(Illustration by Robert Simmon, NASA GSFC)Īs air cools by rising into the atmosphere or moving toward the poles, moisture begins to condense and fall as precipitation. Scientists measure differences in oxygen isotope concentrations to reveal past climates.
The slighty greater mass of 18O-12.5 percent more than 16O-results in differentiation of the isotopes in the Earth’s atmosphere and hydrosphere.
The Oxygen-18 isotope has an extra two neutrons, for a total of 10 neutrons and 8 protons, compared to the 8 neutrons and 8 protons in a normal oxygen atom. At the same time, water vapor molecules containing the heavy variety of oxygen condense more readily. Water molecules containing light oxygen evaporate slightly more readily than water molecules containing a heavy oxygen atom. Water molecules are made up of two hydrogen atoms and one oxygen atom. What climate factors influence the ratio of oxygen isotopes in ocean water?Įvaporation and condensation are the two processes that most influence the ratio of heavy oxygen to light oxygen in the oceans. The standard scientists use for comparison is based on the ratio of oxygen isotopes in ocean water at a depth of 200-500 meters. By determining how the ratio of heavy and light oxygen in marine sediments, ice cores, or fossils is different from a universally accepted standard, scientists can learn something about climate changes that have occurred in the past. The ratio (relative amount) of these two types of oxygen in water changes with the climate. Understanding the Past to Predict the Future.“Light” oxygen-16, with 8 protons and 8 neutrons, is the most common isotope found in nature, followed by much lesser amounts of “heavy” oxygen-18, with 8 protons and 10 neutrons. All oxygen atoms have 8 protons, but the nucleus might contain 8, 9, or 10 neutrons. Like all elements, oxygen is made up of a nucleus of protons and neutrons, surrounded by a cloud of electrons. Oxygen comes in heavy and light varieties, or isotopes, which are useful for paleoclimate research. Oxygen is one of the most significant keys to deciphering past climates.
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