The ratio of oxygen and hydrogen isotopes in water molecules. Both elements have two abundant and stable isotopes: one heavier and one lighter. The quotient o

The ratio of oxygen and hydrogen isotopes in water molecules. Both elements have two abundant and stable isotopes: one heavier and one lighter. The quotient of the heavier isotopes in land ice is a linear function of the temperature, because it takes more energy to evaporate the heavier isotopes from icean water.