Climate change and sea ice: Shipping in Hudson Bay, Hudson Strait, and Foxe Basin (1980-2016)

The seasonally ice-covered waters of Hudson Bay, James Bay, Foxe Basin, and Hudson Strait ("the study area") are bordered by 39 communities with a total population of roughly 50,000 people, most of whom are Inuit or Cree. Sea ice is a cornerstone of the environment and culture of the study area but is also the main barrier to shipping traffic, which has been growing in the area. This paper presents a review of sea ice and shipping in the study area and an analysis of shipping accessibility as represented by the timing of breakup, freeze-up, and the open water season in its offshore and local waters. Offshore ice timing was analyzed using passive microwave-based data for 1980-2014; local ice timing near Rankin Inlet, Churchill, Kuujjuarapik/Whapmagoostui, and Salluit was examined using Canadian Ice Service ice charts for 1996-2016. Open water was defined using sea ice concentration thresholds of <= 15% (offshore) or <20% (local) in an attempt to represent accessible conditions for open water shipping vessels. The results for both offshore and local waters display considerable spatial variability. For offshore waters, breakup currently occurs between 17 May and 19 August and freeze-up occurs between 22 October and 30 December, with overall trends (1980-2014) of +0.58 days year(-1) towards an earlier breakup, +0.47 days year(-1) towards a later freeze-up, and +0.97 days year(-1) towards a longer open water season. Also, significant relationships amongst breakup and freeze-up were observed. For local waters, the 1996-2016 average open water season at the four communities varied between 112.7 days (Churchill) and 154.7 days (Kuujjuarapik/Whapmagoostui). Ultimately, shipping accessibility to Rankin Inlet, Churchill, and Salluit appears to be limited by their local ice timing, while accessibility to Kuujjuarapik/Whapma goostui appears to be limited by ice timing in northeastern Hudson Bay.