The Canadian dollar weakened against the greenback on Tuesday, and the yield on benchmark government debt climbed. The loonie was trading 0% lower at C$1.3637 to the greenback, or 73.33 U.S. cents, after trading in a range of 1.3629 to 1.3647. Canadian government 10-year bond yields rose 1 basis points to 3.485%. The yield on similar U.S. government benchmark debt rose to 4.2959%. U.S. August crude futures fell 37 cents to $81.96 a barrel on Tuesday.