Atmosphere and Climate Change

Many climate scientists agree that the increase of heat-trapping greenhouse gases in the atmosphere is already influencing the world's climate, although separating out the human influence in recent extreme weather events remains difficult. There is no doubt, however, that the human impact on climate is growing steadily. The combustion of fossil fuels such as oil, coal and natural gas is the dominant source of greenhouse gas emissions. And most of the activities associated with release of the gases–transportation, power generation, heating, cooling, cooking and most production processes–are basic and pervasive. In effect, we are gambling with one of the planet's fundamental life support systems, and the stakes of this gamble are increasing with time.

A warming climate would alter patterns of rain and wind in unpredictable ways. More heat would lead to more rapid evaporation of water from land and oceans, and thus to greater precipitation alternating with more intense drought. Added heat would also energize weather systems that create hazardous storms. Warmer oceans would expand in volume and encroach onto inhabited coasts, while shifting climate regimes would threaten agriculture and ecosystems‹and quite possibly human settlements‹in the United States and elsewhere.

Few specialists doubt that human activities will change the world's climate noticeably, and many scientists believe the human impact is already evident. Responding to the dominant scientific view, the U.S. government has announced it will seek a binding international agreement to reduce the release of greenhouse gases into the atmosphere.1 Just to keep emissions constant in any given country would require each individual on average to continually reduce his or her use of fossil fuels by an amount inversely proportional to that country's rate of population growth. With economic growth and associated consumption patterns (especially the growing popularity of automobiles in both wealthy and less wealthy countries), however, per capita use of fossil fuels is increasing, not decreasing. This increase is amplified as each year the world has more inhabitants.

Who can argue against people everywhere aspiring to enjoy a standard of living comparable to that of the United States? Yet with just 5 percent of the world's population the United States accounts for 22 percent of the world's fossil fuel consumption. A planet full of American-style consumers would multiply the world¹s carbon dioxide emissions by nearly five times current levels.2 To stabilize atmospheric concentrations of the greenhouse gas carbon dioxide at anything close to current levels, however, humanity would need to reduce these emissions by 60 percent or more from current global levels through sharp reductions in the combustion of fossil fuel.3 To reach such a goal, the average person would need to use no more of these carbon-emitting fuels than did the average person of the first half of the 20th century–before widespread automobile ownership, electrification and overall economic development.4 As world population grows and per capita natural resource consumption increases, the reductions in greenhouse gas emissions needed to stabilize the atmosphere and climate will become increasingly difficult to achieve.