Warming will significantly affect winter road construction, maintenance, and use. Warming trends and associated decreases in the length of winter road seasons will therefore continue to have significant impacts on communities as winter roads are the most economical method for the transport of supplies.
As the warming climate is already having an impact on winter road construction, how long will winter roads be a viable way of accessing the communities they serve?
The challenge in answering that question is to identify the climate change variables and thresholds that are appropriate indicators of the length of operation of these roads. The opening of winter roads depends largely on sufficient ice development before construction, while the timing and operational length of these roads are affected by a variety of other climate factors including air temperature, precipitation, snow, and wind.
Research was conducted to analyze trends in the seasonal timing of opening dates of the James Bay Winter Road as correlated with air temperature.1,2 The analysis found that a minimum of 380 Freezing Degree Days (FDDs) below 0°C (see Box 1) during the period of road preconditioning was a critical factor in a favourable construction period (historically, the preconditioning period is from October 1st to December 31st). However, the preconditioning period may shift into January as the climate warms, and the spring melt period will also start earlier than in the past. The focus of the analysis below is on the shifts in the timing of achieving this 380 FDD threshold during the preconditioning period.
Knowing this threshold value, it is possible to explore scenarios that examine the viability and longevity of winter roads over the coming century. FDD accumulations starting after September 30th (the traditional start of the preconditioning period) were examined for several communities served by winter road corridors (Big Trout Lake, Lansdowne House, Moosonee, Red Lake, and Kapuskasing) to assess trends in historical and projected FDD accumulations. The results of this analysis reveal that the date at which ice road construction can begin will shift through the century.