Greenhouse gases in the atmosphere absorb much of the long-wave energy emitted from the Earth’s surface, preventing it from immediately escaping from the Earth’s system. The greenhouse gases then re-emit this energy in all directions, warming the Earth’s surface and lower atmosphere.
The atmospheric concentration of greenhouse gases has increased over the past two centuries, largely due to human-generated carbon dioxide emissions from burning fossil fuels.
This increase has amplified the natural greenhouse effect by trapping more of the energy emitted by the Earth. This change causes Earth’s surface temperature to increase.
During the late 1980s one more term entered the lexicon, “global change.” This term encompassed many other kinds of change in addition to climate change. When it was approved in 1989, the U.S. climate research program was embedded as a theme area within the U.S. Global Change Research Program.
But global warming became the dominant popular term in June 1988, when NASA scientist James E. Hansen had testified to Congress about climate, specifically referring to global warming. He said: “global warming has reached a level such that we can ascribe with a high degree of confidence a cause and effect relationship between the greenhouse effect and the observed warming.”4 Hansen’s testimony was very widely reported in popular and business media, and after that popular use of the term global warming exploded. Global change never gained traction in either the scientific literature or the popular media.
But temperature change itself isn’t the most severe effect of changing climate. Changes to precipitation patterns and sea level are likely to have much greater human impact than the higher temperatures alone. For this reason, scientific research on climate change encompasses far more than surface temperature change. So “global climate change” is the more scientifically accurate term. Like the Intergovernmental Panel on Climate Change, we’ve chosen to emphasize global climate change on this website, and not global warming.