| This study compares the response of Hudson Bay to a transient warming scenario provided by six coupled atmosphere-ocean general circulation models. The analysis focused on surface temperature, precipitation, sea-ice coverage, and permafrost distribution. The response of the sea-ice cover and permafrost to climate change was found to vary considerably among the models and thus large differences were observed in the projected regional increase in temperature and precipitation. In addition, the climate and hydrology of the Hudson Bay region were analysed for trends in order to provide early evidence of climate change in the region. The Theil-Sen slope approach was used to identify the magnitude of the trends and the Mann-Kendall test assessed their statistical significance. The results showed that warming over Hudson Bay has not occurred in a unidirectional way and, consequently, the trends are sensitive to the time periods chosen for analysis. The warming trends of the last few decades are reflected in the timing of sea-ice formation and break-up, but the strong dependence of ice thickness on snow depth suggests that it is more challenging to identify an early climate change signal using ice thickness data than it is using freeze-up/break-up dates. An asymmetry was observed in the trends of maximum ice thickness, as the ice cover has become thicker over time on the western side of Hudson Bay, while slightly thinning trends and statistically significant trends towards an earlier occurrence of the peak ice thickness were detected on the eastern side. It is inevitable that increasing temperatures in the Hudson Bay region will result in a thinning of the ice cover in the long run, but changes in snow depth will tend to offset the ice thickness trends in the short run. If this trend towards a longer ice-free season continues, as the models suggest, it will have disastrous consequences for the polar bear populations that inhabit the region. |
