Oxygen

Figure 12. Oxygen isotope records recorded in the layers of snow of the Greenland ice sheet, shown here as the departure of the oxygen-18 isotope [d18O in parts per thousand (o/oo)] versus time (in thousands of years before present). The right-hand scale shows deviations from mean Holocene temperatures assuming that the d18O deviation from the mean Holocene d18O of 34.8 o/oo is caused by local temperature changes with a d18O-temperature coefficient of 0.63 o/oo per°C [Source: P. Grootes and M. Stuiver, University of Washington; and Greenland Ice Sheet Project 2 (GISP2), University of New Hampshire].