Canadian Press: Canada could be barred from an international carbon-trading system if a United Nations investigation finds it broke Kyoto Protocol rules for greenhouse-gas reporting. The UN Climate Change Secretariat says Canada was notified on May 5 that it would be investigated for allegedly violating a Kyoto reporting requirement. Canada and other Kyoto signatories are obliged to keep a national registry of greenhouse gases. The registry tracks holdings of greenhouse-gas credits and shows …