How Soon is now?

The paper itself (both versions) is a collection of standard arguments for why everything is uncertain and nothing can be concluded, but did actually include a little analysis. Specifically, the claim was made that temperatures in Churchill, Manitoba (close to the center of the Western Hudson Bay population of bears) had not risen, and that instead, any multidecadal variations in temperatures affecting the bears were related to the Arctic Oscillation (AO), a mode of natural variability. Of course, temperatures in the Churchill region have risen, and the ice extent in Hudson Bay is melting earlier and forming later (by about a month in each case) than 30 years ago. But the interesting aspect is the impact of the AO which certainly affects short term temperatures in the Arctic.

Regressions of winter temperature anomalies with the strength of the AO (JISAO). (ÂșC change in temperature per unit increase in the AO – for reference, the AO varies from roughly -3 to 3 on a monthly timescale).

Andrew Derocher, who signed his review, queried why the figure showing an impact of the AO on temperature (r2=0.52) used the data from Frobisher Bay (Iqaluit) in the Labrador Sea instead of the data from Churchill. Frobisher Bay is just under 1000 miles away from Churchill and doesn’t border Hudson Bay at all, so its relevance to bears in Western Hudson Bay is somewhat mysterious. It is however very close to the center of the AO influence (as seen in the above figure). Derocher suggested that Dyck et al use the correlations at Churchill instead (makes sense, no?). In the finally published paper (in 2007) however, the correlation with the AO was still using the Frobisher Bay data – exactly as it appears in the first draft in 2003.

What the files reveal however, is that Soon had already calculated the correlations of Churchill temperatures to the AO, and found that the correlation was very low – regardless of what month or season he used (the files are dated to January 2003 – prior to Derocher’s review). None of the correlations showed an r2 > 0.24 (highest in August), and most were much smaller (especially during the key spring period where the variance explained was less than 5%). Note that a value like r2=0.24 is not necessarily meaningless — indeed, for the number of data points involved here (between 50 and 60), this is probably statistically significant relative to a standard ‘red noise’ null hypothesis. However, the variance explained is small.

Soon had also calculated the impact of the AO on the Frobisher Bay data and, unsurprisingly, used the seasonal correlation that had the highest correlation. The fact that Frobisher Bay temperatures and Churchill temperatures are only loosely correlated (also calculated by Soon) (highest monthly r2 was 0.22) was not mentioned in either version of the paper.

The link is made (in the 2003 version) using:

… the temperature and climatic conditions around the Hudson Strait and Hudson Bay areas have close association with the AO circulation index

which is an attempt to imply that the Hudson Strait connection, also applies to Hudson Bay (which Soon already knew was untrue). The version in the 2007 paper was only slightly different:

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