An Introduction to Environmental Chemistry

been extracted, the time history of the composition of the atmosphere can be
established. The results from measurements made using this approach on an ice
core from western Antarctica are also shown in Fig. 7.2. It appears that in the
mid-18th century, before major industrialization (and agricultural development)

Global Change 241

CO

concentration (ppm) 2

1950 1960 1970 1980 1990 2000

Year

180

200

220

240

260

280

300

320

340

360

380

CO 2 Mauna Loa

CO 2 South Pole

O 2 Cape Grim

O 2 Barrow

O

(ppm) 2

1988 1992 1996

–40

–20

0

Fig. 7.1Direct measurements of atmospheric CO 2 and O 2 concentrations for northern
(Mauna Loa, Barrow) and southern (South Pole, Cape Grim) hemispheres, showing the
changing concentrations and seasonal cycles. After IPCC (2001). With permission of the
Intergovernmental Panel on Climate Change.

340

320

300

280

260

Compilation of early observations

Concentrations measured in ice cores

1700 1800 1900 2000

Year

CO

concentration (ppm) 2

Mauna

Loa

Fig. 7.2Atmospheric and ice core measurements of CO 2 in air. After Crane and Liss (1985),
reprinted with permission of New Scientist.