Ice core data - Ice Ages and Interglacials: Measurements, Interpretation, and Models - page 138

Figure 4.4. Greenland temperature history from GRIP over 20,000 years (smoothed data).
Figure 4.5. GISP2 ice core results taken at Greenland summit over 40,000 years (adapted from
http://www.mos.org/soti/icecore/studies.html ).