This index from the Dallas Fed, developed by Lutz Kilian, measures global real economic activity in industrial commodity markets. This business-cycle index is expressed in percent deviations from trend. It is derived from a panel of dollar-denominated global bulk dry cargo shipping rates and may be viewed as a proxy for the volume of shipping in global industrial commodity markets.
For further discussion of the advantages of this index compared with measures of global real GDP or global industrial production, see Kilian and Zhou (2018).