I was wondering if anyone could help me? - multi proxy records

1. Compare the number of proxy datasets used in each.  For example, the Mann et al. "hockey stick" reconstruction used over 1200 proxies, whereas Craig Loehle's used 18.
2. Look at the temporal coverage of the proxies used.  Again using Loehle as an example, many of the proxies he used ended in the early to mid 20th century, and thus don't incorporate the recent warming trend.
3. See which and how many of the proxies use tree ring data.  The accuracy of tree ring proxies is something of a bone of contention.  Loehle's 18 proxies didn't use any tree ring data.  However, the Mann reconstruction shows essentially the same results with or without tree ring data.

RealClimate on Loehle

RealClimate on Mann

Oh, environmental change and not global temperatures.  I should have read that more carefully.  So you're talking about how human effects have impacted the local environment of these areas?

So are you supposed to evaluate the paper itself or what it means for the local environment in Sweden?  Not having access to the papers makes it tough to help, but gcnp probably has access.

Quote:

Originally Posted by snixx 

i think i am supposed to evaluate the papers themselves, and critique the key indicators though i am slightly unsure because the only thing i have been given is the question given above.

The two papers come to different reconstructions of past climate (I think anyway, I didn't read them closely).  My hunch is that the assignment is for you to figure out where the two studies agree in their conclusions, and where they differ, and then critique each paper and draw some conclusions as to why they differ.  Probably the intent is to get you to think of how the different proxies might lead one to get different climate reconstructions.  For example, one uses only pollen and diatoms and the other uses pollen, diatoms, *and* a carbon isotope record from a sediment core (I think, again, I scanned them very quickly).  Although my interpretation for what to do seems a little advanced for an undergraduate exercise.  Are you in fact in graduate school?  For what it's worth, if you follow through with what I've outlined and did a good job, if I were your prof you would get an awesome grade on the assignment.  But I'm not your prof. 

Anyway, I forwarded the papers to Dana.  He can give you his assessment.  Hopefully he won't read what I've written above so I don't bias him.