Global climate change. Global climate change is a significant alteration from one climatic condition to another, beyond the usual alterations in various climates throughout the globe, as the result of human activities. The greatest of these is fossil fuel combustion, which traps greenhouse gases in the atmosphere that cause gradual changes in Earth’s temperatures over hundreds of years. The term “global warming†may also be used but refers more specifically to temperature, whereas global climate change encompasses the broader changes associated with elevated greenhouse gas levels, such as dryer deserts, increased numbers of hurricanes, and warmer oceans. Learn more about global climate change.