Ice core project

From Bart:

Dr. Grumbine,

I have a question which is off-topic, but I was hoping for a suggestion. I'm doing an undergraduate statistics project, and I want to make mine climate change-oriented. I was hoping for some useful suggestions as to what would make a good idea-- I'm hoping of doing some kind of ice core data analysis (of some variable). My background in statistics is confined to a beginner class, but I do have math background out to differential equations and calc courses, so I can pick up.

I ask because stats in climate can get ugly pretty quick...principal component analysis and all that stuff is a bit beyond me. I still want something that is practical and informative. I can do the research in the climate literature and understand the terminogy; my barrier is moreso in data analysis background.

I'll throw this open also for ideas from readers. First step, I think, in a science project is to get a lot of ideas together.

Some good books to read for the statistics side of things are:
How to Lie With Statistics by Darrell Huff
Lady Luck by Warren Weaver
The Visual Display of Information by Edward Tufte

On the ice core side:
The Two Mile Time Machine by Richard Alley
Ice Ages: Solving the Mystery by John and Katherine Palmer Imbrie

Most relevant to your specific thoughts is Alley's book. But read the others when you have time.

For projects ...
Well, one part would be to start looking at the ice core literature and see what suggests itself. Starting with the Vostok ice cores from the mid-1980s there has been a lot of publication on these in Science and Nature (easy journals to get hold of). For doing this, it's good to think a bit about what kinds of analysis techniques you have from your stats class, and then see what has been published on that sort of analysis. While it's likely (but not guaranteed!) that the analysis has been done before, just not published, it's also possible that it hasn't been done.

I'd stay away from the more hard core time series analysis side of things here as this is your first stats class and the ice core time series are not on the more straightforward side of that problem.

But it should be doable to have a look at the ice cores for the 'climate' lengths of time in the way I was describing, casually, in how to decide climate trends and finding climate means. The ice cores have coarser resolution, but this is made up by the greater time spans they cover. An important part of the decision that I described in the means note is that if you go longer (than 30 years, in that case) new processes might start acting. In that case, you want some even longer averaging period -- long enough to average out those processes that are, say, 50-200 years long, and short enough to not be much affected by the ones 1500-2500 years long. But what is that period? Is it the same for all variables (CO2, Salt, dust, ...)? Is it the same for glacials and interglacials?

The hard core part of the project is to go beyond what I did, which was only eyeball verification. To do that, you want to find appropriate statistical tests to determine that, for instance, the mean as computed with a 300 year span of data is essentially the same (and what would 'essentially the same' mean in statistics?) as for 400 years, but both are meaningfully different from the means computed for 200 or 600 years.

Similarly, how can you tell that the means for glacial period are different than means for interglacials? Better, how can you determine objectively from the data just when the glacials and interglacials start and end?

Ice core data is archived at the National Geophysical Data Center. You'll also have to do some thinking about which data to use, how. The longest time series come from Antarctica, but they also have the worst time resolution. Better resolution comes from Greenland, but it's shorter. Better time resolution still comes from Andean and Himalayan glaciers, but they're much shorter.

The question of what are the climate periods in ice cores is an open one in the professional literature. At least as of fall 2007 when an ice core person was asking me how sea ice people selected their climate period, and I asked her about ice core people did.

Good luck on whatever version of project you do. And do let us know how it turns out!