Our low-ball estimate of total yearly CO2 emissions reduction for Canada is 274,000 tonnes. Our optimistic estimate is twice that: 547,000 tonnes. Canada emits about 550M tonnes of CO2 per year. Thus, we are aiming to save 0.1% in carbon emissions.
Below is a detailed calculation:
We are looking to replace 3-to-9km-long commutes with bicycle trips. This is an average distance of 6.5 km per trip, or 65 km weekly. Assuming 3 weeks vacation, that's 49x65 = 3185 km yearly per commuter.
Most Canadian cities have about a 2% bike commute participation rate, except Vancouver, which has 6%. A conservative goal would be to bring the participation rate of all other major cities up to 6% - in the summer months. In the winter months, we assume half the participation (based on bike commute rates from Finland: 20%/10%). So we wish to increase increase average participation by 4%*(7/12)+2%*(5/12) given 5 winter months, that is 3.17%.
We are targeting all 62 Canadian cities above 50,000 population except the Greater Vancouver Area. That is 22,300,000 citizens. [2021 Census]
Out of these, we will take as workers those aged 20 to 64, that is 59% of the population.
Typical Canadian cars emit CO2 at an average rate of 206g/km.
The final yearly CO2 saved is 3185km * 3.17% * 22,300,000 * 59% * 206g/km = 274,000 tonnes.
This is a low-ball estimate. A few important factors that could increase this estimate are:
The benefits of reducing traffic are superlinear because during rush hour cars block and slow down other cars and there is lots of idling. Thus, removing X% of cars from the road during rush hour may reduce emissions by much more than X%, because the other cars have a smoother resulting trip.
This calculation only included daily commutes, but bike lanes can also be used for shopping, community, social, and entertainment trips, all of which help reduce emissions.
Vancouver may also benefit from more bike lanes and increase its bike commute participation rate even more, as it already has a strong biking culture.
The 9km travel range is assumed for average-ability cyclists. However, more performant cyclists may replace much longer trips with cycling. Also, the advent of e-bikes may extend the cycling range for many people.
A well-connected biking network may bring participation higher than 6% in many cities, up to European levels (at least outside winter) of 7% or more, even into the double-digits.