Sulfate aerosol is particulate matter which consists of sulfur compounds formed by the interaction of sulfur dioxide and sulfur trioxide with other compounds in the atmosphere. Sulfate aerosols are injected into the atmosphere from the combustion of fossil fuels and the eruption of volcanoes like Mt. Pinatubo. Recent theory suggests that sulfate aerosols may lower the Earth's temperature by reflecting away solar radiation (called negative radiative forcing). Global climate models which incorporate the effects of sulfate aerosols more accurately predict global temperature variations.