In this module, the importance of ice cores and an application of the oxygen isotopic ratio is discussed. Request: Present a brief essay answer (about 250-300 words) describing how the isotopic ratio is likely to change in the Polar Ice caps, precipitation, and the global ocean during the onset of the next glacial period and a subsequent return to an interglacial period. Brief essays should have an introductory and concluding statement. Please use where appropriate in text citations and references and use the Harvard Reference Guide.