By Agence France-Presse The Canadian provinces of Ontario and Saskatchewan said Thursday they would join forces in opposition to the federal carbon tax, in a setback to government efforts to reduce greenhouse gas emissions linked to climate change. (AFP / MANILA BULLETIN) Ontario, the country's richest and most populous province, last month elected climate skeptic Doug Ford, a conservative, as its premier. He had vowed during his campaign to fight the tax, which he contends is damaging to the economy. Saskatchewan, a province as vast as France but with a mere one million inhabitants, filed suit in April asserting that the tax -- a signature issue for Prime Minister Justin Trudeau -- is unconstitutional. "Ontario will join forces with Saskatchewan and use every tool at its disposal to challenge the federal carbon tax," Ford said during a news conference on the sidelines of a meeting of Canada's 10 provincial premiers. "It's a bad tax for families and it's a bad tax for businesses," Ford said, standing next to his Saskatchewan counterpart, Scott Moe. Ford said he was working to rally support from other provincial leaders as well, though it was not immediately clear whether others were joining his cause. The nationwide carbon tax established by the Trudeau government, aimed at inducing companies to curb pollution, is set to rise steadily from Can$10 ($7.50) per ton this year to Can$50 per ton in 2022. Some provinces had carbon taxes in force before this year, but the federal law extends their reach to all 10 provinces. Saskatchewan is second only to Alberta as Canada's top petroleum-producing province, and Environment Canada has identified the oil industry as Canada's biggest contributor to greenhouse gases.