How Do Ice Cores Reveal Information About Our Past?
Information about temperatures can be determined by examining the type of water in the ice. Water can exist as normal water, or it can contain the isotopes, heavy oxygen (18O) or heavy hydrogen (2H). Normal water, because its vapor pressure differs and it has lighter mass, separates from heavy water (water that contains one of the isotopes of oxygen or hydrogen) through processes of evaporation or snow formation. This separating is called fractionation. Taking data from current snowfalls, an equation of temperature can be derived looking at this amount of fractionation. So scientists look at the fractionation that occurred in the snowfalls that created the ice in the past and they can determine what the temperature was when the snow fell! Pretty neat, huh! This creates a record of the temperatures through the years.
