Geology Long Term Climate Change Lab Assignment:
1. How do the two signals compare? Identify those areas where they match and where they fail to match on the provided 150,000-year CH4 record.
2. How many individual peaks did you count in the CH4 record?
3. Divide the 150,000 years of record by the number of peaks you counted to get a good estimation of the length of the major cycles in this record (the average number of years from peak to peak).
4. Try this peak-counting exercise again, using the entire 350,000-year record of methane. How many peaks did you get?
5. Divide 350,000 years of record by the number of peaks you counted to calculate the average peak-to-peak spacing Hint: your answer should have the units: years/cycle.
6. To which of the three orbital cycles (23,000; 41,000; and 100,000 years) is the CH4 record closest?
7. How do the two signals compare? Is it considered a ‘good match’? Comment on the quality of the match you get compared to the observations you made when you answered question 9.
8. How does the 23,000-year precession signal compare to the 150,000-year record of CO2? Is it a ‘good match’?
9. How does the 41,000-year tilt signal compare to the 150,000-year record of CO2? Is it a ‘good match’?
10. How many significantly large CO2 peaks (those that change by 80 parts per million or more) do you see in the 350,000 years of record?
11. As you did earlier, divide the number of peaks you have counted into the 350,000-year length of record. What is the average cycle length for these large-scale oscillations in the CO2 record?
12. To which of the three orbital cycles (23,000; 41,000; and 100,000 years) is the CO2 record closest?
13. Is this a ‘good match’?
14. What aspect of the basic shape of the two signals keeps the match from being better, even though the individual cycles are close in overall length?
15. How similar or dissimilar do the CO2 record and the “net glaciation” signal look to you? Do both of them have a cycle near 100,000 years? Do the CO2 decreases and glacial coolings occur at roughly the same rate as the CO2 increases and glacial warmings?
16. The graph above shows methane concentrations for the past three to four hundred years. Indicate the approximate range of methane concentrations over this period of time. Provide both a low concentration in ppb and a High concentration in ppb.
17. How well do the CH4 values of the last three to four hundred years fit within the natural range of past values recorded in the Vostok core?
a) The recent values are mostly lower than the values during the last 350,000 years.
b) The recent values are mostly within the natural range of variability.
c) The recent values are mostly higher than the values during the last 350,000 years.
18. The graph above shows carbon dioxide concentrations for the at least the past three to four hundred years. Indicate the approximate range of carbon dioxide concentration over this period of time. Give your answer in low concentration ppm and high concentration ppm.
19. How well do the CO2 values of the last three to four hundred years fit within the natural range of past values recorded in the Vostok core?
a) The recent values are mostly lower than the values during the last 350,000 years.
b) The recent values are mostly within the natural range of variability.
c) The recent values are mostly higher than the values during the last 350,000 years.
20. Choose one statement from Menu A and one statement from Menu B below. Choose the statements that most closely represent your views on greenhouse gases and long-term climate change:
The recent changes in CH4 and CO2 concentrations are a result of:
Menu A:
• predominately human activity
• predominately natural variation
• a combination of human activity and natural variation
Menu B:
• WILL affect long-term climate.
• WILL NOT affect long-term climate.
• MAY affect long-term climate.
Briefly explain/Defend the statements that you have chosen above.