Compare the current interglacial ( 0 to 10,000 years ago) to previous interglacials with respect to temperature and duration (length of time). Note that there is more detail to the current interglacial - this represents a difference in sample resolution rather than an actual difference. There are more samples per unit of time closer to the surface because the ice compresses with depth. In other words, a given thickness of ice corresponds to less time near the surface of the ice sheet, and more time near the base of the ice sheet. That's why there is more detail to the graph closer to time = 0 (the present). The small details are lost with depth as each ice sample represents a longer period of time. 6. Were previous interglacials warmer or colder than the current interglacial, which has a mean annual temperature at Vostok of 5 5 C ? Explain your answer. Hint: make the temperature graph active by clicking on it. Move the mouse over the interglacials to find the temperature at their highest point. 7. How does the duration (length) of the current interglacial compare to previous interglacials? Explain your answer. Relationship of Greenhouse Gas Concentrations to Temperature Changes Refer to the graphs of carbon dioxide ( CO 2 ) and methane ( CH 4 ) versus age (time) to answer the following questions. Carbon dioxide concentrations are in parts-per-million by volume (ppmv), methane concentrations are in parts-per-billion by volume (ppbv). A part per million of carbon dioxide literally means that there is one molecule of carbon dioxide per every million molecules of air. One part per billion is 1/1000 of one part per million - other words 1000 ppbv = 1 ppmv . 8. Compare the plots of carbon dioxide and methane to your graph of temperature changes at Vostok. Describe how carbon dioxide and methane concentrations change in relation to temperature. 9. Discuss, in general terms, how CO 2 and CH 4 concentrations during glacial periods compare to those during interglacial periods. 10. Note the timing of the four major warming events representing deglaciations (the end of an ice age and the beginning of an interglacial climate). Then look at how CO 2 and CH 4 change during the same time. Can you tell which changes first, temperature or greenhouse gas ( CO 2 , CH 4 ) concentrations? Does it matter? Explain your answer. Hint: Can you find any examples of time periods when temperature changed without greenhouse gas concentrations also changing? Or any time periods when greenhouse gas concentrations changed without temperature also changing? Use the graphs of carbon dioxide ( CO 2 ) vs. temperature and methane ( CH 4 ) vs. temperature to answer the following questions. Unlike the previous graphs, which plotted the variables (temperature, CO 2 , CH 4 ) versus time (age), these graphs are scatterplots that graph the variables versus each other CO 2 versus temperature and methane versus temperature. This allows us to directly examine the relationships between vari.

1. Compare the current interglacial ( 0 to 10,000 years ago) to previous interglacials with respect to
temperature and duration (length of time). Note that there is more detail to the current
interglacial - this represents a difference in sample resolution rather than an actual difference.
There are more samples per unit of time closer to the surface because the ice compresses with
depth. In other words, a given thickness of ice corresponds to less time near the surface of the ice
sheet, and more time near the base of the ice sheet. That's why there is more detail to the graph
closer to time = 0 (the present). The small details are lost with depth as each ice sample
represents a longer period of time. 6. Were previous interglacials warmer or colder than the
current interglacial, which has a mean annual temperature at Vostok of 5 5 C ? Explain your
answer. Hint: make the temperature graph active by clicking on it. Move the mouse over the
interglacials to find the temperature at their highest point. 7. How does the duration (length) of
the current interglacial compare to previous interglacials? Explain your answer. Relationship of
Greenhouse Gas Concentrations to Temperature Changes Refer to the graphs of carbon dioxide (
CO 2 ) and methane ( CH 4 ) versus age (time) to answer the following questions. Carbon
dioxide concentrations are in parts-per-million by volume (ppmv), methane concentrations are in
parts-per-billion by volume (ppbv). A part per million of carbon dioxide literally means that
there is one molecule of carbon dioxide per every million molecules of air. One part per billion is
1/1000 of one part per million - other words 1000 ppbv = 1 ppmv . 8. Compare the plots of
carbon dioxide and methane to your graph of temperature changes at Vostok. Describe how
carbon dioxide and methane concentrations change in relation to temperature. 9. Discuss, in
general terms, how CO 2 and CH 4 concentrations during glacial periods compare to those
during interglacial periods. 10. Note the timing of the four major warming events representing
deglaciations (the end of an ice age and the beginning of an interglacial climate). Then look at
how CO 2 and CH 4 change during the same time. Can you tell which changes first, temperature
or greenhouse gas ( CO 2 , CH 4 ) concentrations? Does it matter? Explain your answer. Hint:
Can you find any examples of time periods when temperature changed without greenhouse gas
concentrations also changing? Or any time periods when greenhouse gas concentrations changed
without temperature also changing? Use the graphs of carbon dioxide ( CO 2 ) vs. temperature
and methane ( CH 4 ) vs. temperature to answer the following questions. Unlike the previous
graphs, which plotted the variables (temperature, CO 2 , CH 4 ) versus time (age), these graphs
are scatterplots that graph the variables versus each other CO 2 versus temperature and methane
versus temperature. This allows us to directly examine the relationships between variables. These
graphs illustrate what you should have already noticed: there is, in the past, a strong relationship
between temperature and the concentrations of the greenhouse gases carbon dioxide and
methane. Each of these plots has a linear trendline with an equation and R 2 value, or correlation
that describes this relationship between greenhouse gases and temperature mathematically. An r
2 value of 1 indicates a perfect 1 : 1 relationship. An r 2 value of 0.5 is generally considered a
strong relationship. An r 2 value less than 0.3 is often considered weak. 11. Which is better
correlated (has a higher r 2 value) with temperature, CO 2 or CH ? Explain why. Hint: how do
atmospheric CO 2 concentrations compare to methane concentrations? 12. Use the past
relationship between CO 2 and temperature to predict the expected average temperature at
Vostok now given the recent increase in the amount of CO 2 in the atmosphere. To do this, plug
in today's CO 2 concentration, 420 ppmv , in for x in the equation given by the scatterplot of CO
2 vs. temperature and solve for y (temperature). Report your answer below and show your work.
13. Do you think this a good estimate for today's temperature at Vostok? Explain why or why
not. Hint: We have considered only the effects of CO 2 on temperature. Do you think this makes

2. for an accurate prediction? Are there other factors that might influence temperature? What other
factors in the climate system might have an important affect on temperature? 14. The current
mean annual temperature at Vostok is around 5 5 C . However, we predict a much warmer
temperature should exist at Vostok today, given the observed relationship between CO 2 and
temperature that existed in the past. Brainstorm and list possible reasons for this apparent
discrepancy, such as other factors that affect temperature besides CO 2 , or reasons why warming
may lag behind the CO 2 increase. How Does Recent Warming Compare to the Warming at the
End of the Ice Age? Let's take a closer look at the changes in temperature and greenhouse gas
concentrations that occurred at the end of the last lce Age. Return to the graph of temperature
versus age (time). Right click on the X axis and choose Format Axis. A dialog box appears. Set
maximum value to 25,000 , major unit to 5000 , and minor unit to 1000 . Click close. The graph
is now zoomed in on the period 0 25 , 000 years ago- which encompasses the time from the last
glacial maximum (the coldest part of the most recent Ice Age) to the present day. Do the same
for the graphs of CO 2 and CH 4 versus age and answer the following questions. 15. What was
the average CO 2 and CH 4 concentration during the last glacial maximum ( 20 , 000 25 , 000 )
years ago? Hint: use Excel to calculate the average over the given time period by entering this
formula in any blank cell to calculate the average over an appropriate range of cells: -
average(cell1:cell2) - for example, the average CO 2 concentration from 20 , 000 25 , 000 years
ago is given by entering the formula = average(b20:b24) into any blank cell on the GHG vs
Temp tab. CO 2 : 16. The current interglacial is called the Holocene and began 11 , 000 years
ago. What are the Holocene averages for these gases in the Vostok ice core ( 0 to 11,000 years
ago)? Note that the Vostok data ends 2300 years ago because it takes time for the very slow
spow accumulation rate at Vostok to bury snowfall to a sufficient depth for densification to seal
the bubbles and trap a sample of the atmosphere, so your average for the Holocene will only
cover the time period for which we have data from the Vostok ice core and exclude any recent
changes due to industry and agriculture. CO 2 CH 4 17. What is the difference in CO 2 and CH 4
between the last glacial maximum and the Holocene average? CO 2 CH 4 18. Current
concentrations of CO 2 and CH 4 are 420 ppmv and 1895 ppbv, respectively. What is the
difference between the average Holocene values and today's concentrations? CO 2 : CH 4 19.
How much warming (in degrees) occurred at Vostok between the last glacial maximum and the
Holocene? Use the graph of temperature changes over time to answer this question. 20. How do
the human-caused increases in CO 2 and CH 4 since the industrial revolution compare to the
increases at the end of the last Ice Age? What does this suggest about the amount of warming we
might expect over the coming decades and centuries, given the increase in CO 2 and CH 4 that
has already occurred?