EXPLORING CLIMATE CHANGE
Name___ANSWER KEY______________
LESSON EXTENSION WORKSHEET- ADDITIONAL INDICATORS OF CLIMATE CHANGE
DATA SHEET 6
Note that the axes of this graph have a different orientation from the graphs in Data Sheets
1 and 2 in the original lesson. To correspond with the way sediment layers are arranged
in the ocean core, the vertical axis represents the age of the sediment in years, with the
youngest age (present) at the top. Unlike “normal” mathematical practice, the O-18
values on the horizontal axis decrease to the right, so be careful when reading this graph.
1) In general, what trend do you observe in O-18 values in the oldest part of the core (lower
white portion of the graph)? What does this suggest about atmospheric temperature during
this time period?
Relatively cooler temperatures, with some large fluctuations
2) What happens to O-18, and thus temperature, in the blue portion of the graph?
del O-18 decreases, thus temperature increases
3) What trend in O-18, and thus temperature, is apparent in the youngest part of the core
(upper white portion of the graph)?
Relatively high temperatures, smaller range of fluctuation than in the oldest part of the core
4) Do the O-18 data from the microfossils in this core support your observations from the ice
core data in Data Sheet 2? Explain.
Yes. They track the same pattern of the last major glacial period, then the end of that period, then the
most recent relatively “flat” pattern of elevated temperatures
DATA SHEET 7
1) At what time did the largest change in the calcium dust concentration take place? What
happened to the temperature at this time?
Very large decrease at 12000 - 12500 years ago, temperature had its largest increase at the same time
period
2) What is the general relationship between the calcium dust and the temperature graphs?
They are almost exact inverses of each other
3) What do you think causes this relationship?
When temperatures are low, much of global water is in ice caps & glaciers, thus sea level is lower and
large areas of the continental shelves are exposed to wind = lots of calcium dust. When temperatures
rise, increased melting of ice caps & glaciers, sea level rises & covers exposed continental shelves =
less calcium dust
4) What do you think was responsible for the large change in calcium dust concentration
observed in the first question?
End of the last glacial period, large rise in sea level, thus large decrease in calcium dust from
continental shelves
Exploring Climate Change
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