Watch Your Step: Understanding the Impact of Your Personal Consumption on the Environment by Philip Camill Department of Biology Carleton College Part I. Future Imperfect? Imagine you could see into the future and watch the next 100 years unfold. Let's say that human populations, resource consumption, and waste continue to grow according to a business-as-usual scenario with few changes in policy or lifestyles to curb these trends. Would you notice a point when Earth is no longer able to sustain human population growth, resource consumption, and pollution? Have we already reached this point? How could you tell? What does it take to sustain life on Earth? The issue of sustainability is a challenging one, and the long-term survival of life as we know it may depend on how we define sustainability as well as the policies and lifestyle changes necessary to achieve it (Brundtland 1987). Understanding how the Earth system sustains human life is a fascinating problem. Interestingly, space travel provided an early impetus for creating artificial life-support systems based on ecological principles similar to those of Earth's biosphere (Corey and Wheeler 1992, Galston 1992, Schwartzkopf 1992). The goal was to develop a self-sustaining biosphere in miniature that could extend the duration of space flights or allow humans to colonize another planet like Mars. In 1984, a company called Space Biospheres Ventures began the most ambitious example of this kind of research—a project called Biosphere 2—to replicate a self-sustaining biosphere like Earth's (a.k.a. Biosphere 1). Columbia University Biosphere 2 Center has become an important experiment for understanding the life-support functions of the biosphere. Simply put, do we know enough about how the Earth's biosphere sustains human life to be able to replicate it or preserve it? Fig. 3. Picture of Fig. 1. Fig. 2. Ecosystems in the ocean Biosphere 2 Lab Biosphere 2 Lab ecosystem All images of Biosphere 2 are the property of Columbia University Biosphere 2 Center and are used with permission. 2 Between 1984 and 1991, Columbia University Biosphere 2 Center was built in Oracle, Arizona, at a cost of over $200 million (Nelson et al. 1993, Cohen and Tilman 1996) (see Fig. 1). The structure was not just a building where people could attempt to live sustainably—it was much bolder. Biosphere 2 was a giant glass chamber sealed off from the atmosphere that contained living ecosystems including a tropical rainforest, ocean, savannah, desert, marsh, and agricultural landscape (see Figs. 2 and 3). It enclosed 13,000m2 of land and a total volume of 204,000m3 (Cohen and Tilman 1996). The original test of Biosphere 2 attempted to determine if these ecosystems could support the lives of eight people in perpetuity. Their only source of food was what they could grow in the agricultural sector. Their only source of oxygen was from plants and algae in the terrestrial and oceanic ecosystems. In 1991, the eight researchers were sealed in Biosphere 2, and the world watched. In this case study, you will examine the issue of sustainability of humans on Earth using the concept of the "ecological footprint" (Wackernagel and Rees 1996). This is a powerful method for understanding sustainability and how to quantify it. As we will see, Biosphere 2 provides a good example of the ecological footprint concept because it represents a specific amount of land area (footprint size) and land use types thought sufficient to sustain the lives of eight people. We will see the outcome of the Biosphere 2 experiment at the end of the case. Questions: Imagine you are a team of senior research scientists at the initial planning phase of Biosphere 2. What kinds of specific conditions would be needed in Biosphere 2 to make it possible to sustain eight people for the rest of their lives? You might consider the following questions and sources of information: z "Ecological services" as described in the article Ecosystem services: Benefits supplied to human societies by natural ecosystems by Daily et al. (1997). z Should the eight researchers' diets be vegetarian or meat-based? What difference would this make? z Are the ecosystem types shown in Fig. 2 above sufficient to sustain people? z Should animals be included in Biosphere 2? If so, what kinds? z How might driving a car in Biosphere 2 affect the sustainability of the eight people? Part II. A Delicate Balance On October 12, 1999, Secretary-General of the United Nations, Kofi Annan, welcomed Adnan Nevic of Sarajevo, Kosovo, into the world, marking the birth of the six billionth living human. The event rejuvenated long-standing debate about how many people the Earth can support before exhausting the supply of natural resources and a clean environment. Most current estimates project a human carrying capacity, or the number of people that the Earth can support, at around 12 billion, occurring sometime within the next century (Cohen 1995). The difficulty of determining the uppermost limit of human population is that the human carrying capacity changes through time and will likely rise to some extent with increasing population. Former President George H.W. Bush argued that "Every human being represents hands to work and not just another mouth to feed" (Bush 1991). This suggests that more people can acquire more resources to sustain larger populations, such as building irrigation canals to grow more food or building more housing. More people may lead to greater ingenuity and technical innovation, such as medical advances and genetically engineered crops. However, others have pointed out that this view does not specify the cultural, environmental, and economic resources available to make additional hands productive and, 3 therefore, does not specify by how much the additional hands can increase human carrying capacity (Cohen 1995). For example, there is no advantage to more people in drought-stricken countries where irrigation canals are useless. There is no advantage to more people if raw materials, such as lumber, are not available to build homes. The advantage of additional scientists may be limited if research funding declines. Potential limits to human population size depend critically on the relative balance between the rate of consumption of natural resources and the production of waste versus the rate at which natural resources and services are provided by the planet. Joel Cohen of Rockefeller University argues that "To believe that no ceiling to population size or carrying capacity is imminent entails believing that nothing in the near future will stop people from increasing Earth's ability to satisfy their wants by more than, or at least as much as, they consume" (Cohen 1995). He emphasizes this point poignantly: "How many people the earth supports depends on how many people will wear cotton and how many polyester; on how many will eat meat and how many bean sprouts; on how many will want parks and how many will want parking lots. These choices will change in time and so will the number of people the Earth can support" (Cohen 1995). Not only does human sustainability on Earth depend on population size, it also depends on rates of material consumption and waste production by the population. Although human population growth rates are often highest in developing nations, income and material consumption are often more than an order of magnitude greater in wealthy industrialized nations, such as the United States, Japan, Canada, France, Germany, and England (see Table 1). 4 Table 1. Population growth rates and doubling times of selected countries for year 2001. Data Sources: Population Reference Bureau and World Bank. Per-capita Annual Population Population Doubling Country Continent/Region purchasing power Increase (%) Time (yr)* (1999 $) Palestinian Middle East 3.7 % 19 NA Territory Oman Middle East 3.5 % 19 NA Solomon Islands Oceana 3.4 % 20 2,050 Yemen Middle East 3.3 % 21 730 Chad Africa 3.3 % 21 840 Maldives Asia 3.2 % 22 4880 Liberia Africa 3.1 % 23 NA Demo. Rep. Africa 3.1 % 23 590 Congo Bhutan Asia 3.1 % 23 1,260 Gambia Africa 3 % 23 1,550 Mali Africa 3 % 23 740 Saudi Arabia Middle East 2.9 % 24 11,050 Guatemala Central America 2.9 % 24 3,630 Pakistan Asia 2.8 % 25 1,860 Honduras Central America 2.8 % 25 2,270 Paraguay South America 2.7 % 26 4,380 China Asia 0.9 % 77 3,550 United States North America 0.6 % 116 31,910 France Western Europe 0.4 % 174 23,020 Canada North America 0.3 % 231 25,440 Japan Asia 0.2 % 347 25,170 United Kingdom Western Europe 0.1 % 693 22,220 Italy Western Europe 0 % — 22,000 Greece Western Europe 0 % — 15,800 Poland Eastern Europe 0 % — 8,390 Sweden Western Europe 0 % — 22,150 Germany Western Europe -0.1 % — 23,510 Czech Republic Eastern Europe -0.2 % — 12,840 Latvia Eastern Europe -0.6 % — 6,220 Russia Eastern Europe -0.7 % — 6,990 Ukraine Eastern Europe -0.7 % — 3,360 * Population doubling time is calculated as t = ln(2)/ln(R), where ln = natural logarithm and R is popuation growth rate, which is equivalent to 1 + the fractional annual population increase. 5 To the extent that material consumption drives energy use, resource extraction, pollution, climate change, and landfill buildup, this means that industrialized nations have a larger per-capita impact on the environment (Brown et al. 1993, Herendeen 1998). The United States, by virtue of its massive per- capita consumption of natural resources and energy and its generation of CO2 and waste, could be considered the most overpopulated country in the world in terms of environmental impact (Cohen 1995, Gardner and Sampat 1999).