Laboratory Manual for Introductory Geology 4e

FIGURE 18.7 Changes in temperature and in atmospheric carbon dioxide (CO 2
) and methane (CH 4
)
concentrations as measured in ice cores from Antarctica.
Temperatures are relative to the temperature in Antarctica today; negative values show times when they were cooler,
and positive values times when they were warmer, than the current temperature (0).
CH 4 (ppbv)
CO 2 (ppmv)
300
280
260
240
220
200
180
800
700
600
500
400
4
0
–4
–8
–12
Relative temperature
300
800 700 600 500 400 300 200 100 0
Thousands of years ago
EXERCISE 18.3
Assessing Human Contributions to Global Warming
Name:
Course:
Section:
Date:
The three curves in Figure 18.7 show that temperatures and concentrations of CO 2
and CH 4
have varied significantly over
the relatively recent geologic past.
(a) Is there any systematic relationship between increases in temperature and increases in CO 2
and CH 4
concentration?
What about between decreases in these values?
(b) What does your answer to question (a) suggest about the role of these gases in temperature changes?
(continued )
18.2 CHANGES IN THE EARTH SYSTEM
481