The predominant greenhouse gas produced by human use of fossil fuels is dioxidenitrous oxidewater vapormethane

The answer is carbon dioxide.  A greenhouse gas is a gas in the atmosphere that absorbs and emits radiant energy from the sun, thereby causing a 'greenhouse' effect. These gases are fundamental to life on Earth, as without them, the average temperature on Earth would be around −18 °C rather than  15 °C. However, a problem arises when there is too much greenhouse gas in the atmosphere, and the warming effect becomes too strong, leading to global warming.