These changes are called Milankovitch cycles and account for some of the changes in past climates. Atmospheric Dust Volcanic eruptions and erosion from the earth's surface put dust and other fine particles of matter into the atmosphere. The presence of dust in the atmosphere prevents solar radiation from reaching the surface of the earth which causes the atmosphere to cool. This cooling, in turn, may inhibit vegetation growth which creates more exposed land susceptible to erosion. Ice core researchers look for the presence of calcium dust in the ice when they reconstruct ancient climates.
Calcium comes from limestone which is deposited in the ocean in large quantities.
During ice ages, sea level decreases as water is trapped in ice sheets around the globe. This exposes the continental shelves rich in calcium and prone to erosion. The dust is blown into the atmosphere and eventually falls to earth with rain or snow, preserving it as a record within the ice. Some gases accentuate the warming or cooling of the atmosphere. Those that warm the atmosphere are called greenhouse gases.