EXERCISE 1: ICE CORES
Envs4000: Cold regions and Environmental Change
Dr. Hester Jiskoot Fall 2010
Purpose of this exercise is to become familiar with interpreting ice core data in excel, and using background research
using your lecture notes and literature on the internet to interpret some of the patterns in the data.
This exercise uses two ice core datasets. Eclipse_volcanics.xls and Greenland_Antarctica_methane.xls.
First, retrieve both excel files from the class webpage: http://classes.uleth.ca/201003/envs4000n/, as well as the
additional information.
For your report:
 Plot the requested graphs and answer the questions in Parts A and B below.
 Answer your questions in complete sentences and write in clear English.
 You can submit the report as a group of maximum two students. Write both your names at the top of the report.
 Email Tayler Hamilton (the TA for this class) (tayler.hamilton@uleth.ca) the report by Tuesday 12 October 5pm.
Part A: Volcanics from a Canadian ice core (20 points)
1. Open the file Eclipse_volcanics.xls and download Eclipse_Icefield_1996_CoreAccumulation.doc as background
information. Volcanic Sulfate (SO4) injected into the stratosphere is slowly converted to sulfuric acid aerosol and can
remain aloft for as much as 3 years after an eruption. Plot Sulfate as a Scatterplot (symbols with connector lines and
calendar year on the x-axis). Label your axes (don’t forget the units: see the .doc file) and adjust the scale to a logical
one. What is the range in sulphate measurements at this site? (10 pt)
2. The two major volcanic eruptions in the last century were of Mt Novarupta (aka neighbouring Mt Katmai) (1912) and
Mt Pinatubo (1991). What are the exact signals in the sulfate record at Eclipse Icefield? Do these occur in the year of
eruption of some years later? Why would these signals have such different magnitudes and time lags? (10 pt)
Part B: Methane (50 points)
1. What are the possible sources and source regions of methane in Greenland and Antarctic Ice cores? Separate your
answer in anthropogenic and non-anthropogenic sources. (5 pt)
2. What are the depth and maximum ages of the respective ice cores? Note that ages are expressed in kiloyears before
1950 (years x 1000 BP). Is the longest ice core also the oldest? If not, why not? (5 pt)
3. Plot Gas time (x-axis) and Methane concentration (y-axis) of both GISP2 and Taylor Dome in one plot as a scatterplot
with line. Label you axes and adjust the scale to a logical one. See Fig 1 for an example. (15 pt)
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Methane concentration (ppb)
Methane (ppb) GISP2
Methane (ppb)Taylor Dome
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300
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Gas Age (ky)
Fig 1: Example methane graph
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EXERCISE 1: ICE CORES
Envs4000: Cold regions and Environmental Change
Dr. Hester Jiskoot Fall 2010
4. In which period (give years) does the minimum methane concentration occur in both ice cores? What is this period
usually referred to as? Why would the methane concentration worldwide be at its minimum in this period? (5pt)
5. Is there a systematic difference between the methane concentrations in the ice cores? Describe the general
difference and explain why (think about sources/sinks, mixing of methane in the atmosphere, and hemispheric
differences in climate). Calculate from your data how much the maximum difference is in the Younger Dryas time
period, and explain what the cause of this maximum difference could be during this specific period. (10 pt)
6. What is the present methane concentration according to the IPCC 2007 report? How much higher is this than the
maximum since the last interglacial (125000 yr BP)? What are the main anthropogenic sources of methane and what
is predicted for the methane concentration in the near future (a century or so)? (10 pt)
Additional reading (** on class website):
Brook, E.J., S. Harder, J. Severinghaus, E.J. Steig, and C.M. Sucher. 2000. On the origin and timing of rapid changes in
atmospheric methane during the last glacial period. Global Biogeochemical Cycles 14(2):559-572.
Wake, C., K. Yalcin, and N. Gundestrup. 2002. The climate signal recorded in the oxygen isotope, accumulation,
and major ion time-series from the Eclipse Ice Core, Yukon Territory. Annals of Glaciology, Vol. 35, pp. 416-422.
**Wolff, E., and Renato, S., 2007. Methane and nitrous oxide in the ice core record. Phil. Trans. R. Soc. A 365, 17751792.
Yalcin, K. and C.P. Wake. 2001. Anthropogenic signals recorded in an ice core from Eclipse Icefield, Yukon Territory.
Geophysical Research Letters, Vol. 28, pp. 4487-4490.
**Yalcin, K., C.P. Wake and M. Germani. 2003. A 100-year record of North Pacific volcanism in an ice core from
Eclipse Icefield, Yukon Territory, Canada. Journal of Geophysical Research, Vol. 108, 10.1029/2002JD00244.
A note on units:
Note that chemical concentrations in ice cores are sometimes given as microequivalents (meq) per litre and sometimes
and parts per billion (ppb). Microequivalents are used for expressing concentrations of ionic substances and assessing
what types of compounds the various elements may be traveling as. For example, the compound sodium sulfate
(Na2SO4) has one "equivalent" unit of sodium, and two "equivalent" units of sulfate. The conversion between parts per
billion and microequivalents is: ppb * valence charge/molecular weight = microequivalents per liter.
Valence charge is the number of bonds an atom can form. Hydrogen (H) always has valence 1, so other elements'
valences equal the number of hydrogen atoms they combine with. Therefore, oxygen (O) has valence 2, as in water
(H2O); nitrogen (N) has valence 3, as in ammonia (NH3); and chlorine (Cl) has valence 1, as in hydrochloric acid (HCl).
The valence depends on the number of unpaired electrons in the outermost (and, in transition elements, the next) shell of
the atom's structure. The sharing of the unpaired (valence) electrons in a bond mimics the stable configuration of the
noble gases, whose outer shells are full.
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