The buildup of greenhouse gases in the Earth's atmosphere, which has been increasing over the past 30 years, represents one of the more troubling human-caused impacts to the environment. The most worrisome effect of this buildup is climate change, marked by increasing global temperatures. Consider, for instance, that in the past decade, we registered the highest average global temperatures since reliable temperature recording.
Based on existing evidence, we must assume that further increases in concentrations of atmospheric carbon dioxide and other greenhouse gases will lead to further increases in global temperatures and cause destructive changes in weather patterns, trigger a rise in sea level, and damage ecosystems.
The sources that contend that global warming is, in fact, occurring are varied, but many experts seem to have arrived at similar conclusions. In a recent report for the Pew Center on Global Climate Change, for instance, the authors maintain that
technology has made it possible for human societies to produce $25 trillion of new goods and services annually. However, many advanced technologies utilize fossil fuels, which has led to the release of large amounts of carbon to the atmosphere. The scientific consensus is that these releases will cause the earth's climate to change. (1)
The most recent World Watch Institute report echoes that conclusion, pointing out that the Earth's ice cover is melting at higher rates than at any time since record keeping began and that the 1990s was the warmest decade on record. The United Nations Intergovernmental Panel on Climate Change believes that a reduction of 60 to 80 percent of greenhouse gas emissions is necessary to prevent this dangerous acceleration of global warming.
The United States is the largest energy consumer on the planet and, according to federal reports, emits almost a quarter of the world's greenhouse gases. The Annual Energy Review 1997, a document produced by the U.S. Department of Energy, notes that, while overall energy use increased, renewable energy consumption actually declined by 3 percent between 1996 and 1997 and accounted for only 8 percent of total U.S. energy consumption. This trend is troubling. Indeed, a national policy that promotes technical innovation and a shift from heavy reliance on fossil fuels to renewable energy is the key to moving the economy toward a healthier environment. Policies promoting an energy-efficiency revolution based on technologies that boost resource productivity are essential.
In their 1991 book Healing the Planet, ecologists Paul and Anne Ehrlich point out that, in terms of energy consumption, an average American causes 140 times the impact on the environment of an average Bangladeshi. (2) When this per capita value was combined with the United States' relatively large population, it resulted in an overall U.S. environmental impact--in terms of energy consumption--300 times that of Bangladesh. The authors conclude, therefore, that continuing population growth in rich nations poses the gravest threat to the world's life-support systems. In addition, given the large populations of most developing countries, economic growth in these countries will lead to enormous future environmental impacts, if energy-use patterns don't change. (3)
In 1990, atmospheric concentrations of carbon dioxide had risen about 25 percent higher than the historical average at the beginning of the Industrial Revolution, so presently we are looking at carbon dioxide levels in the atmosphere that are more than 30 percent greater than levels prior to the Industrial Revolution.
According to Robert Livernash and Eric Rodenburg of the World Resources Institute,
Emissions from the United States and the rest of the industrialized world are responsible for the bulk of excess carbon dioxide in the atmosphere today, but less-developed nations such as China and India, with rapidly expanding economies and populations, are expected to produce much of the growth in carbon dioxide emissions over the next several decades. …