Indeed, macroeconomic uncertainty directly affects both consumption and trade of biofuels because there is substitution between ethanol and biodiesel, the level of the substitution depends on the relative prices. Furthermore, mandates serve as a direct link between crude oil and biofuel consumption, such that uncertainties surrounding the world crude oil price are directly transmitted to the biofuels markets, and to the sugar markets. Additionally, the uncertainty coming from GDP growth affects demand for fossil fuels on which the mandates are based.