Figure 6. Ice-core record from Vostok, Antarctica provides a record of climate change over the past 500,000 years. Shown at top is the deuterium record (a proxy for temperature) for the past
160,000 years, which contains the last glacial-interglacial cycle. The climate transitions are not as
abrupt in central portions of Antarctica as they are in more coastal locations. The atmospheric CO2
record clearly shows how human activity has increased both the concentration of CO2 and the rate
of increase of CO2 to unprecedented levels. (Deuterium data from J. Jouzel, Laboratoire de
Modélisation du Climat et de l’Environnement, France. CO2 data, from direct observations and
three different ice cores, come from C. Keeling, Scripp’s Institution of Oceanography; A.
Indermuhle and A. Neftal, University of Bern; and J. Barnola et al., Laboratoire de Glaciologie et
