Why is methane thought to have been an important greenhouse gas during the Archean Era?
What will be an ideal response?
Methane is thought to be important for a number of reasons. First, methanogens are thought to have been among the first forms of life on Earth, so there should have been a significant biogenic flux of CH4 into the atmosphere. Additionally, paleosol data place an upper limit on atmospheric CO2 concentrations that is too low to allow for liquid surface water given a strict CO2-H2O greenhouse. Thus, another greenhouse gas is needed to permit the presence of liquid water, and CH4 is one of the more likely candidates for this. The other likely candidate, NH3, is rapidly photolyzed and should not have had a long enough lifetime to be an effective greenhouse gas. (Note: The paleosol data are contentious, and so there is not widespread agreement on an upper limit for CO2. This remains a topic for further research.)
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Which of the following segments best illustrates the end of a midlatitude cyclones occlusion process?
A) F-E
B) D-C
C) B-A
The geological study of rocks around a previously active volcano ____
a. ?is of scientific interest but does not aid eruption prediction b. ?is complicated by the effects of erosion c. ?concentrates on the study of tuff layers, with little other useful information d. ?can detect chemical changes in rocks caused by carbon dioxide emissions e. ?can only identify sites of lava flows
Satellite images and remote sensing techniques are commonly used to monitor tropical rain forest clearing
Indicate whether the statement is true or false
Which of the following best describes the Mercalli earthquake scale?
A. Is a quantitative measure of earthquake intensity. B. Is a qualitative measure of earthquake intensity. C. Measures the amplitude of the strongest S-wave. D. Measures the amplitude of the strongest P-wave. E. Measures the amplitude of the strongest surface wave.