability. Proceedings of the National Academy of Sciences, 109(35), 13908â13914; Pringle, Heather. (2012). Climate change had political, human impact on ancient Maya. Science (November 9), 730â731.
Climate change also has an important moral dimension. Due to their more limited adaptation capabilities, many developing countries, which have produced relatively small amounts of greenhouse gases, are expected to be the hardest hit as the climate changes.
Dealing with climate change will require a coordinated international response. That is a significant challenge to a world system where the nation-state reigns supreme and international organizations are relatively weak.
Water Accessibility
Another class of threats is posed by the interaction of a rising demand for resources in the face of a finite supply. Water provides a particularly interesting example because it is so vital to life.
According to the United Nations, about 40 percent of the worldâs population lives in areas with moderate-to-high water stress. (âModerate stressâ is defined in the U.N. Assessment of Freshwater Resources as âhuman consumption of more than 20 percent of all accessible renewable freshwater resources,â whereas âsevere stressâ denotes consumption greater than 40 percent.) By 2025, it is estimated that about two-thirds of the worldâs populationâabout 5.5 billion peopleâwill live in areas facing either moderate or severe water stress.
This stress is not uniformly distributed around the globe. For example, in parts of the United States, Mexico, China, and India, groundwater is already being consumed faster than it is being replenished, and aquifer levels are steadily falling. Some rivers, such as the Colorado in the western United States and the Yellow in China, often run dry before they reach the sea. Formerly enormous bodies of water, such as the Aral Sea and Lake Chad, are now a fraction of their once-historic sizes. Glaciers that feed many Asian rivers are shrinking.
According to U.N. data, the continents most burdened by a lack of access to sufficient clean water are Africa and Asia. Up to 50 percent of Africaâs urban residents and 75 percent of Asians are estimated to lack adequate access to a safe water supply.
The availability of potable water is further limited by human activities that contaminate the remaining supplies. According to the United Nations, 90 percent of sewage and 70 percent of industrial waste in developing countries are discharged without treatment. And climate change is expected to intensify both the frequency and duration of droughts, simultaneously increasing the demand for water and reducing its supply.
Some arid areas have compensated for their lack of water by importing it via aqueducts from more richly endowed regions or by building large reservoirs. This solution can, however, promote conflict when the water transfer or the relocation of people living in the area to be flooded by the reservoir produces a backlash. Additionally, aqueducts and dams may be geologically vulnerable. For example, in California, many of the aqueducts cross or lie on known earthquake-prone fault lines (Reisner, 2003). The reservoir behind the Three Gorges Dam in China is so vast that the pressure and weight from the stored water have caused tremors and landslides.
Furthermore, climate change and water accessibility are interdependent problems. Example 1.2 explores both their relationship and why it matters.
EXAMPLE 1.2
Climate Change and Water Accessibility: How Are these Challenges Linked?
From a policy analysis point of view, whether these challenges are interdependent matters. If they are linked, their interactions must be considered in the design of any polices created to meet the challenges. Otherwise the r...