Impacts of 1⁰C, 2⁰C, and 4⁰C of Warming on Ship Navigability in Arctic Canada

The Canadian Arctic is a key region for potential trans-Arctic shipping through the Northwest Passage, and has a large number of northern communities culturally and economically connected to the marine environment. Effective governance in a warmer future will require navigational information at an operational scale and which considers indicators and outputs relevant to ship operators and decision makers. In this study, we use a large ensemble of climate model simulations to project changes in sea ice under 1⁰C, 2⁰C, and 4⁰C warming scenarios, and estimate the resulting changes to ship navigability (season length and timing) using current go-no-go regulatory frameworks. Specifically, we convert simulated ice thickness into Risk Index Outcome (RIO) values, allowing the projections to be directly interpretable within the Polar Operational Limit Assessment Risk Index System (POLARIS) used by Arctic shipping companies. We assess changes for multiple ship classes at three levels of spatial granularity: changes across general Canadian Arctic waters, changes to selected regions representative of Canadian supply routes, and community-level changes to seasonality which impacts resupply for Canadian Northern residents.

Results show projected changes to vessel navigability across the Canadian Arctic and adjacent seas are substantive at 2⁰C of warming above preindustrial and profound at 4⁰C of warming. After 2055, all major shipping routes indicate 100% navigation probability for at least part of the summer regardless of vessel type. For some regions, increased navigation of certain ship classes can be expected to pose ecosystem-related concerns. If there is operator tolerance for elevated risk thresholds, it is possible to increase the shipping season length into the fall, suggesting that future conditions may lead to increases in rescue operations. Finally, we present projections for changes in seasonality of sea ice melt for localized Northern Community regions which will impact their health and well-being via changes to hunting and ice travel seasons as well as community resupply during the ice-free season.