The Greenhouse Effect

The threat of global warming now forces a more detailed evaluation of the environment. It forces consideration of the sacrifices which must be made to ensure an acceptable quality of the environment for the future [4].

As an environmental problem, global warming must be considered on an entirely different scale from that of most other environmental issues: The effects of climate change are long-term, global in magnitude, and largely irreversible. Because of the enormity of the problem and the uncertainties involved—it may take decades to determine with absolute certainty that global warming is under way—the difficult questions faced today are how and when one should react.

Fossil-fuel burning and forestry and agricultural practices are responsible for most of the manmade contributions to the gases in the atmosphere that act like a greenhouse to raise the Earth’s temperature; hence the term “greenhouse effect.” Most of the processes that produce greenhouse gases are common everyday activities such as driving cars, generating electricity from fossil fuels, using fertilizers, and using wood-burning stoves. Because so many of these activities are so ingrained in society, reducing emissions could be a difficult task.

The search for solutions has begun. However, there is a growing concern that the costs of reducing emissions may be too high. But to put cost concerns in proper perspective, one must ask what kind of future one wants on this planet and how much does one value the environment and the cultural heritage that depends on it [4].

A consensus has emerged in the scientific community that global warming has occurred. Scientists are certain that the concentrations of carbon dioxide (C0₂) and other greenhouse gases in the atmosphere are increasing, and they generally agree that these gases will warm the Earth. Four questions remain to be answered:

• 1. How will the temperature rise?
• 2. When will the temperature rise?
• 3. Can the cause be attributed to man-made activities?
• 4. What are the potential greenhouses?

Recent estimates indicate that if the concentrations of these gases in the atmosphere continue to increase, the Earth’s average temperature could rise by as much as 1.5°C-4.5°C in the next century.

While this may not sound like a tremendous increase, one must keep in mind that during the last ice age 18,000 years ago, when glaciers covered much of North America, the Earth’s average temperature was only 5°C cooler than today.

Certainly, global cooperation is an important consideration when addressing global warming issues. No single country contributes more than a fraction of greenhouse gases, and only a concerted effort can reduce emissions. In the future, as developing nations grow and consume more energy, their share of greenhouse-gas emissions will steadily increase. It is important for other nations to offer technological assistance so that these developing nations can grow in an energy- efficient manner [4].

The sources of greenhouse gases are so numerous and diverse that no single source contributes more than a small fraction of total emissions. Similarly, no single country contributes more than a fraction of emissions.

Unlike other environmental problems that the EPA could address with the stroke of a regulation, potential climate change is a problem that needs innovative global solutions. Future trends of emissions will depend on a wide range of factors, from population and economic growth to technological development and policies to reduce emissions. Past trends show that all countries have been producing greenhouse gases at a growing rate, and many countries will continue to do so for years to come. Based on careful study of the sources and trends of greenhouse emissions around the globe, countries can begin implementing prudent measures for slowing down emission while increasing economic development.

The developed countries, currently the largest C0₂ emitters, will grow in population at approximately 1.0%-1.5% per year and are projected to emit 6.7 billion tons of carbon by the year 2025. Developed countries are likely to continue to emit more CO, per person than developing countries. For example, the average citizen living in the United States produced six times more CO, each year than the average citizen in a developing country. In developing countries, population and economic growth will lead to a substantial increase in CO, emissions to over 5 billion tons per year, despite anticipated improvements in efficiency of energy use.

Developing countries now contribute only a small fraction of greenhouse gases, but their share of emissions is expected to increase significantly in the next 25 years. Data show the share of CO, emissions from Asia (including China), Africa, Latin America, and the Middle East increasing from slightly over one-fourth of the global total in 1985 to nearly one-half the total by 2025. Technologies developed in more industrialized nations to use energy efficiently could help developing nations reduce emissions as they continue to develop, but channels to transfer this technology must be developed.

On a regional basis, energy use in Western European countries is projected to grow at a relatively slow rate because of low population growth and policies that are anticipated to be implemented over the next decade. Several countries, such as Norway, Sweden, and the Netherlands, have already adopted policies specifically designed to slow the growth rate of greenhouse-gas emissions. These measures include special taxes, energy-efficiency programs, and promotion of nuclear energy, natural gas, and renewable energy sources.

The case in Eastern Europe is quite different, largely because many of these countries are among the most energy intensive and most energy inefficient in the world. In Eastern Europe and the countries of the former Soviet Union, energy use and CO, emissions are projected to grow considerably over the next 35 years, but policies aimed at restructuring the economy and improving energy efficiency in Russia could have a significant impact. If these economies and those of Eastern Europe become more energy efficient and move from heavy industrial production to production of less energy-intensive consumer goods, they may be able to increase economic growth and enjoy the added benefit of reduced greenhouse-gas emissions.

In the coming years, the technical community must reevaluate how emissions are likely to change. But given this preliminary picture of the future, it is important to take the next step of assessing the specific technologies and policy measures that can reduce emissions now at low costs. Each country will have to examine its unique situation and determine appropriate responses. However, only by acting together will the global community slow the trend toward high emissions in the next century [3]. Additional details and methods for reducing the greenhouse effect are discussed in Part II [3].