We had missed this one, but one of our readers helped us to find that Air Canada is also offering the purchase of carbon offsets at their website. The website even includes a calculator that helps determining the CO2 their trip will generate, the cost to offset it and a way to pay the cost of offsetting this trip, together with their ticket purchase or at another time.
For example, based on the specifications of Air Canada's current aircraft, it will cost 19.20 CAD for a customer to offset their share of carbon emissions on a return flight from Toronto to London and 12.80 CAD for a return flight from Vancouver to Montreal.
Air Canada's partner in this program is Zerofootprint. According to a statement by Deborah Kaplan, Executive Director of Zerofootprint, "Carbon offsetting balances out climate-changing carbon dioxide that is put into the atmosphere by our activities, it highlights the environmental cost of goods and services we buy, and, when you offset with trees, it restores ecosystems, habitats, watersheds, greens communities and creates jobs."
[Source: Air Canada thanks to J. Riley]