Climate Warming and Polar Bears in the Arctic

„Possible Effects of Climate Warming on Selected Populations of Polar Bears (Ursus maritimus) in

the Canadian Arctic“

Ian Stirling and Claire L. ParkinsonArctic, Vol 59, NO. 3 (September 2006), P.261-275

http://animals.nationalgeographic.com/staticfiles/NGS/Shared/StaticFiles/animals/images/primary/polar-bear-wet.jpg

Hypothesis

„In this paper, we evaluate patterns of sea-ice breakup (...) to test the hypothesis that sightings of more polar bears in these populations are due in part to changes in sea ice, possibly resulting from climate warming, and do not necessarily indicate population increases.“

Study Area: Eastern Canadian Arctic

Picture from the discussed paper, p. 263

http://www.map-of-canada.org/canada-map.gif

Study Area: Eastern Canadic Arctic

The five areas are ice-free in summer

They are chosen according to polar bear subpopulations

Methods: Measurement of Sea Ice

-Satellite data from 1972 to 2004

-Measurement of microwave radiance: → Easily pass through most clouds→Ice and water differ

-Used in this study: → Date on wich the total cover of sea ice declined to 50% →Ecologically significant (other study)

Results and Discussion

Western Hudson Bay – Results

p=0.003

Western Hudson Bay – Discussion

Davis Strait – Results

p=0.35

Davis Strait – Discussion

Evaluation: Strengths

Long observation period (over 30 years)

Reliable data source (satellites)

Large study area

Investigation of areas that are ecologically meaningful for the polar bear

Evaluation: Weakness 1

No division of results and discussion

This leads to Piramyding: They interlace own results, results from other studies and the discussion of both

Mixture of meta study and original study

Evaluation: Weakness 2

EHB: Their own data is not significant→They do not discuss why, mention other studies that support their thesisand conclude from the other studies (P. 271)

Much additional information that does not directely deal with the main thesis

Citation of unpublished results or observations from himself (9 times)

Own Opinion in short

Good data and interpretation

The main points could have been summarized within 4 pages