greenhouse gases to varying extents. In most societies the burning of fossil fuels for electricity and transportation is a major contributor.
Since releases of greenhouse gases are connected to most economic activity, significant reductions in their emission may affect the economic competitiveness of individuals, firms, and nations. Avoiding additional greenhouse warming may be costly, it may create economic winners and losers, and it may alter trade balances.
The world's population today is 5.3 billion, and it is expected to continue to grow at about 1.7 percent per year at current rates of fertility. Figure 2.1 shows historical population growth and an estimate for 2000. This increasing population is one of the major factors affecting trends in greenhouse gas emissions. More people create greater demand for food, energy, clothing, and shelter. Producing such products emits greenhouse gases.
Economic growth also produces more greenhouse gas emissions. If population grows with constant per capita income, more resources are used for food, clothing, and shelter. If per capita income grows in a constant population, the demand for goods also grows, particularly for health and education services, transportation, and housing. Most nations in the world have policies to reduce population growth rates, but all nations seek to achieve rapid growth in per capita income. The reduction of greenhouse gas emissions is well served by the first objective (reducing population growth) but, depending on the means used, can be in conflict with the second (growth in per capita income).
The detailed links between population growth and greenhouse gas emissions are complex and not well understood. The developing countries that have reduced their population growth rates within the last 30 years did so only after rapidly increasing their standards of living. This often was accompanied by environmental degradation. Perhaps it will be possible to rapidly raise living standards without resulting in traditional patterns of pollution. Unfortunately, there are few examples to guide us. What is needed is a breakthrough in strategies for development, especially with respect to energy supply and demand. Developing countries experiencing rapid economic growth will need effective mitigation programs if they are to avoid substantial increases in their greenhouse gas emissions. Implementing new strategies will require funds that will probably be scarce if populations grow rapidly. Nevertheless, at any given per capita rate of greenhouse gas emissions, a smaller population means fewer emissions, as well as less stress on the environment in general.