Agence France-Presse: Canada must introduce a carbon tax, or a cap and trade system for greenhouse gas emissions, or both, if there is any hope of the country deeply cutting its CO2 emissions by mid-century, a report commissioned by the government said Monday. And Canada must act now or face higher costs in the future for reducing CO2 output linked to global warming, said the report by the independent National Round Table on the Environment and the Economy (NRTEE). "These findings and …