as “an increase in the average temperature of the Earth’s atmosphere,” either by “human industry and agriculture” or by natural causes like the Earth has “experienced numerous” times “through its history.” * Some writers use the phrases “global warming” and “climate change” to mean temperature changes strictly caused by human activity.   Other writers use adjectives such as “man-made” and “anthropogenic” to distinguish between human and non-human causes.  (“Anthropogenic” means “of human origin,” and “AGW” stands for “anthropogenic global warming.”) * Just Facts’ Standards of Credibility require the use of “language that is precise and unambiguous.” Hence, when human causes are stated or implied, this research uses terms like “man-made” and “human-induced.” * The greenhouse effect is a warming effect caused by certain gases that retain heat from sunlight. Without such gases, the average surface temperature of the Earth would be below freezing, and as explained by the , “life, as we know it, would not exist.” The global warming debate is centered upon whether added greenhouse gases released by human activity will overheat the Earth and cause harmful effects. * Human activities currently release about 37 billion metric tons of CO2 per year, which equates to about 5% of natural CO2 emissions.