evidence: The terms "global warming" and "climate change" are sometimes used interchangeably, but global warming is just one of the ways in which climate is affected by rising concentrations of greenhouse gases. "Global warming" describes the recent rise in the global average temperature near the earth's surface, which is caused mostly by increasing concentrations of greenhouse gases (such as carbon dioxide and methane) in the atmosphere from human activities such as burning fossil fuels for energy. [...] Yes. Climate scientists overwhelmingly agree that people are contributing significantly to today’s climate change, primarily by releasing excess greenhouse gases into the atmosphere from activities such as burning fossil fuels for energy, cultivating crops, raising livestock, and clearing forests. The Intergovernmental Panel on Climate Change's Sixth Assessment Report, which represents the work of hundreds of leading experts in climate science, states that "it is unequivocal that human influence has warmed the atmosphere, ocean and land. Widespread and rapid changes in the atmosphere, ocean, cryosphere, and biosphere have occurred." [...] The earth does go through natural cycles of warming and cooling caused by factors such as changes in the sun or volcanic activity. For example, there were times in the distant past when the earth was warmer than it is now. However, natural variations in climate do not explain today’s climate change. Most of the warming since 1950 has been caused by human emissions of greenhouse gases that come from a variety of activities, including burning fossil fuels.