The campaign is part of the movement's tradition of asking members to vote on what socially responsible campaign it should fund. It is spending £500,000 in conjunction with the World Wildlife Fund (WWF) to oppose oil drilling projects in the tar sands.
The first stage of the campaign is a CFS-funded legal challenge by the indigenous tribe Beaver Lake Cree Nation in the oil-rich Canadian province of Alberta, where the tar sands have encroached on the tribe's hunting grounds. CFS has donated £50,000 to the group.
CFS claimed the tar sands projects of Shell, BP, ExxonMobil, ConocoPhillips and Total could all be affected if the Beaver Lake Cree's legal action is successful.
CFS and WWF aim to raise awareness of the trend for oil companies to extract oil from unconventional sources, damaging the environment in the process.
WWF-UK campaign director Dave Norman said: "Tar sands are already Canada's largest single greenhouse gas emitter and mean that Canada will not meet its international obligations on climate change."